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Article

New Approach to the Systematics of the Section Psammiris (Iris, Iridaceae): What Does Chloroplast DNA Sequence Tell Us?

by
Eugeny V. Boltenkov
1,* and
Elena V. Artyukova
2
1
Botanical Garden-Institute, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690024, Russia
2
Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690022, Russia
*
Author to whom correspondence should be addressed.
Plants 2023, 12(6), 1254; https://doi.org/10.3390/plants12061254
Submission received: 29 December 2022 / Revised: 22 February 2023 / Accepted: 3 March 2023 / Published: 9 March 2023
(This article belongs to the Section Plant Systematics, Taxonomy, Nomenclature and Classification)
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Abstract

:
Iris sect. Psammiris comprises rhizomatous perennials distributed in the north temperate zone of Eurasia. The systematics of the section are currently based on morphology, and the phylogenetic relationships within it still remain unclear. In the framework of Iris systematics, we conducted molecular and morphological analyses of the currently recognized I. sect. Psammiris species to elucidate the taxonomic composition and relationships within the section. The phylogenetic reconstructions based on sequence variation of four noncoding chloroplast DNA regions support the monophyly of I. sect. Psammiris, which includes I. tigridia, while I. potaninii var. ionantha belongs to I. sect. Pseudoregelia. The proposed novel classification of I. sect. Psammiris recognizes three series: an autonymic series with I. humilis, I. bloudowii, and I. vorobievii and two unispecific series (I. ser. Potaninia with I. potaninii and I. ser. Tigridiae with I. tigridia). In addition, the taxonomic statuses of I. arenaria, I. ivanovae, I. kamelinii, I. mandshurica, I. pineticola, I. psammocola, and I. schmakovii are clarified herein. We provide a revised taxonomic treatment for I. sect. Psammiris, including notes on the types; updated information on species synonymy, distributions, habitats, and chromosome numbers; and a new identification key to the species. Three lectotypes are designated here.

1. Introduction

Psammirises, or sand irises, are a small group of Iris L. (Iridaceae) that comprises rhizomatous perennials distributed exclusively in the north temperate zone of Eurasia and found in sandy soils of steppes, open meadows, and hillsides. As the most cold-resistant among I. subgen. Iris (bearded irises), psammirises have always attracted attention as garden plants [1]. In fact, almost all psammirises are successfully blooming and fruiting in culture in Yakutsk (at approximately latitude 62° N), Russia [2].
This group was established by Spach [3] as I. subgen. Psammiris Spach for plants with helically twisted withering flowers and arillate seeds; however, Baker [4] transferred it to I. sect. Pogoniris (Spach) Baker, which was supported in references [5,6,7]. Lawrence [8] placed some of psammirises in I. ser. Pumilae G.H.M.Lawr. and others in I. subsect. Hexapogon (Bunge) Benth. Taylor [9] eventually re-established psammirises at the section level, which was subsequently supported by the authors of [1,10,11,12,13,14,15,16]. Four species were included in I. sect. Psammiris (Spach) J.J.Taylor [9]: I. humilis Georgi, I. bloudowii Ledeb., I. mandshurica Maxim., and I. potaninii Maxim. (Figure 1). Currently, the section comprises eight species including the recently described I. vorobievii N.S.Pavlova, I. psammocola Y.T.Zhao, I. kamelinii Alexeeva, and I. schmakovii Alexeeva [15,17]. Despite this recent advancement in the knowledge of the section, there are still numerous uncertainties regarding its taxonomic composition and systematics.
One of the best-known species in the group, I. humilis (Figure 1a–c), was initially described by Johann Gottlieb Georgi in an area of the Lake Baikal coast between the Angara River and Olkhon Island [18]. Then, for about two centuries, it was referred to by various researchers, including Georgi [19], as I. flavissima Pall. [5,6,7,20,21,22,23,24,25,26,27], which had been described on the basis of plants from Transbaikalia [28]. Bobrov [29] noted that I. humilis and I. flavissima were actually the same species and that the name I. humilis had priority, as was later supported (e.g., [9,30]). However, the taxonomic concept within I. humilis has varied widely.
Another species, I. mandshurica, was described based on plants collected near the Razdolnaya River (Primorsky Krai, Russia). It was often considered an ally of I. flavissima or as an intermediate between I. flavissima and I. bloudowii [5,24,26,31]. In the Iris treatments of the Russian Far East flora, I. mandshurica was indicated as a synonym of I. humilis [32,33]. Nevertheless, a preliminary molecular analysis shows that I. mandshurica merits to be recognized as a separate species [34].
After being described, I. arenaria Waldst. et Kit. was considered a Hungarian representative of I. humilis (=I. flavissima) [10,13,24,26,35] or, less commonly, as a separate species [5,36,37,38]. Ugrinsky concluded that I. flavissima and I. arenaria are forms of a single species that differ mainly in geographical terms: I. flavissima subsp. stolonifera f. occidentalis Ugr. (=I. arenaria) is a western representative from Eastern Europe, and I. flavissima subsp. stolonifera f. orientalis Ugr. is an eastern representative from Ukraine and western Russia [22,23]. Klokov recognized the latter form at the species level under the name I. pineticola Klokov [39], which is currently included in the species aggregate with I. humilis [1,10,12,13,26,40] or is considered as endemic to Ukraine [41]. In addition, I. schmakovii, originally described as I. humilis var. umbrosa Alexeeva from Mongolia [17], is currently treated as a synonym of I. humilis [42].
Iris bloudowii (Figure 1d) was described by Carl Friedrich von Ledebour [43] from plants gathered by him in the Gromotukha River valley on the southern forested slope of the Ivanovsky Ridge (Kazakhstan Altai) and originally identified as I. flavissima [44] (p. 91). It is closely related to I. humilis and was therefore treated as a larger variety of I. flavissima [5,21,26] or a synonym of I. humilis [45]. Iris bloudowii was also regarded as a separate species [5,20,23,24], which is supported to date [15,27,46,47,48].
While revising the Far Eastern Iridaceae, Nonna Pavlova [32] came to the conclusion that the plants from southern Khasansky District (Primorsky Krai, Russia) collected near the borders with China and North Korea were a separate species, I. vorobievii (Figure 1e). It is a little-known species that was referred to as I. mandshurica by Georgi Rodionenko [1,12]. He believed that I. vorobievii is unrelated to I. humilis and should be transferred to I. sect. Pseudoregelia Dykes, which has not been confirmed by a preliminary molecular study [34].
The well-known psammiris, I. potaninii (Figure 1f–h), was described by Carl Johann Maximowicz from Russia (Altai and Transbaikalia) and Mongolia [20]. Rodionenko suggested I. potaninii to be transferred to I. sect. Pseudoregelia, since it is the closest relative to I. tigridia Bunge [1]. Moreover, phylogenetic studies showed that I. potaninii is not monophyletic, as an autonymic variety belongs to I. sect. Psammiris, whereas I. potaninii var. ionantha Y.T.Zhao described from Qinghai Province, China [49], is in I. sect. Pseudoregelia [14,50,51]. It was stated that I. potaninii var. ionantha is actually the same taxon as I. thoroldii Baker [52], which was previously recognized as a distinct species [27,47]. Despite this statement, I. potaninii var. ionantha has been recognized at the species level as I. zhaoana M.B.Crespo, Alexeeva et Y.E.Xiao and included in I. sect. Pseudoregelia ser. Tigridiae Doronkin [16].
Iris psammocola, a little-known species, was described by Yu-Tang Zhao on the basis of a single specimen collected in the vicinity of Baijiatan, Ningxia Hui Autonomous Region, China [53]. It has been accepted in the botany databases [42,54]. In 2005, I. psammocola was reported, along with I. potaninii, from the Tsugeer-Els area, a sand cluster of the Ubsunorskaya Kotlovina Biosphere Reserve, southeastern Republic of Tuva, Russia [55]. In addition, I. potaninii var. arenaria Doronkin, described from Kyakhtinsky District, southern Republic of Buryatia, Russia [11], was synonymized with I. psammocola [55]. Subsequently, I. psammocola was reported from the Altan-Els sand dune region of the Borig-Del-Els sandy areas, the Mongolian part of the Uvs Lake Basin [56]. It was asserted that I. psammocola occurs only on sandy arrays and has a disjunctive distribution range in Central Asia [55,56]. It is a relative of I. potaninii and has a chromosome number of 2n = 22 [55]. The same chromosome number has been reported for I. potaninii from eleven localities in the Altai Republic [57,58], from the Republic of Buryatia [57,59], from the Republic of Tuva, and the Zabaykalsky Krai [60]. In our opinion, the Russian populations of I. psammocola remain in question and require further studies, since their identity to I. potaninii is probable.
Iris kamelinii, another relative of I. potaninii, was described by Nina Alexeeva on the basis of plants collected near Verkhniye Boguty Lake on the western side of the Chikhachev Ridge, Southeast Altai Mountains, Russia [61]. According to the author, I. kamelinii in the type locality occurs together with I. potaninii [15,62] and has the same chromosome number, 2n = 22 [58,61]. Moreover, I. kamelinii shows the nearest affinity with I. potaninii in flowering [63] (p. 51) and in seed morphology [64]. Meanwhile, I. kamelinii, treated as endemic to the Altai Mountain Country, also grows in Mongolia and China [17,65].
Phylogenetic analyses of the Iris species based on cpDNA sequence data have shown that I. sect. Psammiris and I. sect. Pseudoregelia are not monophyletic [14,50,51,66]. As most authors suggested, I. tigridia (Figure 1i–m) has been included in I. sect. Pseudoregelia [1,10,11,12,30,67,68]. Accordingly, the combination I. sect. Pseudoregelia ser. Tigridiae has been proposed for I. tigridia and its relative, I. ivanovae Doronkin [11]. However, some authors consider I. tigridia and I. potaninii (from I. sect. Psammiris) to be closely related [1,27]. In a phylogenetic study of Siberian irises, I. tigridia and I. ivanovae formed a sister group with psammirises [69]. Other molecular studies also supported the inclusion of I. tigridia in I. sect. Psammiris [14,50,51,66]. Subsequently, however, the specimen cited as “… R01-18” in references [50,66] was interpreted as a misidentification with I. tigridia and referred to as I. kamelinii [15]. Nevertheless, a recent study confirmed that I. sect. Psammiris is a monophyletic taxon when I. tigridia is included [14]. Despite the considerations mentioned above, it was stated that I. tigridia and I. ivanovae, both with single-flowered stems, belong to I. sect. Caespitosae Alexeeva [15,17,70]. However, I. pandurata Maxim., the type species of I. sect. Caespitosae [71], is attributed to I. sect. Pseudoregelia [68,72]. It is a distinct species characterized by a two-flowered stem and is narrowly endemic to China, distributed in Gansu and Qinghai provinces [27,47,68].
Iris ivanovae, described from Kharanor, Zabaykalsky Krai, Russia, is considered to be a Transbaikalian, Mongolian, and Chinese representative of I. tigridia [73]. All experts on the Mongolian flora listed I. tigridia for the Khuvsgul, Khentei, Khangai, Mongolian Dahuria, and Middle Khalkha phytogeographical regions [27,74,75,76,77]. Moreover, Gubanov regarded I. ivanovae as a synonym of I. tigridia [76]. On the contrary, it was stated that all the plants from Mongolia previously named I. tigridia [25,27,76] belong to I. ivanovae [17,70,78]. Additionally, I. ivanovae is not accepted by the authors of the Flora of China since they did not see any specimens [46].
In view of all the above facts, a molecular study would be a great contribution to understanding the taxonomic composition and phylogenetic relationships among the I. sect. Psammiris species. A few studies based on cpDNA data have examined the relationships between different taxa within Iris, including psammirises [14,50,51,66,67,69,72], and elucidated the I. sect. Psammiris systematics, although only to a limited extent. A combination of trnH-psbA and trnL-trnF was previously proposed as the core barcode for plants [79]. As in our previous publications, in the present study, we focused on nucleotide sequences of four cpDNA noncoding regions (trnH-psbA, rps4-trnSGGA, trnS-trnG, and trnL-trnF) that proved to be useful as phylogenetic markers [34] and that we widely applied to assess interspecific relationships in I. subgen. Limniris (Tausch) Spach [80,81,82]. In the framework of the taxonomic research carried out on Iris, the objectives of the present study are as follows: (1) clarify the phylogenetic relationships of I. sect. Psammiris and I. potaninii var. ionantha with I. tigridia using four cpDNA regions; (2) elucidate the phylogenetic relationships within I. sect. Psammiris and determine the taxonomic statuses of I. arenaria, I. ivanovae, I. kamelinii, I. mandshurica, I. pineticola, I. psammocola, and I. schmakovii; (3) study the morphological characters of the I. sect. Psammiris species; and (4) compare the results of molecular and morphological studies in order to resolve the systematics of I. sect. Psammiris.

2. Materials and Methods

2.1. Taxa Used

We attempted to provide an extensive taxon sampling as possible and ensure that all accessions were fully verified. One of us (E.V. Boltenkov) undertook two botanical expeditions to southern Siberia (Russia): to the Altay Republic in 2020 and to Transbaikalia (Republic of Buryatia and Zabaykalsky Krai) in 2021. In addition, we collected plant material in Primorsky Krai, Russia, in 2020–2021. The complete list of the examined taxa, including information on samples, is provided in Table 1. The collected samples approximately represent the distribution range of the I. sect. Psammiris species (Figure 2).
The taxon samples for the present study are as follows: I. psammocola from the Republic of Tuva, Russia, including the sample TTL specified in reference [55] (four accessions); I. potaninii from the Altai Republic, Republic of Buryatia, as well as Zabaykalsky Krai, Russia, and Mongolia (25 accessions); I. kamelinii from the type locality (ABL) and two of the three Mongolian specimens specified in reference [17] (three accessions); I. bloudowii from Kyrgyzstan, Kazakhstan, and the Altai Republic, Russia, including AUY, a sample closest to the type locality (10 accessions); I. pineticola from a pine forest in Ukraine west of the type locality (two accessions); I. humilis from Belgorod Oblast, Altai Krai, as well as the republics of Altai, Tuva, and Buryatia, Zabaykalsky Krai, and Amur Oblast, Russia, including four samples from the type locality of I. flavissima (17 accessions); Hungarian samples of I. arenaria from the location where the species was described (three accessions); I. schmakovii from the type locality (two accessions); I. mandshurica from Primorsky Krai, Russia, including two samples (GSS and SRS) from the type locality (four accessions); I. vorobievii from Primorsky Krai, Russia, including a sample (KKR) from the type locality (two accessions); I. tigridia from the Altai Republic, including a sample (ACR) from the type locality (four accessions); I. ivanovae from the Republic of Buryatia and Zabaykalsky Krai, including a sample (ZKV) from the type locality (seven accessions); I. goniocarpa Baker from Sichuan and Gansu provinces, China (two accessions); and I. potaninii var. ionantha from Qinghai Province, China (one accession). The sampling localities for each species under study (except the I. sect. Pseudoregelia species) are shown in Figure 2. Two samples (CQM and CSJ) for which accurate species identification by morphological features was impossible were labeled as unidentified Iris samples.
During the fieldwork in the type localities, I. kamelinii was collected on 6 June 2020 from the northern slope opposite the northern bank of Verkhniye Boguty Lake, where it was found in flowering on soddy soils of mountainous steppes [84] on the hill and in fruiting opposite the hill at the base of the mountain slope (Figure 3a,b). Iris ivanovae was collected on 5 June 2021 at the end of flowering from a chestnut soil in a dry steppe heated at noon, where it was found growing, along with Stipa krylovii Roshev., on a sunlit lower part of the northern slope (Figure 3c,d). The type locality of I. potaninii var. arenaria was inspected twice; however, these plants were not found (although I. tigridia was abundant there), and the taxon is therefore not included in the analysis. No samples of I. psammocola were available from the type locality.

2.2. Plant Samples, DNA Extraction, and Sequencing

For genetic analysis, leaf samples were collected across the distribution range of the I. sect. Psammiris species. Total genomic DNA was isolated from the leaf samples collected during the fieldwork and dried in silica gel or taken from the herbarium specimens deposited at ALTB, E, KW, LE, MHA, MW, NENU, and UUH (herbarium codes according to Index Herbariorum [83]). The methods for DNA extraction, amplification, and direct sequencing of four cpDNA noncoding regions (trnH-psbA, rps4-trnSGGA, trnS-trnG, and trnL-trnF) were described previously [34,85]. The cycle sequencing reactions were performed on both strands, and fragments were separated on an ABI 3130 genetic analyzer (Applied Biosystems, Bedford, MA, USA) at the Joint Center of Biotechnology and Gene Engineering, the Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch, Russian Academy of Sciences (Vladivostok, Russia). Forward and reverse sequences for each region were assembled using the Staden Package, version 1.4 [86]. In a preliminary study, no polymorphism in the cpDNA regions was found in the sample of five individuals from the localities of I. arenaria, I. humilis, I. kamelinii, and I. potaninii; therefore, one specimen from each locality was used for further analysis. The sequences of the four cpDNA regions obtained for 88 accessions representing 14 taxa were deposited in the GenBank database. The accession numbers for all the sequences used are listed in Table 1.

2.3. Sequence Alignment and Phylogenetic Analysis

The sequences of each cpDNA region were aligned manually in SeaView version 4 [87] using the CLUSTAL algorithm, manually edited when necessary, and concatenated for each specimen. We included indels and length variation in mononucleotide repeats in the dataset because the repeatability tests allowed for exclusion of PCR errors. In the dataset, we also included the sequences for the most frequent haplotypes identified previously [34] in the localities of I. humilis (ALT-03), I. mandshurica (NAKH-01 and NAKH-07), and I. vorobievii (KRAS-01, KRAS-03, and KRAS-04). The haplotypes were identified on the basis of combined DNA sequences using DnaSP version 5 [88]. A network of haplotypes was constructed using Network version 4.6 [89], with each deletion/insertion treated as a single mutational event, regardless of size, and using the MJ method with default settings.
Phylogenetic relationships among the I. ser. Psammiris species were assessed using the MP and ML methods as implemented in PAUP version 4.0 b10 [90], as well as the BI method in MrBayes version 3.2.2 [91] via the CIPRES portal [92]. The dataset for the phylogenetic analysis included haplotypes obtained previously [80,81,82] for I. dichotoma of I. subgen. Pardanthopsis (Hance) Baker and for 14 species representing four series of I. subgen. Limniris as outgroups. For the MP method, optimal trees were found using a heuristic search with 1000 random addition sequence replicates, starting trees obtained via stepwise addition, TBR branch swapping, and the MulTrees option in effect. For the ML and BI methods, the GTR + I + G model was selected according to the Akaike information criterion using Modeltest version 3.6 [93]. ML heuristic searches were performed using the resulting model settings, 100 replicates of random sequence addition, TBR branch swapping, and the MULTrees option. In BI, using the default prior settings, two parallel MCMC runs were carried out for 10 million generations, with sampling every 1000 generations for a total of 10,000 samples. Convergence of the two chains was assessed, and PP was calculated from the trees sampled during the stationary phase. The robustness of nodes in the ML and MP trees was tested using bootstrap with 1000 replicates.
Degrees of divergence between the species were calculated based on nucleotide substitutions using DnaSP. Pairwise FST among them were determined by AMOVA as implemented in Arlequin version 3.5 [94]. Significance of genetic distances was tested using 1000 random permutations.

2.4. Morphological Data

To compile a morphological key to the accepted species of I. ser. Psammiris in the present study, 22 characters were selected for comparison: (1) rhizome shape (creeping, forming branches like stolons or shortened or nodose, slowly creeping (compact)), (2) rhizome diameter, (3) root shape (adventitious roots gradually tapering to the apex, not thickening (equal); fleshy at the proximal part, resembling a cone (obconical); or evenly thickened at the proximal part with wrinkled transverse patterns (contractile)), (4) root diameter (measured at the proximal end), (5) leaf shape (straight, sword-shaped rosette leaves with more or less parallel margins (ensiform) or one slightly convex margin falcate at the distal part and margins abruptly apically narrowed (subfalcate)), (6) leaf apex (rosette leaves apex straight or slightly incurved, gradually narrowed (narrowly acute), or abruptly narrowed (acute)), (7) leaf texture (rosette leaves noticeably tough or less tough and flexible (thin); the surfaces finely ribbed (smooth); or with discrete central veins (ribbed)), (8) leaf length (measured from the base to the apex of the longest rosette leaf), (9) leaf width (measured at the broadest part of the widest rosette leaf), (10) stem height (measured from the base of the flowering stem to the base of the outer bract), (11) stem branching (classified as simple, bearing only the terminal cluster (designated as 0), or branched, with 1–2 lateral one-flowered cluster(s)), (12) number of flowers (flowers per stem), (13) cauline leaf length (measured from the base to the apex of the upper cauline leaf), (14) number of bracteoles (secondary bracts, i.e., bracteoles, per terminal cluster of the inflorescence), (15) bract length (measured from the base to the apex of the outer bract of the terminal cluster), (16) bract texture (coriaceus, pliable but thin when dry bracts (tough) or membranous and somewhat translucent (thin)), (17) pedicel length (measured from the base of the terminal cluster to the ovary base of the first blooming flower), (18) tube length (measured from the ovary apex to the base of the outer perianth segments, i.e., falls), (19) flower color (the flower color based on personal observations), (20) fruit length and (21) width (obtained for the first fruit of the terminal cluster), and (22) fruit shape.
The scores of the characters for each species were obtained from living specimens collected from wild localities; from our own observations of herbarium specimens at AA, ALTB, BM, E, IRK, K, LE, MHA, MW, NENU, NS, NSK, TK, UUH, VBGI, and VLA, including the original material for the names studied; and from the relevant species descriptions available in the literature [32,45,95,96,97]. The rhizome and root diameter were measured in the dry state with a digital Vernier caliper Series 532 (Mitutoyo, Aurora, IL, USA). Because I. psammocola is not represented in the Chinese botany databases [54,98,99], its taxonomy is based on a comprehensive study of the protologue.

2.5. Taxonomy and Distribution

The conservative taxonomy of Iris was used [5,6,7,8,10,21,30,35,39,45,50,66,67,96]. For the nomenclature, the relevant articles and recommendations of the Shenzhen Code [100] were consulted. We used the name I. potaninii var. ionantha, as its taxonomy is controversial and needs further research (see Introduction).
In the Taxonomic Treatment section (see below), we gathered information on the distribution of the accepted species from our own field data, the herbarium specimens, and relevant literature [47] and critically assessed the collection points a priori from social networks [98,99,101,102,103].

3. Results

3.1. Genetic Divergence and Phylogenetic Relationships within Iris Sect. Psammiris

Four cpDNA regions were sequenced from 72 accessions of 10 I. sect. Psammiris species, 4 accessions of I. tigridia, 7 accessions of I. ivanovae, 2 accessions of I. goniocarpa, and 1 accession of I. potaninii var. ionantha, as well as from 2 samples of unknown species. A total of 18 haplotypes were identified among the samples from 10 species of I. sect. Psammiris, I. tigridia, and I. ivanovae based on polymorphic sites found at 3783 aligned positions of a combined dataset. The distribution of these haplotypes among the studied species is shown in Figure 2.
A total of 6 haplotypes (H1–H4, H6, and H7) were identified in 25 localities of I. potaninii, 3 haplotypes occurred in 17 localities of I. humilis (H9–H11), and 3 haplotypes occurred in 3 localities of I. kamelinii (H1, H3, and H8). Two haplotypes were found in I. psammocola (H1 and H5), I. arenaria (H12 and H13), I. schmakovii (H9 and H11), and I. ivanovae (H17 and H18); the following species showed one haplotype each: I. pineticola (H9), I. bloudowii (H15), I. mandshurica (H14), I. vorobievii (H16), and I. tigridia (H17). Of the six haplotypes found in I. potaninii, haplotype H7 was shared by the accessions from ZTLW, ZTLN, and ZAC; haplotypes H2 and H4 were shared by the accessions from two localities; and the accessions from the other 16 localities of I. potaninii shared a single common haplotype, i.e., H1. The latter was found to be common to three species: I. potaninii, I. psammocola, and I. kamelinii. Another haplotype (H3) was common to I. potaninii and I. kamelinii (localities MKS and MAK, respectively). Of the three haplotypes found in I. humilis, haplotype H9 proved to be the most frequent: it was shared by the accessions from 11 out of 17 localities. Moreover, this haplotype was also found in both studied localities of I. pineticola, while I. schmakovii shared two haplotypes (H9 and H11) with I. humilis.
The genealogical relationships between the haplotypes of the studied species are shown in Figure 4. All the haplotypes, including NAKH-01, NAKH-04, NAKH-07, KRAS-01, KRAS-04, KRAS-07, and ALT-03 retrieved from reference [34] and the haplotypes of I. goniocarpa and I. dichotoma, were connected in a single network. All of them, except for the haplotypes of I. goniocarpa, were closely related and originated from the same unsampled or extinct ancestral haplotype connected via many mutational steps with the haplotype of I. dichotoma. Three haplogroups were detected in the network, separated from each other by several mutational steps (six to eight). Haplogroup I included closely related haplotypes H1–H8 arranged into a star-like pattern around haplotype H1, which was common to I. potaninii, I. kamelinii, and I. psammocola. The pairwise FST values between these species were not significant (p > 0.1), no nucleotide substitutions or indels differentiating these species were revealed, and KS between them varied from 0.00006 to 0.00015, indicating a lack of genetic differences between these species.
The other two haplogroups (II and III) descended from a haplotype that may be either extinct or missing from the current sampling. The pairwise FST value between these groups was 0.782 (p = 0.00001), and the KS between them was 0.00126. Four nucleotide substitutions and 8 bp insertion distinguished the species from these groups. Haplogroup II included two haplotypes found in I. tigridia and I. ivanovae, of which one was common (H17) and the other (H18) was found only in samples from the I. ivanovae localities, differing from H17 by an insertion of 25 bp within the trnH-psbA spacer. The low and non-significant FST value (p > 0.05) between I. tigridia and I. ivanovae and the absence of sequence divergence between them (KS = 0.0000) may indicate that they belong to the same species.
Haplogroup III included 14 closely related haplotypes found in 7 species: I. arenaria, I. bloudowii, I. humilis, I. mandshurica, I. pineticola, I. schmakovii, and I. vorobievii. Haplotypes in this haplogroup differed from the neighboring haplotypes by one or two mutational steps. The most frequently occurring haplotype (H9) occupied a central position in this haplogroup and was common to most I. humilis accessions from different parts of the range, as well as to the accessions from the two I. pineticola localities and to one I. schmakovii accession (Figure 2 and Figure 4). Many haplotypes of haplogroup III were connected with H9 via one (H12 of I. arenaria, H14 of I. mandshurica, and H15 of I. bloudowii) or two mutational steps (H10, H11, and ALT-03 of I. humilis), forming a star-like structure. The haplotypes of I. mandshurica, which were interconnected via one or two mutational steps, were also closely related to the haplotypes of I. humilis. Alternative connections (loops in the network) between some haplotypes, including the most common haplotype (H9), indicated a homoplasy that hampered unambiguous identification of genetic relationships between the haplotypes of I. mandshurica and I. humilis. The haplotypes of I. vorobievii formed a group with a single haplotype of I. bloudowii (H15), which differed from the most common haplotype (H9) by a single substitution.
Trees with nearly identical topologies and with slight differences in statistical supports of some nodes were inferred by the MP, ML, and BI methods based on the cpDNA dataset (Figure 5). In these trees, all the accessions were distributed with a robust support (PP 1.0, BP > 90%) in accordance with their affiliation to the corresponding sections of the genus Iris. The sister-group relationship between I. sect. Pseudoregelia and I. sect. Psammiris was strongly supported (PP 1.00, BP 93, and 94%). The position of the CQM and CSJ accessions in the I. sect. Pseudoregelia group, together with I. goniocarpa and I. potaninii var. ionantha, was also strongly supported (PP 1.00, BP 99, and 100%).
The species of I. sect. Psammiris formed a monophyletic clade (PP 1.00, BP 99, and 100%), with I. tigridia and I. ivanovae nested within it. This clade was divided into two sister subclades, with the nucleotide divergence (KS) between them being 0.00182. Subclade I corresponded to haplogroup I revealed by the MJ methods (Figure 4) and included all the samples of I. potaninii, I. psammocola, and I. kamelinii, with moderate support (PP 0.94, BP 77, and 76%). Subclade II combined I. tigridia, I. ivanovae, and all other species recognized in I. sect. Psammiris (PP 1.00, BP 86, and 87%). This subclade, in turn, was divided into two well-supported clusters, of which one (cluster 2, support values of PP 1.0, BP 84, and 87%) contained the samples of I. tigridia and I. ivanovae, while the other (cluster 3, PP 1.0, BP 86, and 88%) included haplotypes of seven species (I. arenaria, I. bloudowii, I. humilis, I. mandshurica, I. pineticola, I. schmakovii, and I. vorobievii). These two clusters corresponded to haplogroups II and III revealed by the MJ methods. A low nucleotide divergence was observed between the species within cluster 3 (KS ranged from 0.00001 to 0.00088), and the relationships between I. arenaria, I. humilis, I. mandshurica, I. pineticola, and I. schmakovii remained unresolved. Only the haplotypes of I. bloudowii and I. vorobievii formed a group that received weak support from the MP and ML methods (BP 58, 53%) and high support only from the BI method (PP 0.96).
Thus, the results of this study based on sequencing of the cpDNA regions of 12 taxa show that I. sect. Psammiris includes five species (I. bloudowii, I. humilis, I. potaninii, I. tigridia, and I. vorobievii) and is divided into three groups.

3.2. Morphological Comparison of the Iris Sect. Psammiris Species

A detailed morphological comparison among the I. sect. Psammiris species accepted in the present study is listed in Table 2 (also see Table S1). They can be easily distinguished by the number of flowers and bracteoles, as well as by the stem height and perianth tube length.
Iris bloudowii, I. humilis, and I. vorobievii, forming a group of related species, are distinguished as having non-contractile, adventitious roots; thin and broad rosette leaves, usually with more than one flower and with bracteoles; tough green bracts; long pedicels; and a short perianth tube. Among them, I. humilis is similar to I. bloudowii but differs in its habit (less robust), number of bracteoles (from their absence to three; Figure 6a–c), and number of flowers (up to three; Figure 6b,c); moreover, it occasionally occurs in clumps (Figure 1c). In addition, a white-flowered form of I. humilis, a rare feature in this section, was found in Partizansky (S. Prokopenko, pers. comm.) and Khankaysky (A. Malyk, pers. comm.; Figure 1b) districts, Primorsky Krai, Russia. Iris vorobievii is characterized by a very short rhizome (up to 2 cm in length), storage-like roots spreading almost horizontally (Figure 6d,e), and often branched stems (e.g., VBGI79851; see http://botsad.ru/herbarium/, accessed on 20 December 2022).
Iris potaninii is similar to I. tigridia in the characters of roots (contractile), rosette leaves (ensiform, acute, or narrowly acute at the apex; tough; narrow; 0.1–0.6 cm wide), stem (with non-curled remains of leaves at the base, simple, 1-flowered, without bracteoles), bracts (lanceolate, whitish, and thin), pedicel (extremely short, less than 0.7 cm), and elliptical fruit. However, I. potaninii is distinguished from I. tigridia by its shortened, branching rhizomes; by having fibrous remains of leaves (vs. the rhizome surface glabrous); often forming large colonies or clumps (Figure 1g,h); by longer (up to 50 cm long), slightly less thickened roots; by a much shorter stem (to 2.5 cm long) not emerging above ground, resulting in fruit always being borne at the soil surface (Figure 6f,g); by having an extremely short internode between the upper cauline leaf and bracts (barely 0.2 cm long); and by its even longer perianth tube (usually more than two times as long as that of other species in the section). After opening, the color of I. potaninii flowers is bright yellow, subsequently turning into pale yellow (Figure 1g and Figure 6h, respectively). The species is variable in the color intensity of broken lines (brownish against yellow background) of the fall blade (Figure 6i–k), the shape (obovate or elliptic) of the inner perianth segments (or standards), in terms of whether they gradually or abruptly narrow into the claw (Figure 6i,j), and in terms of whether falls and standards have a notch at the apex (emarginated) (Figure 6i–k). Variability in these characters can be observed within the same locality or even clump.
Iris tigridia is clearly distinguished by its flower color, varying from pale blue to dark blue and purple or, rarely, white (Figure 1i–m and Figure 6l,m); however, it is never yellow as others in I. sect. Psammiris. Generally, it is variable (within a locality) in leaf length and width, stem height, and cauline leaf length (Table 2), as well as in floral diameter (3.5–6 cm).

4. Discussion

This study presents the most comprehensive phylogenetic analysis for I. sect. Psammiris of those carried out to date. The reported results provide new insights into the taxonomic composition and classification of this section. The samples represent almost all known taxa (a total of 12) in I. sect. Psammiris. Specimens of the species closely related to I. humilis (I. arenaria, I. pineticola, and I. schmakovii) and I. potaninii (I. kamelinii and I. psammocola) were included in the phylogenetic analysis for the first time. Our sampling of all the currently recognized species of I. sect. Psammiris from different parts of the ranges and type localities made it possible to clarify the genetic relationships between them, as well as with I. tigridia and I. ivanovae, which are now considered as representatives of I. sect. Pseudoregelia [1,11,67,68].
The monophyly I. sect. Psammiris has been questioned by other authors [14,50,51,66], since I. potaninii var. ionantha was shown to be related to I. sect. Pseudoregelia. The findings of this study clearly show that all the specimens of I. tigridia and its close relative, I. ivanovae, belong to the clade of I. sect. Psammiris (Figure 4 and Figure 5), which is monophyletic and sister to the clade formed by the taxa of I. sect. Pseudoregelia, including I. potaninii var. ionantha. The phylogenetic placement of I. potaninii var. ionantha is fully congruent with the tree topologies inferred in recent phylogenetic studies [14,50,51].
Within the I. sect. Psammiris clade, we revealed three well-supported monophyletic groups (haplogroups in the MJ network and clusters in the phylogenetic tree) treated by us at the series level, two of which we consider unispecific. The first group includes I. kamelinii, I. potaninii, and I. psammocola. These species have common or closely related haplotypes and demonstrate the lack of clear differentiation from each other (Figure 4 and Figure 5). Therefore, the first group can be considered unispecific. We choose I. sect. Psammiris ser. Potaninia Doronkin to represent the group, as it has the same type (I. potaninii) as Doronkin’s original group [11]. A thorough revision of the morphological characters previously proposed to distinguish between these species confirmed the lack of clear differences.
To date, eight species have been recognized in I. sect. Psammiris [15,17]. However, the taxonomic statuses of I. kamelinii, I. psammocola, I. arenaria, I. mandshurica, I. pineticola, and I. schmakovii, as well as I. ivanovae, are considered controversial.
The following diagnostic features were used to distinguish I. kamelinii from I. potaninii: rhizomes bear membranous remains of leaf bases (vs. fibrous remains); standards rounded–elliptic, emarginated at apex, abruptly narrowed into a linear claw (vs. obovate, gradually narrowed into a claw); and ornamentation of falls with a dense pattern of purple veins (vs. veins poorly visible) [61]. In the present study, we clearly showed that these features of I. kamelinii are identical or slightly differ from those of I. potaninii (see Section 3.2); thus, I. kamelinii does not have any diagnostic features that clearly distinguish it as a distinct species. It has long been noted that the standards in I. potaninii are usually emarginated at the apex [95,96,97]. Our data confirm that the standards in I. potaninii can be emarginated (or not) at the apex, even within the same plant from the type locality of I. kamelinii (Figure 6k); fall ornamentation is a variable character in I. potaninii (Figure 6i–k). As a consequence, we regard I. kamelinii as a synonym of I. potaninii.
The plants of I. psammocola from the Republic of Tuva, Russia [55], and the plants from the type locality of I. kamelinii [61] are found growing together with I. potaninii and all have the same chromosome number, i.e., 2n = 22 (see Introduction). In China (where I. psammocola was described), this species is known to date only from the protologue consisting of a diagnosis, a description, and an illustration [53]; from a single specimen deposited at NENU (NENU00014009!; Figure 7), which is a holotype of the name; and from reference [46]. The holotype of I. psammocola is represented by a small herb plant in flowering collected in early April. This specimen has a rhizome (broken) of about 0.5 cm in diameter; its adventitious roots are yellowish white, thickened at the proximal part, and gradually tapering to the apex, up to 20 cm long; the rosette leaves are ensiform, narrowly acute at the apex, tough, and finely ribbed, up to 18.5 cm long and 0.2–0.4 cm wide; the flowering stem is very short, not emerging above ground, probably not more than 2 cm tall (the height was impossible to measure), simple, bearing one terminal flower, and without bracteole; the stem and rhizome bear erect (non-curled) fibrous remains of leaves; two bracts are lanceolate and membranous; the pedicel is very short; the perianth tube is filiform, about 5 cm long; the outer perianth segments have a distinct beard, about 4.5 cm long. According to references [46,53], the rhizome of I. psammocola is short and non-stoloniferous, the bracts are 3.5–4 cm in length, and the flowers are yellow. After a critical examination of the I. psammocola protologue, we found that the features of the rhizome, roots, rosette leaves, flowering stem, bracts, and flowers are identical to those of I. potaninii (Table 2). Our analysis of cpDNA variability indicate the lack of genetic differences between the specimens of I. potaninii and the specimens from the Republic of Tuva, Russia, including the specimen (TTL) treated as I. psammocola (Figure 4 and Figure 5).
The phylogenetic analysis reported above (Figure 4 and Figure 5) confirmed that the plants from the type locality of I. tigridia and the plants from the Republic of Buryatia and Zabaykalsky Krai, here named as I. ivanovae, belong to the same species, I. tigridia, which is nested in I. sect. Psammiris and comprises a separate unispecific series. To describe I. ivanovae based on plants from Zabaykalsky Krai, Russia, the following diagnostic features were used to distinguish it from I. tigridia: flowers 2.5–3.5 cm in diameter (vs. flowers 4.0–6.0 cm in diameter); falls abruptly narrowed into a long, filiform claw (vs. falls gradually narrowed into a thin claw); bracts narrowly lanceolate, gradually acuminate (vs. bracts oblong-elliptical and short-pointed at the apex); and leaves gradually acuminate, 0.1–0.2 cm wide (vs. leaves shortly acuminate and 0.4–0.5 cm wide) [73]. However, our field study at the type locality of I. ivanovae did not confirm some of these features. We found that the flowers were mainly 3.5–6.0 cm in diameter, the falls were gradually (not abruptly) narrowed into a thin claw, 0.1 cm wide at the base, and the leaves were 0.1–0.3 cm wide (Figure 6l). The diameter of one of the ten flowers that we found was only 2.5 cm due to the underdeveloped blades of falls at the apex (Figure 6m). This plant can be considered merely an aberrant, which can be explained by the climatic conditions of the locality where it grew. In addition, we found that the lanceolate, gradually acuminate bracts are characteristic of all the plants of I. tigridia from Siberia, as well as the plants with leaves gradually narrowed to the apex. However, to the best of our knowledge, the latter dominate the Transbaikalian steppes and Mongolian habitats due to the rather xerophytic conditions. Furthermore, leaves in I. tigridia were previously characterized as gradually narrowed to the apex [45,95,96]. Thus, we did not find any differences between the plants from the type locality of I. ivanovae and the plants from the I. tigridia distribution range, which confirmed Gubanov’s opinion [76] that I. ivanovae is a synonym of I. tigridia.
The third group, revealed by the MJ methods and phylogenetic analyses of I. sect. Psammiris, comprises seven species: I. arenaria, I. bloudowii, I. humilis, I. mandshurica, I. pineticola, I. schmakovii, and I. vorobievii (Figure 4 and Figure 5). The isolated position of I. bloudowii and I. vorobievii in this group, along with the data on their morphology presented here (Table 2), are consistent with the results of previous studies [15,27,34,46,47,48] that showed them as separate species. Phylogenetic relationships between I. arenaria, I. humilis, I. mandshurica, I. pineticola, and I. schmakovii from Hungary, Ukraine, Mongolia, and Russia (Belgorod Oblast, Altai Krai, Altai Republic, Republic of Tuva, Republic of Buryatia, Zabaykalsky Krai, Amur Oblast, and Primorsky Krai) remain unresolved, and our results (the shared haplotypes and the star-like pattern) indicate a lack of clear genetic differentiation between them, which suggests that they belong to a single species, I. humilis.
The taxonomy of I. humilis has long been debated and based exclusively on traditional morphological study. An opinion existed that, having an extensive distribution range, I. humilis could not be homogenous; therefore, its numerous varieties were not considered as separate species [10,12,22,23]. Our data agree with the suggestion expressed by many authors on the taxonomy of I. arenaria [10,13,22,23,24,26,35], I. mandshurica [32,33], and I. pineticola [1,10,12,13,26,40] as taxonomic synonyms of I. humilis.
Iris humilis var. umbrosa was described based on plants collected on the right bank of Lake Khuvsgul, Khuvsgul Aimag, Mongolia. As follows from the brief description, it is a plant with a height of 20–30 cm; green linear–lanceolate leaves 3–8 mm wide ; yellow flowers with purple veins ; bracts coriaceus ; wide, swollen, acuminate, and fruit elliptical, tapering at the apex [70]. Unfortunately, the taxon I. humilis var. umbrosa was published without a diagnosis, and in our opinion, it is still unclear what distinguishes it from the autonymic variety. Moreover, all the features indicated in the protologue of I. humilis var. umbrosa and in reference [17] are identical to those of I. humilis (Table 2). All experts on the Mongolian flora listed I. humilis for the Khuvsgul phytogeographical region [27,74,75,76,77]. Despite the considerations mentioned above, Alexeeva referred to a “more detailed comparative morphological analysis of characters” (that she, however, never presented) and came to the conclusion that I. humilis var. umbrosa is actually a new species, I. schmakovii [17]. In accordance with the molecular data presented here, I. schmakovii belongs to I. humilis (Figure 4 and Figure 5).
It should also be noted that four cytotypes are known for I. humilis: 2n = 22, 24, 26, and 28. The following geographic pattern of the distribution of these cytotypes can be observed. For instance, the cytotype 2n = 22 has been recorded from the European part of the distribution range, e.g., from Ukraine (sub I. pineticola) [59] and Czech Republic (sub I. arenaria) [37]; 2n = 28 has been reported primarily from the central part of the distribution range, e.g., from Mongolia (sub I. flavissima) [104] as well as from Tomsk Oblast [105], Altai Republic [58], Republic of Tuva [60], Irkutsk Oblast [106], and Republic of Buryatia, Russia [45]; 2n = 24 has been reported from the eastern part of the distribution range, e.g., from the Republic of Buryatia [107] and Primorsky Krai (sub I. mandshurica) [108]. The cytotype 2n = 26 has been reported for Altai Republic, Russia (sub I. bloudowii) [57], and Jilin Province, China (sub I. bloudowii) [109]. In addition, two cytotypes, i.e., 2n = 24 and 2n = 28, have been recorded from plants collected at the same localities of Primorsky Krai, (sub I. mandshurica) [110,111] and Amur Oblast, Russia [58,112].

4.1. Taxonomic Treatment

In the present study, we propose I. sect. Psammiris to be divided into three series consisting of five species. In particular, we confirm that I. tigridia, the type species of I. sect. Pseudoregelia ser. Tigridiae [11], is nested in I. sect. Psammiris. Therefore, we suggest excluding I. ser. Tigridiae from I. sect. Pseudoregelia, as originally published in [11], and transferring it to I. sect. Psammiris. In addition, I. ser. Humiles Doronkin and I. ser. Vorobievia Alexeeva are synonymized here for the first time with the autonymic series of I. sect. Psammiris.
Moreover, as found in the present study, there are some problems related to the type citation in I. sect. Psammiris; therefore, the following issues should be addressed:
(i) Taylor indicated I. humilis as the type species of I. sect. Psammiris [9]. Since then, this approach has been accepted [11,12,14,15,71,113]. However, I. subgen. Psammiris was actually published by Spach as a monotypic taxon based on I. arenaria, although he noted this group to apparently also include I. flavissima and I. bloudowii as follows: “Huc referendae etiam videntur Iris flavissima, Jacq., et Iris Bloudowii, Ledeb.” [3]. We tend to interpret this phrase as non-inclusion of I. flavissima and I. bloudowii in I. subgen. Psammiris by Spach. He did not include these species in I. subgen. Psammiris either in the following study published four months later [114], which can be considered an indirect argument in favor of our opinion. The type of I. arenaria, not I. humilis, is therefore, the type of I. sect. Psammiris (see Art. 10.3 of the ICN).
(ii) The herbarium sheet at MW (MW0021793!) with a label handwritten by Georgi (“Iris pumila ad Baical, 1772”), which is the current lectotype of I. humilis [115], consists of four plants representing two species: I. pumila L. and I. humilis (as currently applied). When a type contains parts belonging to more than one taxon, the initial choice is superseded (see Art. 9.19 of the ICN), and the name must remain attached to the part that corresponds most nearly with the original description or diagnosis (Art.  9.14 of the ICN). Hence, because MW0021793 proved to be mixed and belong to more than one taxon, it cannot be accepted as a type of I. humilis, as previously proposed [115]. One of us (E.V. Boltenkov) numbered the plants belonging to I. humilis from the Lake Baikal area as 1 and 2, which was noted by Alexeeva [15], and the plants belonging to I. pumila of unknown origin as 3 and 4. However, Alexeeva [15] did not achieve the type designation because the typification statement did not include the phrase “designated here” or an equivalent (see Art. 7.11 of the ICN).
(iii) Contrary to the Alexeeva’s statements [116], the type of I. tigridia was not indicated by Grubov [27] (see Art. 40 Note 2). Similarly, the type designation of this name was not effectively published by Alexeeva [15,116], as required by Art. 7.11 of the ICN.
(iv) Iris pineticola was published [39] (p. 407) as a replacement name for I. flavissima subsp. stolonifera f. orientalis Ugr. Hence, the latter name is its replaced synonym (Art. 6.11 of the ICN) that has the same type as that of the replacement name (see Art. 7.4 of the ICN). Klokov indicated the specimen deposited at KW as the “typus speciei” of I. pineticola as follows: “RSS Ucr., dit. Charcoviensis, in pineto prope pag. Choroshevo, 5–6 V. 1855. Legit B.M. Czernjajev; in Herbario Instituti Botanici Ac. Sc. RSS Ucr. conservatur” [39]. While preparing his publication [22], Ugrinsky used the Vassilii Czernajew’s herbarium; therefore, Klokov’s indication could have been accepted as the lectotype for I. flavissima subsp. stolonifera f. orientalis, satisfying the requirements of Art. 7.11 of the ICN. However, Czernajew’s specimen cited by Klokov [39] was lost or destroyed, and for this reason, a neotype of I. pineticola (KW000114271) was selected (see Art. 9.16 of the ICN) [41]. Unfortunately, the authors of the latter paper did not consider all the original material in the context of the protologue of I. flavissima subsp. stolonifera f. orientalis (see Arts. 9.4 and 9.13 of the ICN), which contains an illustration [22] (p. 307). The same illustration was provided by Klokov in reference [39] (p. 293). In accordance with Art. 9.19 of the ICN, the choice of the neotype [41] should be superseded since the original material (illustration) was found to exist and can serve as lectotype.
As a consequence, lectotypes are designated here for I. flavissima subsp. stolonifera f. orientalis, I. humilis, and I. tigridia.

4.1.1. List of Taxa

Below is a list of the accepted species (highlighted in bold italics) that contains information on their synonyms and nomenclatural types, as well as on their distributions, habitats, and chromosome numbers.
Iris sect. Psammiris (Spach) J.J. Taylor, Proc. Biol. Soc. Washington 89(35): 417, 1976 ≡ I. subgen. Psammiris Spach, Ann. Sci. Nat., Bot., ser. 3, 5(1): 110, 1846.—Type species: Iris arenaria Waldst. et Kit.
(I) Iris ser. Psammiris
= Iris ser. Humiles Doronkin, Bot. Zhurn. 75(3): 415, 1990, syn. nov.—Type species: Iris humilis Georgi.
= Iris ser. Vorobievia Alexeeva, Phytotaxa 340(3): 205, 2018, syn. nov.—Type species: Iris vorobievii N.S. Pavlova.
(1) Iris humilis Georgi, Bemerk. Reise Russ. Reich 2: 196, 1775.—Lectotype (designated here by E.V. Boltenkov): [Russia, Irkutsk Oblast] ad Baikal, [fl.], 1772, [Georgi] s.n. Herb. C.B. Trinius (MW0021793!, sub “Iris pumila L.” det. J.G. Georgi).—https://plant.depo.msu.ru/open/public/en/item/MW0021793 (accessed on 20 December 2022).
= Iris flavissima Pall., Reise Russ. Reich. 3(2): 715, 1776.—Lectotype (designated by Alexeeva [115] (p. 917)): [Russia, Zabaykalsky Krai] Iris lutea biflorae affinis, Dahuria, [fl.], [June 1772], [Pallas] s.n. Herb. P.S. Pallas (BM000832584!).—https://data.nhm.ac.uk/dataset/collection-specimens/resource/05ff2255-c38a-40c9-b657-4ccb55ab2feb?q=BM000832584 (accessed on 20 December 2022).
= Iris mandshurica Maxim., Bull. Acad. Imp. Sci. Saint-Pétersbourg 26(3): 530, 1880.—Lectotype (designated by Alexeeva [116] (p. 417)): [Russia, Primorsky Krai], [handwritten by Goldenstädt]: In der Nähe von Nikolske, auf Sandboden, gelb, [fl.], 14 May 1872, [Goldenstädt] 19; [handwritten by C.J. Maximowicz]: Iris mandshurica Maxim. Suifun, Mandshuriae, Goldenstädt (LE01025688! cum icon, isolectotype LE01010784!).—http://re.herbariumle.ru/01025688 (accessed on 20 December 2022).
= Iris arenaria Waldst. et Kit., Descr. Icon. Pl. Hung. 1: 57, 1802 ≡ I. humilis subsp. arenaria (Waldst. et Kit.) Á.Löve et D.Löve, Bot. Not. 114(1): 51, 1961.—Lectotype (designated by Alexeeva [15] (p. 207)): [illustration] “Iris arenaria” in Waldstein et Kitaibel [117] (t. 57).—https://bibdigital.rjb.csic.es/records/item/11187-redirection (accessed on 20 December 2022).
= Iris flavissima subsp. stolonifera f. orientalis Ugr., Trudy Obsc. Isp. Prir. Imp. Har’kovsk. Univ. 44: 305, 1911 ≡ I. pineticola Klokov, Fl. URSR 3: 407, 1950.—Lectotype (designated here by E.V. Boltenkov): [illustration] “Iris flavissima Pall. I. B. orientalis Ugr.” in Ougrinsky [22] (p. 307).—https://www.biodiversitylibrary.org/item/26298#page/319/mode/1up (accessed on 20 December 2022).
= Iris humilis var. umbrosa Alexeeva, Turczaninowia 14(1): 59, 2011 ≡ I. schmakovii Alexeeva, Turczaninowia 21(4): 145, 2018, syn. nov.—Holotype: Mongolia, Khuvsgul Aimag, the right bank of the Khuvsgul Lake, 50°34′ N 100°28ʹ E, 1,738 m, [fr.], 6 July 2007, R.V. Kamelin et al. 23 [originally in Russian] (LE01042608!).—http://re.herbariumle.ru/01042608 (accessed on 20 December 2022).
Distribution and habitat: Iris humilis is the most widely distributed and northernmost of I. subgen. Iris and is the only arillate iris native to Europe. Its range stretches along the Eurasian steppe belt from Europe to the Pacific coast, including the steppe patches of southern Siberia and the Russian Far East. It is found from Central and Eastern Europe (northeastern Austria, southern Czech Republic, Hungary, northern Romania, Slovakia, and Ukraine), including the Central Black Earth Economic Region and eastern oblasts of the Volga region and Pre-Urals, to southern Siberia, Russia, and northern Kazakhstan, as well as in northern Mongolia, northeastern China (northeastern Inner Mongolia and Heilongjiang, Jilin, and Liaoning provinces), North Korea (Ryanggang, Jagang, and Kangwon provinces), southern Russian Far East, and eastwards to the Pacific coast, where it has been recorded from dunes near the Kievka River estuary (Primorsky Krai, Russia). The northernmost wild locality of I. humilis has been found in vicinities of Kochegarovo Village (Olekminskiy District, Yakutia, Russia, at approximately latitude 60° N; N.S. Danilova, pers. comm.). Iris humilis is characterized by good adaptation to sandy, stony, clayey, limestone, and humus-rich soils. It grows commonly in open places in steppes and meadows, on slopes, at edges of pine forests, and along river banks at elevations of 350–1850 m.
Chromosome numbers: 2n = 22, 24, 26, and 28 (see below).
(2) Iris bloudowii Ledeb., Icon. Pl. [Ledebour] 2: 5, 1830 ≡ I. flavissima α [var.] umbrosa Bunge, Fl. Altaic. [Ledebour] 1: 60, 1829, excl. syn. ≡ I. flavissima var. bloudowii (Ledeb.) Baker, Handb. Irid.: 29, 1892.—Lectotype (designated by Sennikov et al. [113] (p. 31)): [Kazakhstan, East Kazakhstan Region] ad Grammahuham [Gromotukha River], [fl.], 4 May 1826, [Ledebour] 95, Herb. C.F. Ledebour (LE01010770!, sub “Iris [flavissima, originally] bloudowii m.” det. Ledebour).—http://re.herbariumle.ru/01010770 (accessed on 20 December 2022).
Distribution and habitat: This species is found in the Altai-Sayan region, Northern Tian Shan (Dzhungraian Alatau and Kungey Alatau) and Inner Tian Shan (Terskey Ala-Too) and is distributed in northern Kyrgyzstan (Issyk-Kul Region), eastern Kazakhstan (East Kazakhstan, Jetisu, and Almaty regions), Russia (southern Altai Krai, Altai Republic, Republic of Khakassia, Republic of Tuva, southern Krasnoyarsk Krai), and northwestern China (Xinjiang). It grows on grassy subalpine and alpine meadows, among shrubs and in shady places, on hillsides or at forest edges, and along mountain streams at elevations of 850–2200 m.
Chromosome number: 2n = 16 [58,60].
(3) Iris vorobievii N.S.Pavlova, Sosud. Rast. Sovet. Dal’nego Vostoka 2: 424, 1987.—Holotype: [Russia] Primorsky Krai, Khasansky District, on the way to Kraskino Village, hill slopes, [fl.], 2 June 1964, Stepanova et al. s.n. [originally in Russian] (VLA00000320!; isotype VLA00000319!, sub “Iris mandshurica Maxim.” det. D.P. Vorobiev).—Figure 8.
Distribution and habitat: This species is known only from a limited area in southern Russian Far East (southern Khasansky District), northern North Korea, and northeastern China (northeastern Jilin Province). It is found growing in open places with good drainage, on loamy sand soil with gravel on grassy slopes, and on shingly meadow terraces near sea coasts at elevations up to 10 m.
Chromosome number: 2n = 14 (sub I. mandshurica) [108,109].
(II) Iris ser. Potaninia Doronkin, Bot. Zhurn. 75(3): 415, 1990.—Type species: Iris potaninii Maxim.
(4) Iris potaninii Maxim., Bull. Acad. Imp. Sci. Saint-Pétersbourg 26(3): 528, 1880.—Lectotype (designated by Alexeeva [116] (p. 417)): [Russia, Irkutsk Oblast] Dahuria, [fl.], 1830, [Turczaninow] s.n. Herb. C.F. Ledebour (LE01010785!, sub “Iris flavisima Pall.” det N.S. Turczaninow et “Iris potaninii Maxim. n. sp.” det. C.J. Maximowicz).—http://re.herbariumle.ru/01010785 (accessed on 20 December 2022).
= Iris potaninii var. arenaria Doronkin, Bot. Zhurn. 75(3): 415, 1990.—Holotype: [Russia, Buryatia Republic] Transbaikalia, near Troitskosavsk [Kyakhta], shtab-lekarskaya zaimka, at 10 versts from the city, [fl.], 21 May 1915, P. Mikhno s.n. [originally in Russian] (TK002363!, sub “Iris flavissima Pall.” det. P.S. Mikhno et “Iris bloudowii Ledeb.” det. L.P. Sergievskaya; isotype LE01072716!, sub “Iris flavissima Pall.” det. Mikhno et “Iris potaninii Maxim.” det. G.I. Rodionenko and V.I. Grubov).—Figure 9.
= Iris psammocola Y.T. Zhao, Acta Phytotax. Sin. 30(2): 181, 1992, syn. nov.—Holotype: [China] [Ningxia autonomous region, Lingwu County, Baijiatan], [fl.], 10 April 1959, s.coll. s.n. [originally in Chinese] (NENU00014009!).—Figure 7.
= Iris kamelinii Alexeeva, Novosti Sist. Vyssh. Rast. 38: 116, 2006, syn. nov.—Holotype: [Russia] Altai Republic, Kosh-Agachsky District, Chikhachev Range, Boguty Lake, the northern gravelly macroslope, 2500 m a.s.l., 6 July 2001, N.B. Alexeeva et al. 11 [originally in Russian] (LE01010775!).—http://re.herbariumle.ru/01010775 (accessed on 20 December 2022).
Distribution and habitat: It is distributed in the steppe patches of the southern Siberian mountain systems (Altai Republic, Republic of Khakassia, southern Krasnoyarsk Krai, Republic of Tuva, Republic of Buryatia, Irkutsk Oblast, and Zabaykalsky Krai, Russia), in Mongolia and China (northeastern and western Inner Mongolia, northwestern Heilongjiang Province, and the northern Ningxia autonomous region). The northernmost wild locality of I. potaninii known to us has been recorded from the upper Barguzin Depression in the Republic of Buryatia, Russia (54°27′16.5″ N 110°27′08.8″ E; see https://www.inaturalist.org/observations/136986666, accessed on 20 December 2022). As reported in [56], its range covers southern Mongolia from the Gobi-Altai Mountains, Bayankhongor Aimag (e.g., HAL0040724 and HAL0048583; see [103]), and the Gurvan Saikhan Mountains, Ömnögovi Province [118], to western Inner Mongolia and the Ningxia Hui Autonomous Region, China. It often grows in dry rocky, gravelly, or sandy places and on steppe slopes, dunes, and along perennial streams at elevations of 550–2800 m.
Chromosome number: 2n = 22 [55,57,58,59,60,61] (55 sub I. psammocola; 58,61 sub I. kamelinii).
(III) Iris ser. Tigridiae Doronkin, Bot. Zhurn. 75(3): 415, 1990.—Type species: Iris tigridia Bunge.
(5) Iris tigridia Bunge, Fl. Altaic. [Ledebour] 1: 60, 1829.—Lectotype (designated here by E.V. Boltenkov): [Russia, Altai Republic] Altai, in schistosis ad fluvium Tscharysch, [fl.], [4 May] 1826, Bunge 50, Herb. C.A. Meyer (LE01010797!, sub “Iris tigridia Bunge” det. A.A. Bunge).—http://re.herbariumle.ru/01010797 (accessed on 20 December 2022).
= Iris ivanovae Doronkin, Fl. Sibir. (Arac.-Orchidac.) 4: 117, 1987.—Holotype: [Russia, Zabaykalsky Krai] Chita Oblast, Borzinskiy District, Kharanor, feather-grass steppe, [fl.], 7 June 1965, A. Zarubin s.n. [originally in Russian] (NSK0000077!, sub “Iris tigridia Bunge” det. G.A. Peschkova).—https://www.jacq.org/detail.php?ID=525145 (accessed on 20 December 2022).
Distribution and habitat: This species is distributed in southern Siberia, Russia (southern Krasnoyarsk Krai and Republic of Khakassia, southeastern Altai Krai, Altai Republic, Republic of Tuva, southern Republic of Buryatia, and Zabaykalsky Krai), eastern Kazakhstan (East Kazakhstan Region), northern Mongolia, and China (Shanxi, Hebei, Jilin, and Liaoning provinces, Beijing, and Inner Mongolia). It grows in gravelly, stony, or sandy places in steppes among grasses, as well as on dunes, rocky slopes, and often on hilltops at elevations of 400–1200 m.
Chromosome numbers: 2n = 38 [58,59]. The other published chromosome numbers are 2n = 20, 24, 32, and 40 [57,60], though more studies will be needed to confirm these data.

4.1.2. The Key

Below is a key to the I. sect. Psammiris species recognized in the present study.
1. Stem > 2.5 cm tall, 1-flowered; perianth tube < 2.5 cm long; flowers of various shades of violet, blue, purple, and lilac . . . Iris tigridia
1′. Flowers yellow . . . 2
2. Stem < 2.5 cm tall, 1-flowered; perianth tube > 3.5 cm long . . . Iris potaninii
2′. Stem > 3.5 cm tall, several-flowered, simple or branched; perianth tube < 1.8 cm long . . . 3
3. Stem simple (2-flowered), or with 1–2 1-flowered branches; rhizome shortened; roots obconical, storage-like . . . Iris vorobievii
3′. Stem simple; rhizome creeping; roots gradually tapering to apex . . . 4
4. Stem with 2–3 flowers and 0–3 bracteoles . . . Iris humilis
4′. Stem with 2 flowers and 1 bracteole . . . Iris bloudowii

5. Conclusions

Although many specialists have carried out extensive studies of Iris sect. Psammiris, a number of taxonomic problems in this section remain unresolved. Here, we present the first comprehensive molecular phylogeny of the section, with a large set of samples covering most of the distribution ranges and type localities of the species and almost all of its previously recognized taxa. The results obtained in the present study confirm that all previous data, based solely on morphological characters, do not fully clarify the taxonomic composition and phylogenetic relationships among the I. sect. Psammiris species. Our results based on cpDNA data provide a number of novel insights. The important finding is that the phylogenetic results strongly support the monophyly of I. sect. Psammiris and the placement of I. potaninii var. ionantha in the I. sect. Pseudoregelia clade, which is sister to I. sect. Psammiris. It should also be emphasized that the taxonomy of I. potaninii var. ionantha requires further research. Furthermore, the molecular studies confirm the placement of I. tigridia in I. sect. Psammiris rather than in I. sect. Pseudoregelia.
Other our results are, in general, as follows: (1) five species (I. arenaria, I. humilis, I. mandshurica, I. pineticola, and I. schmakovii) should be treated as a single species, i.e., I. humilis; (2) the specimen listed in reference [55] as I. psammocola from Russia and other studied samples from the Tsugeer-Els area (Republic of Tuva, Russia), also referred to as I. psammocola, belong to I. potaninii; (3) a critical evaluation of the original material and literature showed that I. psammocola and I. potaninii are the same taxon; (4) the specimens of I. kamelinii from the type locality and from Mongolia [17] also belong to I. potaninii; (5) the molecular data and a critical examination of the type material and living plants from the type locality confirm that I. ivanovae, which has been recognized on the basis of morphology, is a synonym of I. tigridia. In view of the findings reported above, we provide an updated classification of I. sect. Psammiris. The section is unambiguously subdivided into an autonymic series with three species (the most widespread bearded iris I. humilis, I. bloudowii, and I. vorobievii) and two unispecific series: I. ser. Potaninia with I. potaninii and I. ser. Tigridiae with I. tigridia. Thus, here, we present a new taxonomic treatment for I. sect. Psammiris and an identification key for all of its species. The members of this section are distributed from southeastern Europe through southern Siberia, northern Kazakhstan, China, and Mongolia to the Russian Far East. The results presented herein will undoubtedly contribute to our understanding of the phylogenetic relationships within Iris s.l. and the taxonomic composition of the genus in Russia and adjacent areas.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/plants12061254/s1, Table S1: Raw data of the morphological analysis (the codes of the characters are provided in Abbreviations).

Author Contributions

Conceptualization, E.V.B.; methodology, E.V.B. and E.V.A.; software, E.V.B. and E.V.A.; validation, E.V.B. and E.V.A.; formal analysis, E.V.B. and E.V.A.; investigation, E.V.B. and E.V.A.; resources, E.V.B.; data curation, E.V.B.; writing—original draft preparation, E.V.B. and E.V.A.; writing—review and editing, E.V.B. and E.V.A.; visualization, E.V.B. and E.V.A.; supervision, E.V.B.; project administration, E.V.B. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The sequences resulting from this study are available in the NCBI database (https://www.ncbi.nlm.nih.gov/, accessed on 15 January 2023) with GenBank accession numbers ON569443–ON569794.

Acknowledgments

We are grateful to the curators and the staff of the consulted herbaria for making specimens available for our study and to Mingzhou Sun (NENU), Zoya Kozhevnikova (VLA), Irina Gureyeva (TK), and Marina Yarichina (LE) for having provided images of the specimens not available online. Special thanks are due to Christof Nikolaus Schröder (Heidelberg, Germany) for his kind assistance in deciphering the label of the I. mandshurica lectotype; to Zhao-Jun Bu (Northeast Normal University, Changchun, China) for his help in searching for Chinese literature sources; to Wenli Chen (PE) for his kind assistance in translating the label of the I. psammocola lectotype; to Dmitry German (South-Siberian Botanical Garden, Altai State University, Barnaul, Russia) and Marina Kozyrenko (Pushkin, Russia) for their helpful comments and suggestions; to Andrey Erst (Central Siberian Botanical Garden, Siberian Branch, Russian Academy of Sciences (SB RAS), Novosibirsk, Russia) and Denis Sandanov (UUH) for their kind cooperation in the botanical expeditions to southern Siberia; to Alexander Malyk (Primorskoye Lesnichestvo, Vladivostok, Russia) and Alexey Grebenjuk (LE), who generously provided and permitted the use of their photographs of irises; to Daba Chimitov (UUH), Nadezhda Danilova (Institute for Biological Problems of Cryolithozone, SB RAS, Yakutsk, Russia) and Yana Timofeeva and Sergey Prokopenko (Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch, Russian Academy of Sciences (FEB RAS), Vladivostok, Russia), who provided helpful information; and to Vera Neshataeva (Placemaking Europe) and Valentina Neshataeva (Komarov Botanical Institute, RAS, St. Petersburg, Russia) for logistical assistance with the I. arenaria samples. We are also grateful to Alexey Astashenkov and Yury Otmakhov (Central Siberian Botanical Garden, SB RAS, Novosibirsk, Russia), Natalia Shchegoleva (National Research Tomsk State University, Russia), Petr Kosachev (Altai State University, Barnaul, Russia), Andrey Dedov (citizen scientist, Altai Krai, Russia), Galina Darman (Amur Branch of the Botanical Garden-Institute, FEB RAS, Blagoveshchensk, Russia), Attila Mesterházy (Centre for Ecological Research, Debrecen, Hungary), Shukherdorj Baasanmunkh (Changwon National University, South Korea), Elena Chubar (A.V. Zhirmunsky National Scientific Center of Marine Biology, FEB RAS, Vladivostok, Russia), Mingzhou Sun (NENU), Sergey Zenin (citizen scientist, Bishkek, Kyrgyzstan), Alexey Grebenjuk, and Denis Sandanov for their help in gathering specimens. This study was carried out within the framework of institutional research project nos. 122040800085-4 and 121031000144-5.

Conflicts of Interest

The authors declare no conflict of interest.

Abbreviations

The following abbreviations are used in this manuscript. AMOVA, analysis of molecular variance; BI, Bayesian inference method; BL, bract length; BP, bootstrap percentage; CL, cauline leaf length; cpDNA, chloroplast deoxyribonucleic acid; FL, fruit length; FST, pairwise genetic distances; FW, fruit width; ICN, Shenzhen code; KS, nucleotide sequence divergence; LL, leaf length; LW, leaf width; MCMC, Markov chain Monte Carlo method; MJ, median-joining method; ML, maximum likelihood method; MP, maximum parsimony method; PCR, polymerase chain reaction; PL, pedicel length; PP, Bayesian posterior probability; RhD, rhizome diameter; RoD, root diameter; SH, stem height; TBR, tree bisection–reconnection.

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Figure 1. The species of Iris sect. Psammiris: (a) I. humilis, habit (Russia, Zabaykalsky Krai, vicinities of Ingoda Village); (b) I. humilis, a white-flowered form (Russia, Primorsky Krai, Khankaysky District); (c) I. humilis, in clump (Russia, Republic of Buryatia, Tarbagataysky District); (d) I. bloudowii, habit (Kazakhstan, Almaty Region, Dzhungraian Alatau); (e) I. vorobievii, habit (Russia, Primorsky Krai, vicinities of Kraskino); (f,g) I. potaninii, habit (Russia, Buryatia, vicinities of Novoselenginsk); (h) I. potaninii, in clump (Russia, Altai Republic, Kosh-Agach District, vicinities of Verkhniye Boguty Lake); (i–l) I. tigridia, flower color (Russia, Republic of Buryatia, Kyakhtinsky District, shtab-lekarskaya zaimka); (m) I. tigridia, a white-flowered form (Russia, Zabaykalsky Krai, vicinities of Khara-Byrka); (a,c,e–m) by E. Boltenkov, (b) by A. Malyk, (d) by A. Grebenjuk.
Figure 1. The species of Iris sect. Psammiris: (a) I. humilis, habit (Russia, Zabaykalsky Krai, vicinities of Ingoda Village); (b) I. humilis, a white-flowered form (Russia, Primorsky Krai, Khankaysky District); (c) I. humilis, in clump (Russia, Republic of Buryatia, Tarbagataysky District); (d) I. bloudowii, habit (Kazakhstan, Almaty Region, Dzhungraian Alatau); (e) I. vorobievii, habit (Russia, Primorsky Krai, vicinities of Kraskino); (f,g) I. potaninii, habit (Russia, Buryatia, vicinities of Novoselenginsk); (h) I. potaninii, in clump (Russia, Altai Republic, Kosh-Agach District, vicinities of Verkhniye Boguty Lake); (i–l) I. tigridia, flower color (Russia, Republic of Buryatia, Kyakhtinsky District, shtab-lekarskaya zaimka); (m) I. tigridia, a white-flowered form (Russia, Zabaykalsky Krai, vicinities of Khara-Byrka); (a,c,e–m) by E. Boltenkov, (b) by A. Malyk, (d) by A. Grebenjuk.
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Figure 2. Map showing the geographical origin of the Iris samples analyzed in the present study (composed using https://www.simplemappr.net, CC 1.0; accessed on 4 October 2022) and illustrating the distribution of cpDNA haplotypes: (a) the I. sect. Psammiris species, I. tigridia, and I. ivanovae; (b) the I. sect. Psammiris species. For locality and haplotype codes, see Table 1.
Figure 2. Map showing the geographical origin of the Iris samples analyzed in the present study (composed using https://www.simplemappr.net, CC 1.0; accessed on 4 October 2022) and illustrating the distribution of cpDNA haplotypes: (a) the I. sect. Psammiris species, I. tigridia, and I. ivanovae; (b) the I. sect. Psammiris species. For locality and haplotype codes, see Table 1.
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Figure 3. The type localities of irises are as follows: (a,b) I. kamelinii (Russia, Altai Republic, Kosh-Agach District, vicinities of Verkhniye Boguty Lake); (c,d) I. ivanovae (Russia, Zabaykalsky Krai, vicinities of Kharanor Village, together with Stipa krylovii); (a–c) by E. Boltenkov, (d) by D. Sandanov. Arrows indicate locations of irises.
Figure 3. The type localities of irises are as follows: (a,b) I. kamelinii (Russia, Altai Republic, Kosh-Agach District, vicinities of Verkhniye Boguty Lake); (c,d) I. ivanovae (Russia, Zabaykalsky Krai, vicinities of Kharanor Village, together with Stipa krylovii); (a–c) by E. Boltenkov, (d) by D. Sandanov. Arrows indicate locations of irises.
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Figure 4. Median-joining network inferred from combined sequences of the trnH-psbA, rps4-trnSGGA, trnS-trnG, and trnL-trnF regions showing the relationships among the cpDNA haplotypes of the Iris sect. Psammiris species, I. tigridia, I. ivanovae, and haplotypes of I. goniocarpa with I. dichotoma as outgroups. Each circle indicates a haplotype, with the size of the circle proportional to the number of localities where this haplotype was found. Black dots indicate nucleotide substitutions; thick white and black bars depict 1 bp and multi-base indels, respectively; the haplotypes outlined by dashed lines shows haplogroups I–III within I. sect. Psammiris. For haplotype codes, see Table 1.
Figure 4. Median-joining network inferred from combined sequences of the trnH-psbA, rps4-trnSGGA, trnS-trnG, and trnL-trnF regions showing the relationships among the cpDNA haplotypes of the Iris sect. Psammiris species, I. tigridia, I. ivanovae, and haplotypes of I. goniocarpa with I. dichotoma as outgroups. Each circle indicates a haplotype, with the size of the circle proportional to the number of localities where this haplotype was found. Black dots indicate nucleotide substitutions; thick white and black bars depict 1 bp and multi-base indels, respectively; the haplotypes outlined by dashed lines shows haplogroups I–III within I. sect. Psammiris. For haplotype codes, see Table 1.
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Figure 5. The Bayesian majority rule consensus tree of the Iris sect. Psammiris samples inferred from combined trnH-psbA, rps4-trnSGGA, trnS-trnG, and trnL-trnF chloroplast data. The numerals above the branches are Bayesian posterior probabilities (PP > 0.9) and bootstrap values (>50%) for the MP and ML methods. The haplotype and locality codes correspond to those listed in Table 1.
Figure 5. The Bayesian majority rule consensus tree of the Iris sect. Psammiris samples inferred from combined trnH-psbA, rps4-trnSGGA, trnS-trnG, and trnL-trnF chloroplast data. The numerals above the branches are Bayesian posterior probabilities (PP > 0.9) and bootstrap values (>50%) for the MP and ML methods. The haplotype and locality codes correspond to those listed in Table 1.
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Figure 6. Morphological features used for characterization of Iris sect. Psammiris: (a–c) I. humilis, inflorescence structure ((a,b) Russia, Zabaykalsky Krai, vicinities of the Orlyonok flag station; (c) Russia, Republic of Buryatia, Mount Spyashchiy Lev [bracts were removed]); (d,e) I. vorobievii, underground organs (Russia, Primorsky Krai, vicinities of Kraskino); (f,g) I. potaninii, in fruiting (Russia, Altai Republic, vicinities of Chagan-Uzun); (h–k) I. potaninii, flower morphology ((h) Russia, Republic of Buryatia, vicinities of Novoselenginsk; (i,j) Russia, Republic of Buryatia, vicinities of Gusinoye Lake; (k) (= I. kamelinii) Russia, Altai Republic, vicinities of Verkhniye Boguty Lake); (l,m) I. tigridia (= I. ivanovae), flowers (Russia, Zabaykalsky Krai, vicinities of Kharanor). Marks are as follows: 1, bract; 2, pedicel; 3, perianth tube; 4, bracteole; 5, rhizome; 6, adventitious root; 7, fruit; 8, bright yellow flower; 9, pale yellow flower; 10, blade of fall; 11, obovate standard; 12, gradually narrowing claw; 13, elliptic standard; 14, abruptly narrowing claw; 15, notch; 16, underdeveloped blade of fall. Photos by E. Boltenkov.
Figure 6. Morphological features used for characterization of Iris sect. Psammiris: (a–c) I. humilis, inflorescence structure ((a,b) Russia, Zabaykalsky Krai, vicinities of the Orlyonok flag station; (c) Russia, Republic of Buryatia, Mount Spyashchiy Lev [bracts were removed]); (d,e) I. vorobievii, underground organs (Russia, Primorsky Krai, vicinities of Kraskino); (f,g) I. potaninii, in fruiting (Russia, Altai Republic, vicinities of Chagan-Uzun); (h–k) I. potaninii, flower morphology ((h) Russia, Republic of Buryatia, vicinities of Novoselenginsk; (i,j) Russia, Republic of Buryatia, vicinities of Gusinoye Lake; (k) (= I. kamelinii) Russia, Altai Republic, vicinities of Verkhniye Boguty Lake); (l,m) I. tigridia (= I. ivanovae), flowers (Russia, Zabaykalsky Krai, vicinities of Kharanor). Marks are as follows: 1, bract; 2, pedicel; 3, perianth tube; 4, bracteole; 5, rhizome; 6, adventitious root; 7, fruit; 8, bright yellow flower; 9, pale yellow flower; 10, blade of fall; 11, obovate standard; 12, gradually narrowing claw; 13, elliptic standard; 14, abruptly narrowing claw; 15, notch; 16, underdeveloped blade of fall. Photos by E. Boltenkov.
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Figure 7. Holotype of Iris psammocola (NENU00014009) (included with permission of the curator).
Figure 7. Holotype of Iris psammocola (NENU00014009) (included with permission of the curator).
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Figure 8. Holotype of Iris vorobievii (VLA00000320) (included with permission of the curator).
Figure 8. Holotype of Iris vorobievii (VLA00000320) (included with permission of the curator).
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Figure 9. Holotype of Iris potaninii var. arenaria (TK002363), by permission of the Curator.
Figure 9. Holotype of Iris potaninii var. arenaria (TK002363), by permission of the Curator.
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Table
Table 1. Sampled Iris taxa with voucher information and GenBank accession numbers.
Table 1. Sampled Iris taxa with voucher information and GenBank accession numbers.
Code (Haplotype)Locality (Voucher *) **Coordinates:
° N, ° E		GenBank Accession Nos.
trnH-psbA/rps4-trnS/trnS-trnG/trnL-trnF
Iris subgen. Iris
I. psammocola Y.T.Zhao
TKY (H1)Russia, Tuva, Kyzyl, A.Yu. Astashenkov s.n. (VBGI)51.58211, 94.35711ON569443/ON569531/ON569619/ON569707
TTK (H1)Russia, Tuva, Lake Tore-Khol, A.Yu. Astashenkov s.n. (VBGI)50.15408, 95.13172ON569444/ON569532/ON569620/ON569708
TTR (H1)Russia, Tuva, near Tes River, A.Yu. Astashenkov s.n. (VBGI)49.98005, 95.52527ON569446/ON569534/ON569622/ON569710
TTL (H5)Russia, Tuva, Tsugeer-Els, D.N. Shaulo & V.M. Doronkin 17 (LE01072832)50.333333, 95.484722ON569445/ON569533/ON569621/ON569709
I. potaninii Maxim.
LBL (H1)Russia, Altai Republic, Kosh-Agach District, Lake Nizhniye Boguty, Boltenkov et al. 38 (VBGI)49.79277, 89.38888ON569447/ON569535/ON569623/ON569711
TAS1 (H1)Russia, Altai Republic, Kosh-Agach District, Tashanta, Boltenkov et al. 33 (VBGI)49.790833, 89.388611ON569448/ON569536/ON569624/ON569712
TAS2 (H1)Russia, Altai Republic, Kosh-Agach District, Tashanta, Boltenkov et al. 39 (VBGI)49.76333, 89.2375ON569449/ON569537/ON569625/ON569713
TAS3 (H1)Russia, Altai Republic, Kosh-Agach District, Tashanta, N.V. Shchegoleva s.n. (VBGI)49.73307, 89.1562ON569450/ON569538/ON569626/ON569714
TAS4 (H1)Russia, Altai Republic, Kosh-Agach District, 6 km north of Tashanta, P.A. Kosachev et al. s.n. (VBGI)49.75941, 89.19536ON569451/ON569539/ON569627/ON569715
SGR (H1)Russia, Altai Republic, Kosh-Agach District, near the Bol’shoy Sar-Gobo River estuary, R.V. Kamelin et al. 2613 (ALTB)49.66666, 89.09166ON569452/ON569540/ON569628/ON569716
ARC (H1)Russia, Altai Republic, Kosh-Agach District, Chagan-Uzun, Boltenkov et al. 24 (VBGI)50.06055, 88.29222ON569453/ON569541/ON569629/ON569717
ARU (H1)Russia, Altai Republic, Kosh-Agach District, Chagan-Uzun, Boltenkov et al. 26 (VBGI)50.0725, 88.41416ON569454/ON569542/ON569630/ON569718
CKR (H1)Russia, Altai Republic, Ongudaysky District, confluence of Chuya and Katun rivers, Boltenkov et al. 22 (VBGI)50.39722, 86.67444ON569458/ON569546/ON569634/ON569722
ARS (H1)Russia, Altai Republic, Ongudaysky District, Shashikman, Boltenkov et al. 19 (VBGI)50.78583, 86.06361ON569459/ON569547/ON569635/ON569723
KHA (H2)Russia, Altai Republic, Ongudaysky District, Khabarovka, I.M. Krasnoborov 188 (MHA)50.66666,
86.3		ON569460/ON569548/ON569636/ON569724
ARM (H2)Russia, Altai Republic, Mohro-Oyuk Pass, A.S. Revushkin et al. s.n. (LE)49.91769, 87.7311ON569461/ON569549/ON569637/ON569725
ACH (H4)Russia, Altai Republic, Kosh-Agach District, Kyzyl-Chin, P.A. Kosachev et al. s.n. (VBGI)50.06021, 88.29927ON569456/ON569544/ON569632/ON569720
ARK (H4)Russia, Altai Republic, Kosh-Agach District, 7 km west of Kuray, P.A. Kosachev et al. s.n. (VBGI)50.23663, 87.87082ON569457/ON569545/ON569633/ON569721
BNS (H1)Russia, Buryatia, Novoselenginsk, Boltenkov 57 (VBGI)51.01166, 106.64027ON569462/ON569550/ON569638/ON569726
BGL (H1)Russia, Buryatia, northeast of Lake Gusinoye, Boltenkov 62 (VBGI)51.21861, 106.51472ON569463/ON569551/ON569639/ON569727
BSA (H6)Russia, Buryatia, Sakhuli, D.G. Chimitov & O.V. Imetkhenova s.n. (UUH)54.41666, 110.4ON569464/ON569552/ON569640/ON569728
ZTLS (H1)Russia, Zabaykalsky Krai, southern bank of Lake Zun-Torey, Boltenkov 83 (VBGI)50.00222, 115.72055ON569465/ON569553/ON569641/ON569729
ZTLW (H7)Russia, Zabaykalsky Krai, northwestern bank of Lake Zun-Torey, Boltenkov 77 (VBGI)50.12972, 115.70361ON569466/ON569554/ON569642/ON569730
ZTLN (H7)Russia, Zabaykalsky Krai, north of Lake Zun-Torey, Boltenkov 80 (VBGI)50.1675, 115.81583ON569467/ON569555/ON569643/ON569731
ZAC (H7)Russia, Zabaykalsky Krai, Adon-Chelon, Boltenkov 91 (VBGI)50.46388, 116.0375ON569468/ON569556/ON569644/ON569732
MTB (H1)Mongolia, Tow Aimag, Bayan, Ch. Sanchir s.n. (LE)47.25111, 107.53833ON569469/ON569557/ON569645/ON569733
MTL (H1)Mongolia, Bayan-Olgii Aimag, Lake Tolbo, A.I. Shmakov & M.G. Kutsev s.n. (ALTB)48.536658, 90.050327ON569470/ON569558/ON569646/ON569734
MAT (H1)Mongolia, Arkhangai Aimag, 20 km south of Tsenkher Sum, I.A. Gubanov 255 (MW)47.44527, 101.75027ON569471/ON569559/ON569647/ON569735
MKS (H3)Mongolia, Khuvsgul Aimag, 25 km north of Sumber, A.L. Budantsev et al. 208 (MW)49.63333, 100.16694ON569472/ON569560/ON569648/ON569736
I. kamelinii Alexeeva
ABL (H1)Russia, Altai Republic, Kosh-Agach District, Lake Verkniye Boguty, Boltenkov et al. 34 (VBGI) **49.70583, 89.51333ON569455/ON569543/ON569631/ON569719
MAK (H3)Mongolia, Arkhangai Province, Khorgo Mountain, N.B. Alexeeva et al. 6 (LE01071966!)48.18888, 99.84833ON569473/ON569561/ON569649/ON569737
MKA (H8)Mongolia, Khuvsgul Aimag, between Khukhuu and Eg-Uur, N.B. Alexeeva et al. 36 (LE01071967!)50.57861, 100.78388ON569474/ON569562/ON569650/ON569738
I. bloudowii Ledeb.
KIT (H15)Kyrgyzstan, Issyk-Kul Region, northern slope of Terskey Ala-Too, A. Naumenko s.n. (VBGI)42.676717, 79.167452ON569475/ON569563/ON569651/ON569739
KAD (H15)Kazakhstan, Almaty Region, Dzhungraian Alatau, 10 km west of Qapal, A.V. Grebenjuk 161 (LE)45.02486, 78.94919ON569476/ON569564/ON569652/ON569740
AUY (H15)Russia, Altai Republic, Ust-Kansky District, Yaboganskiy Pass, Boltenkov et al. 15 (VBGI) **50.85194, 85.24194ON569477/ON569565/ON569653/ON569741
ASH (H15)Russia, Altai Republic, Shebalinsky Districtn, Shebalino, Boltenkov et al. 7 (VBGI)51.31611, 85.67972ON569478/ON569566/ON569654/ON569742
ASP (H15)Russia, Altai Republic, Ongudaysky District, ascent to the Seminsky Pass, Boltenkov et al. 40 (VBGI)50.94472, 85.74111ON569479/ON569567/ON569655/ON569743
SHA (H15)Russia, Altai Republic, Ongudaysky District, Shashikman, L. Lamanova s.n. (LE)50.7916, 86.05772ON569480/ON569568/ON569656/ON569744
AAR (H15)Russia, Altai Republic, Ongudaysky District, near the Aygulak River estuary, P.A. Kosachev et al. s.n. (VBGI)50.35986, 87.24423ON569481/ON569569/ON569657/ON569745
AKH (H15)Russia, Altai Republic, Ongudaysky Districtn, Khabarovka, Boltenkov et al. 20 (VBGI)50.66388, 86.29305ON569482/ON569570/ON569658/ON569746
ACT (H15)Russia, Altai Republic, Ongudaysky District, Chike-Taman Pass, Boltenkov et al. 21 (VBGI)50.64388, 86.31083ON569483/ON569571/ON569659/ON569747
AKA (H15)Russia, Altai Republic, Kosh-Agach District, Aktash, A. Dedov s.n. (VBGI)50.31111, 87.59916ON569484/ON569572/ON569660/ON569748
I. pineticola Klokov
UPO (H9)Ukraine, Poltava Oblast, Deimanivka, “Kukvyn”, pine forest, S.L. Zygalova et al. s.n. (KW) **50.21666, 32.63388ON569485/ON569573/ON569661/ON569749
UCH (H9)Ukraine, Cherkasy Oblast, Irdyn, pine forest, S.L. Zygalova et al. s.n. (KW) **49.36916, 31.67916ON569486/ON569574/ON569662/ON569750
I. humilis Georgi
BOU (H9)Russia, Belgorod Oblast, west of Urazovo, s. coll. s.n. (MHA)50.07861, 38.04805ON569487/ON569575/ON569663/ON569751
CHU (H9)Russia, Altai Krai, Bayevsky District, Chumanka, A. Dedov s.n. (VBGI)53.5, 80.45ON569496/ON569584/ON569672/ON569760
AAB (H10)Russia, Altai Republic, Ongudaysky District, Ak-Boom, N.V. Shchegoleva s.n. (VBGI)50.21429, 87.32491ON569504/ON569592/ON569680/ON569768
CCK (H10)Russia, Altai Republic, Ongudaysky District, confluence of Chuya and Katun rivers, Boltenkov et al. 22 (VBGI)50.39722, 86.67444ON569505/ON569593/ON569681/ON569769
ABR (H10)Russia, Altai Republic, Ongudaysky District, Ak-Boom Rock, Boltenkov et al. 23 (VBGI)50.35361, 87.05694ON569506/ON569594/ON569682/ON569770
AKC (H10)Russia, Altai Republic, Kosh-Agach Districtn, between Kurai and Chagan-Uzun, Boltenkov et al. 28 (VBGI)50.16944, 88.20861ON569507/ON569595/ON569683/ON569771
ATR (H10)Russia, Altai Republic, Kosh-Agach District, 1 km west of the Tydtugem River estuary, P.A. Kosachev et al. s.n. (VBGI)50.18732, 88.12405ON569508/ON569596/ON569684/ON569772
TTD (H9)Russia, Tuva, Tandinsky District, Lake Dus-Khol’, Yu.S. Otmakhov 8 (VBGI)51.35563, 94.45398ON569497/ON569585/ON569673/ON569761
TDL (H9)Russia, Tuva, Lake Dus-Khol’, Yu.S. Otmakhov 40 (VBGI)51.35604, 94.44693ON569498/ON569586/ON569674/ON569762
BSL (H9)Russia, Buryatia, Tarbagataysky District, Mount Spyashchiy Lev, Boltenkov 63 (VBGI)51.53833, 107.34611ON569491/ON569579/ON569667/ON569755
BBB (H9)Russia, Buryatia, Bichursky District, Bichura, Boltenkov 112 (VBGI)50.62888, 107.66472ON569492/ON569580/ON569668/ON569756
BTM (H9)Russia, Buryatia, Tunkinsky District, Mondy, D.V. Sandanov s.n. (VBGI)51.69760, 100.86766ON569493/ON569581/ON569669/ON569757
BCR (H11)Russia, Buryatia, Kyakhtinsky District, Chikoy River, Khilgantuy, Boltenkov 114 (VBGI) **50.44944, 106.91ON569494/ON569582/ON569670/ON569758
ZIO (H9)Russia, Zabaykalsky Krai, Ingoda River, Orlenok, E.V. Boltenkov 109 (VBGI) **51.74722, 113.84638ON569488/ON569576/ON569664/ON569752
ZIV (H9)Russia, Zabaykalsky Krai, Ingoda River, Ingoda Village, Boltenkov 110 (VBGI) **51.83055, 113.08638ON569489/ON569577/ON569665/ON569753
ZIL (H9)Russia, Zabaykalsky Krai, Ingoda River, Lesnoi Gorodok, Boltenkov 111 (VBGI) **51.66722, 112.98166ON569490/ON569578/ON569666/ON569754
AMH (H9)Russia, Amur Oblast, Novotroitskoe Village, G.F. Darman s.n. (VBGI)50.428889, 127.549806ON569495/ON569583/ON569671/ON569759
ALT-03Russia, Altai Republic, Ongudaysky District, Chuya River estuary, L.M. Pshennikova s.n. (VBGI, cult.)–FM253737/FM253420/FM864187/FM863912
I. arenaria Waldst. et Kit.
HGY (H12)Hungary, Győrszentiván, 24.04.2020, A. Mesterházy s.n. (VBGI) **47.69777, 17.73638ON569501/ON569589/ON569677/ON569765
HCS (H12)Hungary, Csákvár, A. Mesterházy s.n. (VBGI) **47.39332, 18.46049ON569502/ON569590/ON569678/ON569766
HBU (H13)Hungary, Bugac, 28.07.2020, B. Zoltán s.n. (VBGI) **46.65944, 19.59880ON569503/ON569591/ON569679/ON569767
I. schmakovii Alexeeva
MKK (H9)Mongolia, Khuvsgul Aimag, Khatgal Sum, Sh. Baasanmunkh s.n. (VBGI) **50.61924, 100.51207ON569499/ON569587/ON569675/ON569763
MKH (H11)Mongolia, Khuvsgul Aimag, Lake Khuvsgul, R.V. Kamelin et al. 23 (LE) **50.56666, 100.46666ON569500/ON569588/ON569676/ON569764
I. mandshurica Maxim.
GSS (H14)Russia, Primorsky Krai, Oktyabrsky District, Mount Sen’kina Shapka, Boltenkov s.n. (VBGI) **43.91833, 131.65943ON569510/ON569598/ON569686/ON569774
SRS (H14)Russia, Primorsky Krai, Oktyabrsky Districtn, Sinel’nikovo-1, Boltenkov s.n. (VBGI) **43.96, 131.53361ON569511/ON569599/ON569687/ON569775
GSM (H14)Russia, Primorsky Krai, Nakhodka, Mount Sestra, Boltenkov s.n. (VBGI)42.82777, 132.99499ON569509/ON569597/ON569685/ON569773
PPE (H14)Russia, Primorsky Krai, Partizansky District, Ekaterinovka, Boltenkov 123 (VBGI)42.91527, 133.04944ON569512/ON569600/ON569688/ON569776
NAKH-01
NAKH-04		Russia, Primorsky Krai, vicinities of Nakhodka, R.V. Dudkin s.n. (VBGI, cult.)–FM253719/FM253402/FM864169/FM863894
FM253722/FM253405/ FM864173/FM863897
NAKH-07FM253725/FM253408/FM864175/FM863900
I. vorobievii N.S.Pavlova
KKR (H16)Russia, Primorsky Krai, Khasansky District, Kraskino, Boltenkov s.n. (VBGI) **42.725, 130.93361ON569514/ON569602/ON569690/ON569778
KBR (H16)Russia, Primorsky Krai, Khasansky District, Bay Pemzovaya, E.A. Chubar s.n. (VBGI)42.54667, 130.83971ON569513/ON569601/ON569689/ON569777
KRAS-01Russia, Primorsky Krai, Khasansky District, Kraskino, R.V. Dudkin s.n. (VBGI, cult.) **–FM253702 /FM253385/FM864152/FM863877
KRAS-04FM253705/FM253388/FM864155/FM863880
KRAS-07FM253708/FM253391/FM864158/FM863883
I. tigridia Bunge
ACR (H17)Russia, Altai Republic, Ust-Kansky District, right bank of Charysh River, Vladimirovka, Boltenkov et al. 11 (VBGI) **51.05388, 84.19ON569515/ON569603/ON569691/ON569779
AUT (H17)Russia, Altai Republic, Ust-Kansky District, 3 km west of Tiudrala, Boltenkov et al. 10 (VBGI)51.01, 84.44138ON569516/ON569604/ON569692/ON569780
ARY (H17)Russia, Altai Republic, Ongudaysky District, 12 km west of Yelo, Boltenkov et al. 17 (VBGI)50.79055, 85.35777ON569517/ON569605/ON569693/ON569781
AUS (H17)Russia, Altai Republic, Ust-Kansky District, east of Ust-Kan, Boltenkov et al. 13 (VBGI)50.94722, 84.82944ON569518/ON569606/ON569694/ON569782
I. ivanovae Doronkin
BNV (H17)Russia, Buryatia, Novoselenginsk Village, Boltenkov 58 (VBGI)51.01166, 106.64027ON569523/ON569611/ON569699/ON569787
BAZ (H18)Russia, Buryatia, Kyakhtinsky District, shtab-lekarskaya zaimka, Boltenkov 59 (VBGI)50.38027, 106.55861ON569524/ON569612/ON569700/ON569788
BMK (H18)Russia, Buryatia, Maly Kunaley Village, Boltenkov 113 (VBGI)50.61361, 107.83111ON569525/ON569613/ON569701/ON569789
ZKL (H17)Russia, Zabaykalsky Krai, Aginsky District, Lake Khaptsagaytuy, Boltenkov 72 (VBGI)50.6167, 114.88777ON569520/ON569608/ON569696/ON569784
ZKV (H18)Russia, Zabaykalsky Krai, Kharanor Village, Boltenkov 93 (VBGI) **50.04666, 116.8225ON569521/ON569609/ON569697/ON569785
ZBT (H18)Russia, Zabaykalsky Krai, Bol’shaya Tura Village, Boltenkov 66 (VBGI)51.63111, 114.0383ON569519/ON569607/ON569695/ON569783
ZSM (H18)Russia, Zabaykalsky Krai, Soktui-Milozan Village, Boltenkov 102 (VBGI)50.09916, 117.85861ON569522/ON569610/ON569698/ON569786
I. goniocarpa Baker
CSSChina, Sichuan, Songpang County, Shuijing Village, T.G. Elumeeva s.n. (MW0735242)32.98123, 103.68576ON569526/ON569614/ON569702/ON569790
CGJChina, Gansu, Jonê County, Wanmaoxiang, SQAE 85 (E)34.8013, 103.20255ON569527/ON569615/ON569703/ON569791
I. potaninii var. ionantha Y.T.Zhao
CQXChina, Qinghai, Xinghai County, northern slope of Jiangluling, D.G. Long et al. 148 (E00141064!)35.56576, 99.98481ON569530/ON569618/ON569706/ON569794
Iris sp.
CQMChina, Qinghai, Madoi County, Heihe Town, M. Sun s.n. (NENU)34.797384, 98.133337ON569528/ON569616/ON569704/ON569792
CSJChina, Sichuan, Jiulong County, Tributary valley SW of Jiulong – Wuxuhai road, s.coll. 342 (E00424870!)28.96863, 101.40036ON569529/ON569617/ON569705/ON569793
Outgroup specimens
I. subgen. Pardanthopsis (Hance) Baker
I. dichotoma Pall.Russia, Amur Oblast, M. Baranova s.n. (LE, cult.)–LT978555/LT981297/LT984447/LT984483
I. subgen. Limniris (Tausch) Spach
I. ser. Lacteae Doronkin
I. lactea Pall.Russia, Zabaykalsky Krai, Kharanor,
Chernova s.n. (IRK)		–LT627854/LN871708/LN871662/LN871625
I. oxypetala BungeChina, Shaanxi, Suyde, Kabanov s.n. (LE)–LT627844/LT627950/LT627975/LT627911
I. tibetica (Dykes) Bolt.China, Qinghai, Xining to Ta Er, Long et al. 3 (E)–LT627893/LT627939/LT627998/LT627933
I. ser. Laevigatae (Diels) G.H.M.Lawr.
I. ensata Thunb.Russia, Primorsky Krai, Zarubino,
Boltenkov s.n. (VBGI)		–LT628002/LT628022/LT628012/LT627896
I. laevigata Fisch.Russia, Primorsky Krai, Roshchino,
Pshennikova s.n. (VBGI)		–LT628003/LT628024/LT628013/LT627897
I. pseudacorus L.Russia, Vladivostok, Boltenkov s.n.
(VBGI)		–LT628004/LT628025/LT628014/LT627898
I. ser. Ruthenicae (Diels) G.H.M.Lawr.
I. unifloraRussian Federation, Primorsky Krai, Zarubino, Boltenkov s.n. (VBGI)–LT628002/LT628022/LT628012/LT627896
I. ser. Sibiricae (Diels) G.H.M.Lawr.
I. sibirica L.Mongolia, Dornod, Bayan-Uul, Gubanov 550 (MW)–LT978556/LT981298/LT984448/LT984480
I. bulleyana DykesChina, Yunnan, Zhongdian, M.G. Pimenov et al. 432 (MW)–LT627895/LT628011/LT628021/LT628001
I. bulleyana f. chrysographes (Dykes) Bolt.China, Sichuan, Jiulong, Sichuan
Expedition 331 (E)		–LR597328/LR597344/LR597360/LR597376
I. bulleyana f. forrestii (Dykes) Bolt.China, Yunnan, Lijiang, Yulong Xueshan, P. Cox et al. 2633 (E, cult.)–LT978553/LT981295/LT984445/LT984478
I. delavayi MicheliChina, Yunnan, Dali Xian, Yinglofen, Sino-Amer. Bot. Expedition 959 (MHA)–LT978552/LT981294/LT984444/LT984477
I. clarkei Baker ex Hook.f.Nepal, Trogsindho Pass, E.F. Needham 674 (E, cult.)–LR597338/LR597354/LR597370/LR597386
I. wilsonii C.H.WrightChina, Yunnan, Little Zhongdian, E.J. Cowley 566 (Kew no. 1990-3457, cult.)–LR597339/LR597355/LR597371/LR597387
* Herbarium codes are according to Index Herbariorum [83]. ** Specimen collected in/near the type locality. A dash (“–”) indicates that data were not provided. The accession numbers highlighted in italics are reported in references [34,80,81,82]. Cult., cultivated.
Table
Table 2. Morphological characteristics of the Iris sect. Psammiris species.
Table 2. Morphological characteristics of the Iris sect. Psammiris species.
No.CharacterI. humilisI. bloudowiiI. vorobieviiI. potaniniiI. tigridia
1Rhizome shapeCreepingCreepingShortenedCompactCreeping
2Rhizome diameter0.35–0.80.4–10.5–10.45–10.25–0.65
3Root shapeEqualEqualObconicalContractileContractile
4Root diameter0.05–0.20.06–0.240.12–0.270.07–0.340.12–0.44
5Leaf shapeEnsiform or subfalcateSubfalcateSubfalcateEnsiformEnsiform or subfalcate
6Leaf apexAcute, straight or incurvedAcute, incurvedAcute, incurved or straightNarrowly acute, straight or incurvedNarrowly acute or acute, straight
7Leaf textureThin, smoothThin, smoothThin, ribbedTough, smoothTough, smooth
8Leaf length10.5–3021–5019–605–299.5–30
9Leaf width0.2–1.70.4–1.80.5–1.70.1–0.50.1–0.6
10Stem height2–19.56–28.56–250.5–2.52.5–20
11Stem branching000–200
12Number of flowers2–31–22–411
13Cauline leaf length4.3–1411–195.2–13.52.5–63–10
14Number of bracteoles(0) 1–31100
15Bract length2–5.62.5–5.62.5–6.52.5–63–4.5
16Bract textureToughToughToughThinThin
17Pedicel length0.2–30.8–60.5–1.50–0.20–0.7
18Tube length0.5–1.50.9–1.80.5–1.63.5–5.71.5–2.5
19Flower colorYellow (white)YellowLight yellowYellow Blue to violet (white)
20Fruit length2.7–6.53.3–6.55.2–6.52–42–4
21Fruit width1–21.3–2.51.2–2.40.8–20.8–1.8
22Fruit shapeElliptical, tapering at apexEllipticalOblong-elliptical, tapering at apexElliptical, apex obtuseElliptical, tapering at apex
All measurements are in centimeters. See Supplementary raw data in Table S1 for more details. Descriptions of the characters are provided in Section 2.4; for illustrations, see Figure 1 and Figure 6.
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Boltenkov, E.V.; Artyukova, E.V. New Approach to the Systematics of the Section Psammiris (Iris, Iridaceae): What Does Chloroplast DNA Sequence Tell Us? Plants 2023, 12, 1254. https://doi.org/10.3390/plants12061254

AMA Style

Boltenkov EV, Artyukova EV. New Approach to the Systematics of the Section Psammiris (Iris, Iridaceae): What Does Chloroplast DNA Sequence Tell Us? Plants. 2023; 12(6):1254. https://doi.org/10.3390/plants12061254

Chicago/Turabian Style

Boltenkov, Eugeny V., and Elena V. Artyukova. 2023. "New Approach to the Systematics of the Section Psammiris (Iris, Iridaceae): What Does Chloroplast DNA Sequence Tell Us?" Plants 12, no. 6: 1254. https://doi.org/10.3390/plants12061254

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