Cytogeography of Solidago sect. Erectae, sect. Villosicarpae , sect. Squarrosae , and sect. Brintonia (Asteraceae: Astereae)

: Chromosome numbers are reported for 67 individuals of 13 species of Solidago sect. Erectae , S. sect. Squarrosae , and S. sect. Villosicarpae from 65 locations in eastern Canada and the eastern United States: S. bicolor , S. erecta , S. hispida , S. jejunifolia , S. pallida , S. puberula , S. pulverulenta , S. rigidiuscula , S. roanensis , S. sciaphila , S. speciosa , S. squarrosa , and S. villosicarpa . Cytogeography maps based on new reports and all 258 previously published reports from 230 locations for the three sections plus S. sect. Brintonia ( S. discoidea ) are presented for 20 of the 30 species in the four closely related sections. The following are either ﬁrst documented reports for the taxon or just ﬁrst counts for a taxon from particular provinces and states: Solidago bicolor , 2 n = 18 from Nova Scotia and Prince Edward Island; S. hispida var. hispida , 2 n = 18 from New Hampshire, New Brunswick, and Wisconsin; S. jejunifolia , 2 n = 18 from Michigan and Minnesota; S. pallida , 2 n = 18 from Wyoming; S. puberula , 2 n = 18 from Pennsylvania, Prince Edward Island, and Virginia; and ﬁrst reports for S. sciaphila , 2 n = 36 from Iowa, Illinois, and Wisconsin.


Introduction
Solidago sect. Erectae G. Don in Loudon is the second largest section in the genus with 26 species that are native to a range of habitats mostly in eastern North America varying from moist woods and wood margins to open sandy barrens and dunes, sandstone and limestone cliff tops and faces, and disturbed soil habitats such as roadsides and fields (Semple and Beck 2021 [1], Semple 2022 [2]). The section is defined by having lower stem and basal rosette leaves that are the largest on the plant and usually narrow elongated wand-shaped to club-shaped inflorescences and involucres and upper vegetative parts that are sometimes somewhat to obviously resinous. Most of the species were included in S. subsect. Squarrosae A. Gray and S. subsect. Humiles (Rydb.) Semple in Flora North America (Semple and Cook 2006 [3]). The number of species and varieties recognized in the section(s) or subsection(s) has differed among authors (Small 1903 [4], Fernald 1908 [5], Fernald 1915 [6], Fernald 1936 [7], Fernald 1950 [8], Radford et al., 1968 [9]) and over time by the same author or authors (e.g., Cronquist 1968 [10], Cronquist 1980 [11]; Semple et al., 2017a [12], Semple et al., 2017b [13], Semple et al., 2017c [14], Semple et al., 2020 [15], Semple and Nelson 2018 [16]) with 26 species recognized most recently [1]. Semple and Cook [3] adopted much of Cronquist's treatments [10,11] of taxa in their subsect. Squarrosae and recognized 9 species. Subsequent multivariate morphometric analyses [12][13][14][15] resulted in the breaking up of the S. speciosa complex into four separate species based on morphological and habitat preference differences of what had been treated as four varieties within the species and the breaking up of the S. puberula complex. Most recently Semple and Beck [1] presented a revised infrageneric classification based on an unpublished (currently in review) polygenomic DNA sequence data analysis that resulted

Materials and Methods
Meiotic counts (2n = 9 II , 2n = 18 II , 2n = 27 II ) were made from pollen mother cells dissected from buds fixed in the field in 3:1/EtOH: glacial acetic acid and subsequently stored under refrigeration in 70% EtOH. Mitotic counts (2n = 18, 2n = 36, 2n = 54) were made from root tip cells taken from transplanted wild rootstocks or from seedlings grown from cypselae collected in the wild. Root tips were pretreated in 0.01% colchicine or saturated P.D.B. for 2-3 h, fixed in either Modified Carnoy's Fixative (4:3:1/chloroform: EtOH: glacial acetic acid) or Acetic Alcohol Fixative (3:1/EtOH: glacial acetic acid) and hydrolyzed in 1N HCl for 30 min at 60 • C before squashing. Anther sacs containing pollen mother cells and meristematic root tips were squashed in 1% acetic orcein, and counts of chromosomes were made from freshly prepared material. Herbarium vouchers for all new counts are deposited in WAT in MT unless otherwise indicated. Identifications were made by J.C.S. and follow the nomenclature in Semple and Beck [1].
Vouchers for previously published counts were borrowed from or examined at MT and WAT [41] or examined online using SERNEC [42]. In some cases, the cited voucher for a count could not be located and the likelihood that the identification was correct was assessed by examining other specimens of the same taxon collected by the author of the count from the same or approximately the same location.

Results
Identifications of vouchers were confirmed or revised for nearly all of the 258 previously published chromosome number reports from 230 locations for taxa in Solidago sect. Erectae (except subsect. Humiles), S. sect. Squarrosae, S. sect. Villosicarpae and S. sect. Brintonia and are listed in Appendix A. The previous report of 2n = 18 for S. hispida (Hooper 83091001 WAT [26]) was determined to be the first report for S. hispida Muhl. aff. var. lanata (Hook.) Fernald. Chromosome counts are reported for the first time in Appendix B for 67 individuals from 65 locations in eastern Canada and the eastern United States for 13 species of Solidago sect. Erectae, S. sect. Squarrosae, and S. sect. Villosicarpae. The following are either first documented reports for the taxon or for the taxon for particular provinces and states: Solidago bicolor, 2n = 18 from Nova Scotia and Prince Edward Island; S. hispida var. hispida, 2n = 18 from New Hampshire, New Brunswick, and Wisconsin; S. jejunifolia, 2n = 18 from Michigan and Minnesota; S. pallida, 2n = 18 from Wyoming; S. puberula, 2n = 18 from Pennsylvania, Prince Edward Island, and Virginia; and first reports for S. sciaphila, 2n = 36 from Iowa, Illinois, and Wisconsin. All 325 chromosome number counts from 295 locations for all taxa in Solidago sect. Erectae (except subsect. Humiles), S. sect. Squarrosae, S. sect. Villosicarpae and S. sect. Brintonia were used to create cytogeography maps for these taxa (Figures 1-9).
Taxonomy 2022, 2, FOR PEER REVIEW 3 for a count could not be located and the likelihood that the identification was correct was assessed by examining other specimens of the same taxon collected by the author of the count from the same or approximately the same location.

Results
Identifications of vouchers were confirmed or revised for nearly all of the 258 previously published chromosome number reports from 230 locations for taxa in Solidago sect. Erectae (except subsect. Humiles), S. sect. Squarrosae, S. sect. Villosicarpae and S. sect. Brintonia and are listed in Appendix A. The previous report of 2n = 18 for S. hispida (Hooper 83091001 WAT [26]) was determined to be the first report for S. hispida Muhl. aff. var. lanata (Hook.) Fernald. Chromosome counts are reported for the first time in Appendix B for 67 individuals from 65 locations in eastern Canada and the eastern United States for 13 species of Solidago sect. Erectae, S. sect. Squarrosae, and S. sect. Villosicarpae. The following are either first documented reports for the taxon or for the taxon for particular provinces and states: Solidago bicolor, 2n = 18 from Nova Scotia and Prince Edward Island; S. hispida var. hispida, 2n = 18 from New Hampshire, New Brunswick, and Wisconsin; S. jejunifolia, 2n = 18 from Michigan and Minnesota; S. pallida, 2n = 18 from Wyoming; S. puberula, 2n = 18 from Pennsylvania, Prince Edward Island, and Virginia; and first reports for S. sciaphila, 2n = 36 from Iowa, Illinois, and Wisconsin. All 325 chromosome number counts from 295 locations for all taxa in Solidago sect. Erectae (except subsect. Humiles), S. sect. Squarrosae, S. sect. Villosicarpae and S. sect. Brintonia were used to create cytogeography maps for these taxa (Figures 1-9).
The sizes of the ranges of species vary greatly in the genus Solidago as does the number of known populations within each range. Range size and frequency of occurrence within that range varies from very narrow and very rare, e.g., S. porteri (known only at the hexaploid level 2n = 54) and S. villosicarpa (known only at the diploid level 2n = 18), to relatively widely distributed and common, e.g., S. hispida (known only at the diploid level 2n = 18) and S. speciosa (known at both the diploid and tetraploids levels). The reasons for these differences are not known, although in some cases rare species appear to be found growing in rare habitats with distinct soil characteristics associated with particular communities of dominant plants, e.g., S. villosicarpa (LeBlond 2000 [43]). Semple and Cook [3] included comments on habitats of all species discussed below.