From Ornamental Beauty to Economic and Horticultural Significance: Species Diversity and Ethnobotany of Bignoniaceae in Maha Sarakham Province, Thailand

Abstract

The Bignoniaceae family encompasses numerous species of ecological, medicinal, and cultural significance, yet its ethnobotanical value remains underexplored in many regions of Thailand. This study investigates the diversity, phenology, cultural relevance, and traditional uses of Bignoniaceae species in Maha Sarakham Province, Northeastern Thailand. Through semi-structured interviews with 260 local informants across 13 districts—alongside field observations and herbarium voucher collections—we documented 27 species across 21 genera. These integrated methods enabled the identification of key culturally significant species and provided insights into their traditional uses. Phenological data revealed clear seasonal patterns in flowering and fruiting, aligned with the regional climatic cycle. Quantitative ethnobotanical indices—including Species Use Value (SUV), Genera Use Value (GUV), Relative Frequency of Citation (RFC), Cultural Importance Index (CI), and Cultural Food Significance Index (CFSI)—were employed to evaluate species significance. Results indicate that species such as Dolichandrone serrulata, D. spathacea, and Oroxylum indicum hold high cultural and practical value, particularly in traditional medicine, spiritual practices, and local landscaping. These findings underscore the critical role of Bignoniaceae in sustaining biocultural diversity and emphasize the urgency of preserving traditional botanical knowledge amid environmental and socio-economic change. Moreover, the insights contribute to broader efforts in cultural heritage preservation and biodiversity conservation across tropical and subtropical regions.

1. Introduction

Ethnobotany, the study of the relationship between people and plants, has become an essential field of research in understanding the complex interactions between humans and their natural environment [1]. Plants are vital to human societies, serving as sources of food, medicine, construction materials, and cultural practices [2]. One such group of plants, the Bignoniaceae family, has garnered interest for its diverse uses and its presence in various aspects of life in tropical and subtropical regions [3]. In Thailand, particularly in the northeastern province of Maha Sarakham, members of the Bignoniaceae family play an integral role in the daily lives of local communities [4]. The province, situated in the heart of the Isan region, is known for its rich cultural heritage, where traditional knowledge of plant species is passed down through generations. Maha Sarakham has a tropical monsoon climate with distinct seasons and generally lower rainfall due to its location in a rain shadow zone. These seasonal changes affect plant growth and availability, influencing their traditional uses [5].

Despite the ecological and cultural relevance of Bignoniaceae in the region, there is a significant lack of focused ethnobotanical research on this plant family in Thailand. The Bignoniaceae family is a diverse group of plants that includes approximately 80 genera and over 800 species, found mainly in tropical and subtropical regions of the world [6]. In Thailand, species of the Bignoniaceae family are abundant, and they are commonly used for ornamental, medicinal, food, and practical purposes [7]. In Maha Sarakham Province, many species of this family are cultivated in home gardens, temples, schools, and other public spaces for various uses [8]. The unique characteristics of these plants—such as vibrant flowers, large fruits, and strong timber—make them valuable both for their aesthetic and functional qualities [9]. Understanding the traditional knowledge surrounding these plants provides insight into the role they play in the daily lives of local communities, especially in rural settings where indigenous practices and traditional ecological knowledge remain strong [10].

However, there exists a notable gap in ethnobotanical research specifically related to the Bignoniaceae family in Thailand. While studies have been conducted on the ethnobotany of various plant families in Southeast Asia [11], little attention has been given to the specific uses of Bignoniaceae species in Thai communities, especially in the northeastern regions like Maha Sarakham. This research gap is critical, as it threatens the preservation of rich plant knowledge associated with cultural identity and sustainable practices. This gap in research means that the valuable traditional knowledge regarding these plants, including their uses in medicine, food, rituals, and other cultural practices, remains poorly documented. As a result, much of the cultural heritage tied to these plants is at risk of being lost, especially as modern development and urbanization continue to encroach upon rural areas [12]. Thus, it is critical to document the ethnobotanical significance of these species to preserve both the plant knowledge and the cultural practices associated with them [13].

To address this need, the present study investigates the ethnobotanical significance of the Bignoniaceae family in Maha Sarakham Province. The objectives are to document the traditional uses of these species, analyze their cultural importance, and explore the ways in which local communities continue to utilize them in daily life. By filling this knowledge gap, the research contributes baseline data essential for both cultural preservation and future conservation planning. This research seeks to contribute meaningful data to the field of ethnobotany and highlight the need for conservation strategies that respect and integrate traditional knowledge.

2. Materials and Methods

2.1. Study Area

This study was conducted throughout Maha Sarakham Province (Figure 1), located in northeastern Thailand, a region noted for its rich biodiversity and cultural heritage. The province was selected due to its notable diversity of plant species, particularly those in the Bignoniaceae family, which are culturally and economically significant to local communities. Maha Sarakham experiences a tropical monsoon climate characterized by three distinct seasons: hot, rainy, and cool. Positioned within a rain shadow region, the province generally receives less annual precipitation compared to neighboring areas, although heavy rains and occasional flooding can occur during the rainy season due to tropical weather systems. Temperatures fluctuate significantly throughout the year, with hot conditions dominating the dry season and cooler temperatures prevailing during the cool season. These seasonal climatic variations strongly influence the phenology of local vegetation, including the Bignoniaceae species studied here, affecting their growth, flowering, and fruiting cycles. The province’s vegetation zones encompass a mosaic of natural forests, agricultural landscapes, and disturbed habitats, reflecting both ecological diversity and human land use. Our research followed a broad, province-wide survey approach rather than focusing on specific fixed plots. Fieldwork was carried out across a wide range of accessible areas, including natural forests, agricultural lands, roadside environments, local markets, community centers, and plant nurseries. These areas represent the variety of habitats where Bignoniaceae species are encountered and utilized. The selection of these sites was guided by ethnobotanical relevance, community interactions, and the presence of plant species from the target family. Data collection included direct observations, semi-structured interviews with local people, and photographic documentation. Local markets and community spaces were particularly valuable for understanding the economic and cultural uses of Bignoniaceae species. Given the flexible and exploratory nature of the study design, a fixed sampling grid or site-specific map was not employed, as our goal was to capture a comprehensive picture of species use and distribution across the province [4,5,8].

2.2. Data Collection

Data collection for this study was conducted over a one-year period, from April 2024 to March 2025, using a mixed-methods approach to gather both qualitative and quantitative data on the diversity, economic values, and ethnobotanical uses of Bignoniaceae species in Maha Sarakham Province. Field surveys were carried out across diverse ecological and cultural sites, including forests, community centers, agricultural areas, and 17 local markets (14 vegetable markets and 3 plant markets), representing key locations where Bignoniaceae species are cultivated, traded, or utilized.

Semi-structured interviews were conducted once with each of the 260 informants, comprising plant vendors, sellers, and buyers. The interviews focused on documenting traditional knowledge, local plant names, plant parts used, preparation methods, uses, and community preferences. Economic data—including prices, sales volumes, and quantities sold—were systematically collected every four months to analyze market dynamics and supply–demand trends.

Botanical surveys were conducted simultaneously to identify and verify species, with taxonomic identification confirmed through detailed specimen comparison and consultation with local botanists and taxonomic experts.

All collected data were compiled into a structured database to enable comprehensive analyses of biodiversity, market activity, and cultural significance of Bignoniaceae species within the province.

2.3. Taxonomic Identification

Species identification was carried out through detailed comparison of collected specimens with original species descriptions and authoritative reference materials available from Plants of the World Online (POWO) [14] and Flora of Thailand Volume 5, Part 1 [15]. To ensure accuracy and up-to-date classification, a comprehensive review of relevant taxonomic literature was performed using major scientific databases, including Scopus, Web of Science, and Google Scholar. Additionally, digital images and resources from the Kew Herbarium and the Kew Science website were consulted for morphological comparison and confirmation of species identity.

2.4. Plant Specimen Preservation

Plant specimens collected during field surveys were preserved using standard herbarium techniques. Fresh specimens were initially pressed between sheets of newspaper using a plant press to maintain their structural integrity and prevent decay. These pressed specimens were then air-dried thoroughly in a well-ventilated area. In cases where immediate drying was not possible, samples were temporarily preserved in 70% ethanol to prevent decomposition. After drying, all specimens were carefully mounted on herbarium sheets and labeled with relevant collection data. The preserved specimens were subsequently deposited in the Vascular Plant Herbarium, Mahasarakham University (VMSU), Thailand, for long-term storage and reference.

2.5. Phenology Study

This research examines the phenological patterns of Bignoniaceae in Maha Sarakham Province, with particular attention to their flowering and fruiting cycles. Months were represented numerically, ranging from 1 (January) to 12 (December). Gaining insight into these reproductive phases is essential for assessing both the reproductive success and the economic significance of the species [16].

2.6. Utilization Study

Data on the use of Bignoniaceae plants in Maha Sarakham Province were obtained through interviews with 260 local residents, consisting of an equal number of male and female participants (130 each) from various districts. All participants were permanent residents and homeowners in the province; individuals living in rental accommodations were excluded. Informed consent was obtained from all participants after clearly explaining the objectives of the study to ensure voluntary and informed participation. The interviews focused on gathering information related to local plant names, plant parts used, methods of preparation, and the purposes of use. As no personal or identifying information was collected, formal ethical approval was not required for this study.

2.7. Data Analysis

2.7.1. Species Use Value (SUV)

The Species Use Value (SUV) is a metric that reflects the local significance of a Bignoniaceae species as perceived by residents of Maha Sarakham Province. This value is calculated following the methodologies of Hoffman and Gallaher [17] and is represented by the equation:

$$\mathrm{SUV}={\displaystyle \frac{\sum {\mathrm{UV}}_{\mathrm{is}}}{{\mathrm{n}}_{\mathrm{i}}}}$$

(1)

where UV_is denotes the use value reported by an individual informant for a specific species. It is computed by dividing the total number of use citations for that species (across all use categories, weighted equally) by the number of times the informant referred to any use of that species during the study period. n_i is the total number of informants interviewed.

The overall SUV for a species is obtained by summing the individual use values (UV_is) across all informants and dividing by the total number of informants, providing a standardized measure of the species’ ethnobotanical importance.

2.7.2. Genera Use Value (GUV)

The Genera Use Value (GUV) represents the cultural importance of a plant genus used in ritual practices by the people of Maha Sarakham Province. This value is calculated using a modified method [18] and is defined by the following Formula (2):

$$\mathrm{GUV}={\displaystyle \frac{\sum \mathrm{SUV}}{{\mathrm{N}}_{\mathrm{s}}}}$$

(2)

In this equation, ∑SUV refers to the total use values of all species within the genus, and N_s is the number of species included in the calculation. The GUV is derived by dividing the sum of species use values by the total number of species in the genus.

2.7.3. Relative Frequency of Citation (RFC)

The Relative Frequency of Citation (RFC) was utilized to assess how frequently specific plant species were used. This value is calculated using a modified method [19] and is defined by the following Formula (3):

RFC = FC/N

(3)

where RFC stands for the Relative Frequency of Citation, FC represents the number of informants who reported a specific Bignoniaceae plant, and N refers to the total number of informants surveyed.

RFC values range from 0 to 1, with higher values reflecting a plant’s greater cultural and dietary significance in the region. This measure was used to rank Bignoniaceae species according to their relative importance, offering a quantitative analysis of their utilization.

2.7.4. Cultural Importance Index (CI)

The Cultural Importance Index (CI) was calculated to determine the significance of each species based on its reported uses by informants. The Cultural Importance Index (CI) [19] was calculated to determine the significance of each species based on its reported uses by informants. The CI was derived using the Formula (4):

$${\mathrm{CI}}_{\mathrm{s}}={\displaystyle \sum }_{\mathrm{u}={\mathrm{u}}_1}^{{\mathrm{u}}_{\mathrm{NC}}}{\displaystyle \sum }_{\mathrm{i}={\mathrm{i}}_1}^{{\mathrm{i}}_{\mathrm{N}}}{\displaystyle \frac{{\mathrm{UR}}_{\mathrm{ui}}}{\mathrm{N}}}$$

(4)

Here, UR_ui represents the number of use reports for a particular species by an individual informant, N is the total number of informants, and NC is the total number of use categories.

2.7.5. Cultural Food Significance Index (CFSI)

In this research, we utilized the Cultural Food Significance Index (CFSI) to evaluate the cultural importance of Bignoniaceae species used for both food and medicinal purposes. First proposed by Pieroni in 2001 [20], the CFSI integrates seven distinct indicators of food significance into a single comprehensive metric, calculated as follows:

CFSI = QI × AI × FUI × PUI × MFFI × TSAI × FMRI × 10⁻²

(5)

The indices used include the Frequency of Quotation Index (QI), Availability Index (AI), Frequency of Utilization Index (FUI), Parts Used Index (PUI), Multifunctional Food Use Index (MFFI), Taste Score Appreciation Index (TSAI), and Food-Medicinal Role Index (FMRI).

2.7.6. Informant Consensus Factor (F_ic)

To assess the variability in the use of medicinal plants, the Informant Consensus Factor (F_ic) was calculated using the following formula [21]:

$${\mathrm{F}}_{\mathrm{ic}}={\displaystyle \frac{{\mathrm{n}}_{\mathrm{ur}}-{\mathrm{n}}_{\mathrm{t}}}{{\mathrm{n}}_{\mathrm{ur}}-1}}$$

(6)

In this formula, n_ur represents the total number of use reports within a particular use category, and n_t denotes the number of taxa used in that category. The F_ic value indicates the degree of agreement among informants about the medicinal use of plants, with higher values suggesting a stronger consensus on the use of specific plant species for therapeutic purposes.

2.7.7. Fidelity Level (%FL)

The fidelity level (FL) represents the percentage of informants who linked a particular plant species to the treatment of a specific ailment in the study area [22]. It is determined using the following formula:

$$\mathrm{FL}={\displaystyle \frac{{\mathrm{I}}_{\mathrm{p}}}{{\mathrm{I}}_{\mathrm{u}}}}\times 100$$

(7)

where I_p refers to the number of informants who specifically associated the plant with a particular health issue, and I_u indicates the total number of informants who recognized the plant’s medicinal use for any health condition.

2.7.8. Jaccard’s Similarity Index (JI)

To assess species diversity similarity across all index, the Jaccard’s Similarity Index (JI) was employed. This index is a widely recognized method for measuring the similarity between two datasets. The Jaccard Similarity Index (JI) is calculated using the following formula:

JI = a/(a + b + c)

(8)

In the formula, the following are defined:

a = The number of species common to both districts.

b = The species unique to the first district.

c = The species exclusive to the second district.

Additionally, the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) was used to explore the similarities in species diversity across districts. The Jaccard Similarity Index was the foundation for creating a similarity matrix, which was then processed through the UPGMA algorithm and using Past4 software (version 4.15) to make a heatmap.

2.8. The Economic Value

The economic value assessment of Bignoniaceae focused on local market interactions between sellers and buyers of these plants in Maha Sarakham Province. Quantitative data were collected from both groups, targeting species actively traded in local markets. Price and sales data were systematically recorded every four months over one year (April 2024 to March 2025).

For ornamental species sold as whole plants, total yearly income was calculated using a method adapted from Saensouk et al. [23], as follows:

Annual Economic Value = Np × Pp

(9)

In the formula for determining the annual economic value of ornamental plant species, Np refers to the number of pots sold per year, while Pp represents the average price per pot. These two variables are multiplied to estimate the total economic value generated from the sale of ornamental plants throughout the year.

3. Results

3.1. Diversity of Bignoniaceae in Maha Sarakham Province

The study found 27 species of Bignoniaceae across 21 genera in Maha Sarakham Province (

Table 1. Diversity of Bignoniaceae species in Maha Sarakham Province, along with their vernacular name, distribution status in Thailand, Conservation status (IUCN), ecology, utilization, used parts, phenology, SUV, RFC, CI, voucher no.

No.	Scientific Name	Vernacular Name	Distribution Status in Thailand	Conservation Status (IUCN) [24]	Ecology	Utilization	Used Parts	Phenology		SUV	RFC	CI	Voucher No.
								Flowering	Fruiting
1.	Bignonia magnifica W.Bull	Muang Manirat	Introduced	NE	Cultivated	cc, on	wp	12-2	2-3	0.146	0.135	0.154	TB&TJ001
2.	Campsis grandiflora (Thunb.) K.Schum.	Mathurada	Introduced	NE	Cultivated	cc, on	wp	1-12	Not seen	0.142	0.138	0.162	TB&TJ002
3.	Campsis radicans (L.) Bureau	Rung Arun	Introduced	NE	Cultivated	cc, on	wp	1-12	Not seen	0.104	0.115	0.142	TB&TJ003
4.	Crescentia alata Kunth	Tin Pet Farang	Introduced	NE	Cultivated	cc, md, on	lv, wp	1-12	11-2	0.154	0.150	0.169	TB&TJ004
5.	Crescentia cujete L.	Nam Tao Ton	Introduced	LC	Cultivated	cc, md	ba, hw, lv, wp	1-12	11-2	0.077	0.096	0.081	TB&TJ005
6.	Dolichandrone serrulata (Wall. ex DC.) Seem.	Khae Na	Native	LC	Cultivated/Wild	cc, dy, fi, fo, md, on	ba, hw, if, lv, ro, sd, st, wp	3-6	4-7	0.381	0.365	0.400	TB&TJ006
7.	Dolichandrone spathacea (L.f.) K.Schum.	Khae Nam	Native	LC	Cultivated	cc, fi, fo, md, on	ba, hw, if, lv, ro, sd, st, wp	3-6	4-7	0.365	0.362	0.388	TB&TJ007
8.	Fernandoa adenophylla (Wall. ex G.Don) Steenis	Khae Hang Khang	Native	LC	Cultivated/Wild	cc, fi, fo, md, on	ba, if, lv, sd, st, wp	7-11	11-12	0.254	0.250	0.281	TB&TJ008
9.	Handroanthus chrysanthus (Jacq.) S.O.Grose	Lueang India	Introduced	VU	Cultivated	cc, on	wp	3-4	4-5	0.127	0.123	0.154	TB&TJ009
10.	Jacaranda mimosifolia D.Don	Si Trang	Introduced	VU	Cultivated	cc, on	wp	1-3	4-5	0.123	0.123	0.173	TB&TJ010
11.	Kigelia africana (Lam.) Benth.	Saikrok Aefrika	Introduced	LC	Cultivated	cc, on	wp	1-3	1-3	0.085	0.077	0.092	TB&TJ011
12.	Mansoa alliacea (Lam.) A.H.Gentry	Krathiam Thao	Introduced	NE	Cultivated	cc, on	wp	11-2	Not seen	0.112	0.108	0.127	TB&TJ012
13.	Markhamia stipulata (Wall.) Seem.	Khae Huamu	Native	LC	Cultivated/Wild	cc, fi	st, wp	3-5	5-6	0.073	0.062	0.081	TB&TJ013
14.	Mayodendron igneum (Kurz) Kurz	Ka Sa Long Kham	Native	LC	Cultivated/Wild	cc, on	wp	1-4	5-7	0.123	0.115	0.138	TB&TJ014
15.	Millingtonia hortensis L.f.	Pip	Native	LC	Cultivated/Wild	cc, dy, md, on, rp	ba, if, ro, wp	9-4	11-5	0.350	0.346	0.412	TB&TJ015
16.	Oroxylum indicum (L.) Kurz	Phe Ka	Native	LC	Cultivated/Wild	cc, dy, fi, fo, md	ba, ft, if, lv, st, wp	3-7	7-12	0.358	0.350	0.415	TB&TJ016
17.	Podranea ricasoliana (Tanfani) Sprague	Haep Pi Net, Chomphu Hawai	Introduced	NE	Cultivated	cc, on	wp	1-12	Not seen	0.154	0.142	0.158	TB&TJ017
18.	Pyrostegia venusta (Ker Gawl.) Miers	Phuangsaet	Introduced	NE	Cultivated	cc, on	wp	12-3	Not seen	0.177	0.181	0.204	TB&TJ018
19.	Radermachera yunnanensis C.Y.Wu & W.C.Yin	Pip Yu Nan	Introduced	LC	Cultivated	cc, on	wp	9-11	9-11	0.142	0.135	0.154	TB&TJ019
20.	Spathodea campanulata P.Beauv.	Khaesaet	Introduced	LC	Cultivated	cc, fo, md, on	ba, if, wp	10-2	11-2	0.212	0.192	0.258	TB&TJ020
21.	Stereospermum neuranthum Kurz	Khae Sai	Native	LC	Cultivated/Wild	cc, fi, fo, hc	if, st, wp	3-5	4-6	0.204	0.192	0.223	TB&TJ021
22.	Tabebuia aurea (Silva Manso) Benth. & Hook.f. ex S.Moore	Lueang Pridi Ya Thon	Introduced	NE	Cultivated	cc, on	wp	2-3	2-3	0.188	0.185	0.196	TB&TJ022
23.	Tabebuia pallida (Lindl.) Miers	Trae Chomphu	Introduced	LC	Cultivated	cc, on	wp	3-10	6-11	0.127	0.115	0.150	TB&TJ023
24.	Tabebuia rosea (Bertol.) DC.	Chomphu PhanThip	Introduced	NE	Cultivated	cc, fi, hc, md, on	lv, st, wp	2-4	Not seen	0.235	0.250	0.258	TB&TJ024
25.	Tecoma stans (L.) Juss. ex Kunth cv. ‘Thong Urai Lueang’	Thong Urai Lueang	Introduced	LC	Cultivated	cc, md, on, rp	ba, if, wp	1-12	1-12	0.342	0.308	0.369	TB&TJ025
26.	Tecoma stans (L.) Juss. ex Kunth cv. ‘Thong Urai Micky Mouse’	Thong Urai Micky Mouse	Introduced	LC	Cultivated	cc, on	wp	1-12	1-12	0.181	0.158	0.192	TB&TJ026
27.	Tecomaria capensis ‘Aurea’	Phuangsaet Ton	Introduced	LC	Cultivated	cc, on	wp	12-3	Not seen	0.177	0.154	0.215	TB&TJ027

Abbreviations: Conservation status: least concern (LC), not evaluated (NE), vulnerable (VU). Utilization: commercial cultivation (cc), Dyes (dy), firewood (fi), food (fo), handicrafts (hc), ornamental (on), medicines (md), ritual activities (rp). Used parts: bark (ba), fruit (ft), heart-wood (hw), inflorescence (if), leave (lv), root (ro), seed (sd), stem (st), whole plant (wp).

, Figure 2 and Figure 3). Most genera are represented by a single species, including Bignonia, Fernandoa, Handroanthus, Jacaranda, Kigelia, Mansoa, Markhamia, Mayodendron, Millingtonia, Oroxylum, Podranea, Pyrostegia, Radermachera, Spathodea, Stereospermum, and Tecomaria. A few genera have multiple species, with Tabebuia being the most diverse (3 species), followed by Campsis, Crescentia, Dolichandrone, and Tecoma (each with 2 species). This pattern shows that while species diversity is spread across many genera, a small number of genera contain the majority of species.

3.2. Phenology of Bignoniaceae in Maha Sarakham Province

Flowering and fruiting of Bignoniaceae species in Maha Sarakham Province showed clear seasonal patterns (Figure 4). Flowering occurred year-round, peaking in March (22 species) and reaching its lowest in August (9 species). Fruiting followed a similar but less pronounced trend, with peaks in May and November (10 species each) and a low in August (4 species). Flowering was consistently more frequent than fruiting, indicating a reproductive strategy focused on the dry-to-early rainy season for flowering, with fruiting spread more variably throughout the year.

3.3. Species Use Value (SUV) of Bignoniaceae in Maha Sarakham Province

A detailed list of Bignoniaceae species and their corresponding Species Use Values (SUV) is presented in Table 1. These values indicate the extent to which each species is utilized across various domains in Maha Sarakham Province, including commercial cultivation, ornamental planting, traditional medicine, firewood, food, handicrafts, dye production, and ritual practices.

To facilitate interpretation, SUVs were grouped into three categories: high (SUV ≥ 0.30), medium (SUV 0.15–0.29), and low (SUV < 0.15). These categories were defined based on the range and distribution of SUV scores in this study and are used here as a heuristic framework to represent varying degrees of cultural and practical importance among species.

The high-use value category (SUV ≥ 0.30) comprises species that are widely utilized within local communities and serve multiple purposes. Among these, Dolichandrone serrulata (SUV = 0.381), D. spathacea (SUV = 0.365), and Oroxylum indicum (SUV = 0.358) are especially valued for their applications in traditional medicine, ritual practices, and, in some cases, ornamental planting. Millingtonia hortensis (SUV = 0.350) is commonly grown for ornamental and ritual purposes, and it is also popular in commercial cultivation due to its fragrant flowers. Tecoma stans cv. ‘Thong Urai Lueang’ (SUV = 0.342) is another high-SUV species, primarily cultivated as an ornamental plant, with additional value in medicinal uses.

The medium-use value category (SUV 0.15–0.29) includes species that are moderately utilized in the region. Fernandoa adenophylla (SUV = 0.254), Tabebuia rosea (SUV = 0.235), and Spathodea campanulata (SUV = 0.212) are mostly grown for ornamental purposes, though they are occasionally referenced in medicinal practices. Stereospermum neuranthum (SUV = 0.204) and Tabebuia aurea (SUV = 0.188) are sometimes used as firewood and also serve decorative functions. Other species in this category, such as Pyrostegia venusta (SUV = 0.177) and Tecomaria capensis ‘Aurea’ (SUV = 0.177), are mainly appreciated for their aesthetic appeal. Crescentia alata and Podranea ricasoliana (SUV = 0.154 each) are likewise cultivated primarily for ornamental purposes.

The low-use value category (SUV < 0.15) includes species with limited use or more restricted cultural relevance. Markhamia stipulata (SUV = 0.073), Crescentia cujete (SUV = 0.077), and Kigelia africana (SUV = 0.085) are occasionally used for firewood or ornamental purposes. Campsis radicans (SUV = 0.104), Mansoa alliacea (SUV = 0.112), and Jacaranda mimosifolia (SUV = 0.123) are primarily grown as ornamentals, with minor additional uses. Similarly, Tabebuia pallida and Handroanthus chrysanthus (SUV = 0.127 each), along with Mayodendron igneum (SUV = 0.123), are cultivated for their aesthetic value. Bignonia magnifica (SUV = 0.146), Campsis grandiflora, and Radermachera yunnanensis (SUV = 0.142 each) are also mainly valued for ornamental planting.

3.4. Genera Use Value (GUV) of Bignoniaceae in Maha Sarakham Province

Table 2. Average Genera Use Values (GUVs) of Bignoniaceae Species in Maha Sarakham Province.

Genus	Genera Use Value (GUV)
Dolichandrone	0.373
Oroxylum	0.358
Millingtonia	0.350
Tecoma	0.262
Fernandoa	0.254
Spathodea	0.212
Stereospermum	0.204
Tabebuia	0.183
Pyrostegia	0.177
Tecomaria	0.177
Podranea	0.154
Bignonia	0.146
Radermachera	0.142
Handroanthus	0.127
Campsis	0.123
Jacaranda	0.123
Mayodendron	0.123
Crescentia	0.115
Mansoa	0.112
Kigelia	0.085
Markhamia	0.073

presents the Genera Use Values (GUVs) of Bignoniaceae recorded in Maha Sarakham Province. These values represent the average use of all species within each genus, offering insight into the overall significance of each genus based on local knowledge and utilization.

To facilitate interpretation, GUVs were categorized into three groups based on the range of values observed in this study: high (≥0.30), medium (0.15–0.29), and low (<0.15). This classification was used as an interpretive tool to help differentiate the relative cultural and practical importance of each genus.

The high-use value genera (GUV ≥ 0.30) include Dolichandrone (GUV = 0.373), Millingtonia (GUV = 0.350), and Oroxylum (GUV = 0.358). These genera are among the most valued in the province, with species widely used for medicinal, ornamental, and ritual purposes, and often involved in commercial cultivation. Their consistent presence across various uses underscores their ecological and cultural relevance in the region.

Genera with a medium-use value (GUV 0.15–0.29) include Tecoma (GUV = 0.262), Fernandoa (GUV = 0.254), Spathodea (GUV = 0.212), Stereospermum (GUV = 0.204), Tabebuia (GUV = 0.183), Pyrostegia and Tecomaria (GUV = 0.177 each), and Podranea (GUV = 0.154). These genera include species used for ornamental planting, medicinal applications, and occasionally for firewood or ritual purposes. Though not as dominant as the high-GUV group, they still hold moderate significance in local contexts.

Genera with low-use value (GUV < 0.15) include Bignonia (GUV = 0.146), Radermachera (GUV = 0.142), Campsis and Mayodendron (GUV = 0.123 each), Jacaranda (GUV = 0.123), Handroanthus (GUV = 0.127), Mansoa (GUV = 0.112), Crescentia (GUV = 0.115), Kigelia (GUV = 0.085), and Markhamia (GUV = 0.073). These genera are primarily used for ornamentals, with limited or specialized use in other domains such as rituals or firewood. While their aesthetic value is acknowledged, their broader utility remains relatively low compared to more frequently utilized genera.

3.5. Relative Frequency of Citation (RFC) of Bignoniaceae in Maha Sarakham Province

A comparative assessment between the Relative Frequency of Citation (RFC) and Species Use Value (SUV) shows a tendency to move in the same direction, indicating that species frequently cited by informants tend to have higher utility (

Table 3. Comparison between Relative Frequency of Citation (RFC) and Species Use Value (SUV) of Bignoniaceae species used in Maha Sarakham Province.

Scientific Name	RFC	SUV
Dolichandrone serrulata (Wall. ex DC.) Seem. (Khae Na)	0.365	0.381
Dolichandrone spathacea (L.f.) K.Schum.	0.362	0.365
Oroxylum indicum (L.) Kurz	0.350	0.358
Millingtonia hortensis L.f.	0.346	0.350
Tecoma stans (L.) Juss. ex Kunth	0.308	0.342
Fernandoa adenophylla (Wall. ex G.Don) Steenis	0.250	0.254
Tabebuia rosea (Bertol.) DC.	0.250	0.235
Spathodea campanulata P.Beauv.	0.192	0.212
Stereospermum neuranthum Kurz	0.192	0.204
Tabebuia aurea (Silva Manso) Benth. & Hook.f. ex S.Moore	0.185	0.188
Pyrostegia venusta (Ker Gawl.) Miers	0.181	0.177
Tecoma stans (L.) Juss. ex Kunth	0.158	0.181
Tecomaria capensis ‘Aurea’	0.154	0.177
Crescentia alata Kunth	0.150	0.154
Podranea ricasoliana (Tanfani) Sprague	0.142	0.154
Campsis grandiflora (Thunb.) K.Schum.	0.138	0.142
Bignonia magnifica W.Bull	0.135	0.146
Radermachera yunnanensis C.Y.Wu & W.C.Yin	0.135	0.142
Handroanthus chrysanthus (Jacq.) S.O.Grose	0.123	0.127
Jacaranda mimosifolia D.Don	0.123	0.123
Campsis radicans (L.) Bureau	0.115	0.104
Mayodendron igneum (Kurz) Kurz	0.115	0.123
Tabebuia pallida (Lindl.) Miers	0.115	0.127
Mansoa alliacea (Lam.) A.H.Gentry	0.108	0.112
Crescentia cujete L.	0.096	0.077
Kigelia africana (Lam.) Benth.	0.077	0.085
Markhamia stipulata (Wall.) Seem.	0.062	0.073

). However, several discrepancies between RFC and SUVs among species suggest that citation frequency does not always equate to greater diversity of use.

For instance, Dolichandrone serrulata, D. spathacea, and Oroxylum indicum not only have the highest RFC values (0.365, 0.362, and 0.350, respectively) but also rank highest in SUV (0.381, 0.365, and 0.358). This reflects both widespread knowledge and a broad range of uses within the local communities.

Conversely, certain species such as Tecoma stans (RFC = 0.308; SUV = 0.342) and Tecomaria capensis ‘Aurea’ (RFC = 0.154; SUV = 0.177) show higher use values relative to their citation frequencies. This suggests that while these species are known to fewer people, they are highly valued by those who do use them, possibly due to their specialized or multifunctional roles.

In contrast, some species with relatively moderate RFCs exhibit lower SUVs, such as Tabebuia rosea (RFC = 0.250; SUV = 0.235), indicating that although they are widely known, they may serve limited or singular uses.

The lowest RFC and SUVs were observed in species such as Markhamia stipulata (RFC = 0.062; SUV = 0.073) and Kigelia africana (RFC = 0.077; SUV = 0.085), highlighting their limited ethnobotanical recognition and application in the study area.

3.6. Cultural Significance Value (CI) of Bignoniaceae in Maha Sarakham Province

The Cultural Importance (CI) values of Bignoniaceae species in Maha Sarakham Province vary considerably, reflecting different levels of cultural significance (Table 1). Oroxylum indicum (0.415) holds the highest CI value, followed closely by Millingtonia hortensis (0.412) and Dolichandrone serrulata (0.400), highlighting their strong cultural relevance.

Other species such as Dolichandrone spathacea (0.388) and Tecoma stans cv. ‘Thong Urai Lueang’ (0.369) also demonstrate notable cultural importance. Fernandoa adenophylla (0.281) and Spathodea campanulata (0.258) exhibit moderate CI values, indicating a consistent cultural presence.

Species like Tabebuia rosea (0.258), Tecomaria capensis ‘Aurea’ (0.215), and Stereospermum neuranthum (0.223) show moderate to low levels of cultural significance. Meanwhile, species such as Pyrostegia venusta (0.204) and Tabebuia aurea (0.196) have a lesser but still relevant cultural role.

Several species, including Tecoma stans cv. ‘Thong Urai Micky Mouse’ (0.192), Jacaranda mimosifolia (0.173), and Crescentia alata (0.169), hold relatively low CI values, reflecting their more limited cultural use. Campsis grandiflora (0.162), Bignonia magnifica (0.154), and Handroanthus chrysanthus (0.154) also show lower CI values, indicating a relatively minor cultural importance.

Finally, species like Kigelia africana (0.092), Crescentia cujete (0.081), and Markhamia stipulata (0.081) have the lowest CI values, suggesting their minimal yet still present role in the region’s cultural practices. These varying CI values reflect the diversity in cultural importance among Bignoniaceae species in Maha Sarakham Province.

The Cultural Importance (CI) values for the utilization of Bignoniaceae species in Maha Sarakham Province reveal varying levels of significance across different categories (

Table 4. Cultural Importance Index (CI) for each category of use.

Utilization	CI
Ornamentals	2.34
Commercial cultivation	1.39
Food	0.70
Medicines	0.53
Firewood	0.41
Ritual uses	0.15
Dyes	0.13
Handicrafts	0.08

). Ornamentals have the highest CI value (2.34), indicating their major role in the cultural and aesthetic landscape of the region.

Commercial cultivation follows with a CI value of 1.39, highlighting the economic importance of these species. The Food category also has a notable CI value of 0.70, showing that Bignoniaceae species are utilized as a food source within the community.

Uses such as medicines (0.53) and firewood (0.41) hold moderate CI values, indicating a practical role in local life. On the other hand, dyes (0.13) and ritual uses (0.15) have relatively lower CI values, suggesting their limited but still recognized cultural importance. Handicrafts show the lowest CI value (0.08), reflecting a more minimal involvement in cultural practices.

3.7. Cultural Food Significance Index (CFSI) of Bignoniaceae in Maha Sarakham Province

A total of 11 species from the Bignoniaceae family were evaluated for their cultural food significance in Maha Sarakham Province using the Cultural Food Significance Index (CFSI) (

Table 5. Cultural Food Significance Index (CFSI) of Bignoniaceae used as food and medicine in Maha Sarakham Province.

Scientific Name	QI	AI	FUI	PUI	MFFI	TSAI	FMRI	CFSI
Dolichandrone serrulata (Wall. ex DC.) Seem.	35	4	4	5.75	1.0	9.0	3	869.400
Dolichandrone spathacea (L.f.) K.Schum.	36	3	4	5.00	1.0	7.5	3	486.000
Oroxylum indicum (L.) Kurz	39	4	4	0.75	1.0	10.0	3	140.400
Millingtonia hortensis L.f.	19	4	2	2.25	1.0	7.5	5	128.250
Fernandoa adenophylla (Wall. ex G.Don) Steenis	27	3	2	2.75	1.0	6.5	3	86.873
Tecoma stans (L.) Juss. ex Kunth	22	4	3	1.75	0.5	9.0	2	41.580
Crescentia alata Kunth	8	3	2	2.25	1.0	5.5	4	23.760
Crescentia cujete L.	9	2	1	4.25	1.0	5.5	4	16.830
Tabebuia rosea (Bertol.) DC.	9	3	3	1.50	1.0	5.5	2	13.365
Spathodea campanulata P.Beauv.	22	2	1	0.75	1.0	7.5	2	4.950
Stereospermum neuranthum Kurz	24	2	1	0.75	1.0	6.5	1	2.340

Abbreviations: quotation index (QI), availability index (AI), frequency of utilization index (FUI), plant parts used index (PUI), multi-functional food use index (MFFI), taste score appreciation index (TSAI), food-medicinal role index (FMRI), cultural food significance index (CFSI).

). The CFSI values varied widely, reflecting differences in cultural familiarity, usage frequency, and food-medicinal roles of the species.

The species with the highest CFSI was Dolichandrone serrulata, with a value of 869.400. This exceptionally high score was driven by its frequent citation (QI = 35), high frequency of use (FUI = 4), diversity of plant parts used (PUI = 5.75), and high appreciation in taste (TSAI = 9.0). This suggests that D. serrulata holds both culinary and medicinal significance in the region.

Dolichandrone spathacea ranked second, with a CFSI of 486.000, followed by Oroxylum indicum (140.400), Millingtonia hortensis (128.250), and Fernandoa adenophylla (86.873). These species showed a combination of moderate to high availability, multifunctional uses, and taste appreciation, making them culturally valuable food-medicinal plants.

Species with lower CFSI values included Spathodea campanulata (4.950), Stereospermum neuranthum (2.340), and Tabebuia rosea (13.365), indicating limited food-related use despite their presence in the local flora.

Interestingly, Crescentia alata (23.760) and C. cujete (16.830), though less cited, still contributed to local food traditions due to their distinct roles and availability.

The heatmap analysis (Figure 5) revealed notable variation in CFSI component scores across species. Dolichandrone serrulata exhibited the highest cultural food significance, reflected by its top-ranking QI value, indicating frequent mention by informants. It also scored highly on AI and FUI, suggesting both wide availability and frequent consumption. Dolichandrone spathacea also demonstrated strong cultural relevance, particularly through high AI and TSAI scores, implying its common presence in the wild and favorable taste perception.

Conversely, species such as Spathodea campanulata and Stereospermum neuranthum consistently received low scores across all indices, suggesting limited cultural integration as food sources. Most other species displayed moderate values across the indices, indicating variable but generally lesser roles in local food traditions.

Notably, species with higher PUI and MFFI scores (e.g., Millingtonia hortensis and Oroxylum indicum) were those consumed using multiple plant parts and through versatile methods (e.g., raw or cooked as a main component), underlining their broader culinary utility. In contrast, species with low FMRI values were seldom associated with medicinal uses, potentially reflecting a narrower ethnobotanical relevance.

The integration of these ethnobotanical indices through the CFSI framework enabled the identification of species with both high cultural value and potential for further development as nutritionally and culturally significant food resources.

3.8. Utilization of Bignoniaceae in Maha Sarakham Province

The most prevalent use of the surveyed Bignoniaceae species in Maha Sarakham Province (Table 5) was for ornamental purposes, accounting for 23 species (44.23%), followed by traditional medicine (10 species, 19.23%), and both firewood and food (each 6 species, 11.54%). Fewer species were used for dyes (3 species, 5.77%), handicrafts (2 species, 3.85%), and rituals or ceremonial activities (2 species, 3.85%) (Figure 6).

3.8.1. Bignoniaceae Used as Dyes

The surveyed Bignoniaceae plants, namely Dolichandrone serrulata, Millingtonia hortensis, and Oroxylum indicum, were reported to be used as dyes in the region (Table 1). The bark of D. serrulata is commonly used to dye silk, imparting a brown tone. Similarly, the bark of M. hortensis is used to dye silk, giving it a yellow tone. Both the bark and leaves of O. indicum are used to dye silk and cotton, producing a greenish-yellow tone. The informants highlighted the cultural significance of these plants in dyeing, emphasizing their practical use and importance in the region (

Table 6. Bignoniaceae species in Maha Sarakham Province used as dyes.

Scientific Name	Used Parts	Color Extraction	Dyeing Process	Color Obtained from Dyeing
Dolichandrone serrulata (Wall. ex DC.) Seem.	Bark	Chopping or blending the bark of the tree into small pieces. Use a ratio of 5 kg of bark per 1 kg of silk thread. Boil the bark in 30 L of water for one hour. Once boiling is complete, strain the mixture through a muslin cloth to obtain the extracted dye solution, which will be used for the dyeing process.	Soaking the degummed silk threads in clean water. After soaking, wring them until they are damp but not dry. Place the damp silk threads into the extracted dye solution at room temperature and soak for 10 min. Remove the threads and set them aside. Then, heat the dye solution until it reaches a boil and add one tablespoon of alum to act as a mordant. Re-immerse the silk threads in the heated dye bath, turning and stirring them regularly to ensure even absorption of the color. Continue dyeing for approximately one hour. After dyeing, rinse the silk threads in warm water mixed with a small amount of dishwashing liquid. Follow this by rinsing the silk in clean water until no residue remains. Finally, wring the silk threads to remove excess water and hang them to dry in the shade.	Brown
Millingtonia hortensis L.f.	Bark	Finely chop or grind the dye material, then add enough water to cover it. Boil the mixture for 1–2 h using a ratio of 500 g of material per 100 g of silk thread. After boiling, strain the mixture to collect only the dye liquid, adjusting the volume to 3 L.	Soak the degummed silk threads in water until fully saturated, then wring them until just damp. Immerse the silk in the dye solution at room temperature for 10 min. Remove the silk and let it rest in a container. Then, heat the dye bath to a temperature of 90–95 °C and add 3 g of alum. Re-immerse the silk in the heated dye solution and continue dyeing for 1 h. After dyeing, allow the silk to cool, rinse thoroughly with clean water, and hang to dry in the shade.	Yellow
Oroxylum indicum (L.) Kurz	Bark and Leaves	Boil approximately 10 kg of tree bark and leaves in 30 L of water for about 2 h. After boiling, strain the mixture to collect only the dye liquid.	Soak the cotton threads in the warm dye liquid to allow the color to absorb into the fibers. Then, boil the dye liquid together with the cotton threads for about 2 h, turning the threads occasionally during the process. After boiling, remove the pot from the heat and add 1 tablespoon of alum. Let the cotton soak in this mixture for about 5 min. Finally, wring out the excess dye from the threads and dry them under direct sunlight.	Greenish-yellow

).

3.8.2. Bignoniaceae Used as Firewood

The surveyed Bignoniaceae species, including Dolichandrone serrulata, D. spathacea, Fernandoa adenophylla, Markhamia stipulata, Oroxylum indicum, and Stereospermum neuranthum, were reported to be used as firewood in the region (Table 1). These species serve as important fuel sources for the local community, playing a crucial role in meeting cooking and heating needs. The use of these plants emphasizes the practical application of readily available plant materials for daily energy requirements.

3.8.3. Bignoniaceae Used as Food

The surveyed Bignoniaceae species, including Dolichandrone serrulata, D. spathacea, Fernandoa adenophylla, Oroxylum indicum, Spathodea campanulata, and Stereospermum neuranthum, were reported to be used as food sources in the region (Table 1). These species provide valuable edible parts, such as fruits, flowers, and leaves, which are incorporated into various traditional dishes and local culinary practices. For example, the fruit and young leaves of O. indicum are commonly consumed for their nutritional value, while the edible flowers of Spathodea campanulata, D. serrulata, and D. spathacea are used in local cuisine. The use of these plants for food highlights their significance in local diets, contributing to both the nutritional and cultural practices of the community (

Table 7. Bignoniaceae species in Maha Sarakham Province used as food.

Scientific Name	Used Parts	Method of Use	Notes
Dolichandrone serrulata (Wall. ex DC.) Seem.	Inflorescence	Boiling	Eat as vegetable with chili paste, Papaya salad, or with other dishes
Dolichandrone spathacea (L.f.) K.Schum.	Inflorescence	Boiling	Eat as vegetable with chili paste or with other dishes
Fernandoa adenophylla (Wall. ex G.Don) Steenis	Inflorescence	Boiling	Eat as vegetable with chili paste or with other dishes
Oroxylum indicum (L.) Kurz	Inflorescence	Boiling	Eat as vegetable with chili paste or with other dishes
	Fruit	Grilled or eat fresh	Eat as vegetable with chili paste or with other dishes
	Young leaves	Eat fresh	Eat as vegetable with chili paste or with other dishes
Spathodea campanulata P.Beauv.	Inflorescence	Boiling	Eat as vegetable with chili paste or with other dishes
Stereospermum neuranthum Kurz	Inflorescence	Boiling	Eat as vegetable with chili paste or with other dishes

).

3.8.4. Bignoniaceae Used as Handicrafts

The survey found that Stereospermum neuranthum and Tabebuia rosea, both from the Bignoniaceae family, are used for handicrafts in the region (Table 1). These plants are valued for their materials, with the wood of S. neuranthum being used to make poles, floorboards, and house walls. Additionally, the trunk of T. rosea, in addition to being utilized as firewood, is also used as pulp to make paper. The use of these plants highlights their cultural significance in local handicrafts and underscores their contribution to the handicraft traditions of the region.

3.8.5. Bignoniaceae Used for Ornamental Purposes

The surveyed Bignoniaceae species, including Bignonia magnifica, Campsis grandiflora, C. radicans, Crescentia alata, Dolichandrone serrulata, D. spathacea, Fernandoa adenophylla, Handroanthus chrysanthus, Jacaranda mimosifolia, Kigelia africana, Mansoa alliacea, Mayodendron igneum, Millingtonia hortensis, Podranea ricasoliana, Pyrostegia venusta, Radermachera yunnanensis, Spathodea campanulata, Tabebuia aurea, T. pallida, T. rosea, Tecoma stans, T. stans cv. ‘Thong Urai Micky Mouse’ and Tecomaria capensis ‘Aurea’, are widely cultivated for ornamental purposes in the region (Table 1). These species are valued for their striking flowers, vibrant colors, and attractive growth forms, making them popular choices for landscaping, urban beautification, and private gardens.

These plants can be found in a variety of public and private spaces, including home gardens, temples, educational institutions, government offices, hotels, and resorts. For example, species such as Jacaranda mimosifolia, Tabebuia rosea, and Handroanthus chrysanthus are often planted in public parks, along roadways, and in hotel or resort gardens to enhance the aesthetic appeal of these spaces. Campsis grandiflora and Tecoma stans are frequently used in educational institutions landscapes, while Spathodea campanulata and Radermachera yunnanensis are often seen around government offices and temples, where they provide shade and ornamental value. The cultivation of these species for ornamental use not only enhances the beauty of these locations but also contributes significantly to the local horticultural economy, with many plants being sold in local markets and nurseries. Their widespread use underscores their importance as decorative plants and valuable economic assets for local communities.

3.8.6. Bignoniaceae Used as Medicines

The survey found that several Bignoniaceae species are used as medicines in the region (Table 1). These include Crescentia alata, C. cujete, Dolichandrone serrulata, D. spathacea, Fernandoa adenophylla, Millingtonia hortensis, Oroxylum indicum, Spathodea campanulata, Tabebuia rosea, and Tecoma stans. These species are utilized in traditional medicine for treating a variety of ailments, highlighting their significant role in the local healthcare practices and their cultural importance in the region.

3.8.7. Bignoniaceae Used in Rituals and Ceremonial Activities

The study found that two Bignoniaceae species, Millingtonia hortensis and Tecoma stans, were widely used in rituals and various activities (Table 1). The flowers of these plants were commonly offered to Buddha and used as ornamental plants in homes, as they were believed to bring prosperity and wealth.

3.9. Informant Consensus Factor (F_ic) of Bignoniaceae in Maha Sarakham Province

The Informant Consensus Factor (F_ic) was calculated to assess the degree of agreement among informants regarding the medicinal use of Bignoniaceae species in Maha Sarakham Province (

Table 8. Informant consensus factor (F_ic) of Bignoniaceae used as medicine in Maha Sarakham Province.

Group of Ailments	Number of Use Report (Nur)	Number of Taxa (Nt)	Fic
Skin	9	6	0.38
Infections	4	2	0.67
Obstetrics, gynecology, and urinary-tract disorders	2	1	1.00
Central nervous system	5	3	0.50
Gastro-intestinal system	26	8	0.72
Respiratory system	7	2	0.83
Nutrition and blood	8	4	0.57
Infections	3	2	0.50

). To categorize the medicinal uses of Bignoniaceae species reported by informants, we grouped ailments into major physiological and ethnomedicinal categories based on previous ethnobotanical literature and the World Health Organization’s International Classification of Diseases (ICD-11) [25]. The categories identified in our study included the following: (1) skin conditions, (2) infections, (3) obstetrics, gynecology, and urinary tract disorders, (4) central nervous system disorders, (5) gastrointestinal system disorders, (6) respiratory system disorders, and (7) nutrition and blood-related conditions. The F_ic values varied across different ailment categories, ranging from 0.38 to 1.00. The highest consensus (F_ic = 1.00) was observed for the treatment of obstetrics, gynecology, and urinary tract disorders, although this category had the lowest number of use reports (N_ur = 2), indicating a unanimous agreement on a single taxon. The respiratory system category showed a high consensus as well (F_ic = 0.83), followed by the gastrointestinal system (F_ic = 0.72), which also had the highest number of use reports (N_ur = 26), suggesting strong shared knowledge and widespread use in this category. Moderate consensus was found in infections (F_ic = 0.67), the central nervous system (F_ic = 0.50), and nutrition and blood-related conditions (F_ic = 0.57). The lowest consensus was observed in the treatment of skin-related ailments (F_ic = 0.38), reflecting more variability in plant use among informants. It is also noted that the infections category appeared twice in the dataset with slightly differing values, indicating a potential data overlap or classification discrepancy.

3.10. Fidelity Level (FL) of Bignoniaceae in Maha Sarakham Province

The analysis of Fidelity Level (FL) among the documented species within the Bignoniaceae family reveals important insights into the consensus among informants regarding the specific therapeutic uses of these plants. As a key metric in ethnobotanical studies, FL serves to highlight the degree of cultural agreement and the perceived efficacy of plant-based treatments for particular ailments.

In this study, Spathodea campanulata exhibited the highest Fidelity Level (FL = 71.43%), with its bark exclusively cited for the treatment of constipation. This high level of agreement suggests strong cultural validation and therapeutic relevance within the local traditional knowledge system. Similarly, Tabebuia rosea demonstrated a high FL (66.67%) for its use in treating stomach pain and diarrhea, while Fernandoa adenophylla achieved an FL of 66.67% for treating flatulence, particularly with the use of its bark.

Other species with notable FL values include Tecoma stans, with an FL of 75.00% for treating diabetes using bark decoctions, and Crescentia alata, which showed an FL of 60.00% for wound healing and bleeding control when using leaf-based preparations.

Moderate FL values (40–60%) were observed in species such as Crescentia cujete and Dolichandrone serrulata, each used across a range of ailments including gastrointestinal, respiratory, and neurological conditions. These intermediate FL values reflect both a significant level of agreement among informants and the multipurpose nature of these species.

Lower FL values (<40%) were common among species reported for multiple therapeutic uses. For example, Oroxylum indicum was cited for treating wounds, abscesses, and heartburn, resulting in more dispersed informant consensus (FL = 14.29–57.14%). Similarly, Millingtonia hortensis and Dolichandrone spathacea were reported for diverse uses ranging from treating tuberculosis and fever to functioning as hematinic agents, leading to moderate to low FL values.

A detailed summary of the species, used parts, preparation methods, routes of administration, therapeutic applications, and corresponding Fidelity Levels is presented in

Table 9. Fidelity Level (FL) of Bignoniaceae used as medicine in Maha Sarakham Province.

Scientific Name	Iu	Ip	FL	Used Parts	Preparation	Method of Uses	Ailments	Group of Ailments
Crescentia alata Kunth	3	5	60.00	Leave	Boil with water and then filter only the liquid	Drink	Heals wounds and helps stop bleeding	Skin
	2	5	40.00	Leave	Boil with water and then filter only the liquid	Drink	Treat dysentery	Infections
Crescentia cujete L.	2	5	40.00	Heartwood	Boil with water and then filter only the liquid	Drink	Relieve fatigue for women after childbirth	Obstetrics, gynecology and urinary-tract disorders
	1	5	20.00	Leave	Grind finely	Use externally	Relieve headache	Central Nervous System
	2	5	40.00	Bark	Boil with water and then filter only the liquid	Drink	Treat diarrhea	Gastro-intestinal system
Dolichandrone serrulata (Wall. ex DC.) Seem.	2	10	20.00	Root	Boil with water and then filter only the liquid	Drink	Relieve phlegm	Respiratory System
	3	10	30.00	Bark	Boil with water and then filter only the liquid	Drink	Relieves flatulence and bloating	Gastro-intestinal system
	1	10	10.00	Leave	Grind finely	Use externally	Heals wounds and helps stop bleeding	Skin
	2	10	20.00	Inflorescence	Boil with water and then filter only the liquid	Drink	Relieve phlegm	Respiratory System
	2	10	20.00	Seed	Boil with water and then filter only the liquid	Drink	Treat epilepsy	Central Nervous System
Dolichandrone spathacea (L.f.) K.Schum.	2	8	25.00	Root	Boil with water and then filter only the liquid	Drink	Nourishes the blood	Nutrition and blood
	2	8	25.00	Seed	Boil with water and then filter only the liquid	Drink	Treat epilepsy	Central Nervous System
	1	8	12.50	Leave	Boil with water and then filter only the liquid	Drink	Treat fever	Infections
	3	8	37.50	Bark	Boil with water and then filter only the liquid	Drink	Relieves flatulence and bloating	Gastro-intestinal system
Fernandoa adenophylla (Wall. ex G.Don) Steenis	1	6	16.67	Seed	Boil with water and then filter only the liquid	Drink	It functions as a hematinic agent	Nutrition and blood
	4	6	66.67	Bark	Boil with water and then filter only the liquid	Drink	Treats flatulence	Gastro-intestinal system
	1	6	16.67	Leave	Grind finely	Use externally	Treat wounds	Skin
Millingtonia hortensis L.f.	2	7	28.57	Inflorescence	Rolled into a cigarette to smoke	Smoke	It functions as a hematinic agent	Nutrition and blood
	2	7	28.57	Root	Boil with water and then filter only the liquid	Drink	Treat tuberculosis	Infections
	3	7	42.86	Bark	Boil with water and then filter only the liquid	Drink	Treat cough	Respiratory system
Oroxylum indicum (L.) Kurz	1	7	14.29	Bark	Grind finely	Use externally	Treat wounds	Skin
	2	7	28.57	Bark	Grind finely	Use externally	Treat abscess	Infections
	4	7	57.14	Bark	Boil with water and then filter only the liquid	Drink	Treats heartburn	Gastro-intestinal system
Spathodea campanulata P.Beauv.	5	7	71.43	Bark	Boil with water and then filter only the liquid	Drink	Treat constipation	Gastro-intestinal system
	2	7	28.57	Bark	Grind finely	Use externally	Treat wounds	Skin
Tabebuia rosea (Bertol.) DC.	4	6	66.67	Leave	Boil with water and then filter only the liquid	Drink	Treat of stomach pain or diarrhea	Gastro-intestinal system
	2	6	33.33	Leave	Grind finely	Apply to skin	Treat a wound	Skin
Tecoma stans (L.) Juss. ex Kunth	1	4	25.00	Inflorescence	Eat fresh, cooking	Eat	Treat of gastrointestinal	Gastro-intestinal system
	3	4	75.00	Bark	Boil with water and then filter only the liquid	Drink	Treat of diabetes	Nutrition and blood

.

3.11. Economic Value of Bignoniaceae in Maha Sarakham Province

A total of 27 Bignoniaceae plant species were recorded as being commercially cultivated in Maha Sarakham Province. The economic data included price ranges per pot, average price per pot, number of pots sold per year, and the calculated economic value (EV) per species (

Table 10. List of Bignoniaceae plants used for commercial cultivation along with their price ranges, average price per pot, number of pots sold per year, and economic value in Maha Sarakham Province.

Scientific Name	Price (THB/Pot)		Average Price per Pot (Pp)	Number of Pots Sold per Year (Np)	Economic Value (EV)
	Min	Max
Bignonia magnifica W.Bull	60	100	80.00	120	9600.00
Campsis grandiflora (Thunb.) K.Schum.	150	290	220.00	135	29,700.00
Campsis radicans (L.) Bureau	50	199	124.50	132	16,434.00
Crescentia alata Kunth	1500	2000	1750.00	60	105,000.00
Crescentia cujete L.	450	520	485.00	80	38,800.00
Dolichandrone serrulata (Wall. ex DC.) Seem.	1500	10,000	5750.00	24	138,000.00
Dolichandrone spathacea (L.f.) K.Schum.	500	1000	750.00	36	27,000.00
Fernandoa adenophylla (Wall. ex G.Don) Steenis	50	100	75.00	55	4125.00
Handroanthus chrysanthus (Jacq.) S.O.Grose	150	350	250.00	130	32,500.00
Jacaranda mimosifolia D.Don	1200	1500	1350.00	100	135,000.00
Kigelia africana (Lam.) Benth.	350	1000	675.00	45	30,375.00
Mansoa alliacea (Lam.) A.H.Gentry	100	150	125.00	160	20,000.00
Markhamia stipulata (Wall.) Seem.	100	150	125.00	155	19,375.00
Mayodendron igneum (Kurz) Kurz	100	1500	800.00	84	67,200.00
Millingtonia hortensis L.f.	69	200	134.50	110	14,795.00
Oroxylum indicum (L.) Kurz	45	100	72.50	170	12,325.00
Podranea ricasoliana (Tanfani) Sprague	65	199	132.00	155	20,460.00
Pyrostegia venusta (Ker Gawl.) Miers	150	200	175.00	105	18,375.00
Radermachera yunnanensis C.Y.Wu & W.C.Yin	45	180	112.50	115	12,937.50
Spathodea campanulata P.Beauv.	59	199	129.00	120	15,480.00
Stereospermum neuranthum Kurz	35	110	72.50	125	9062.50
Tabebuia aurea (Silva Manso) Benth. & Hook.f. ex S.Moore	250	500	375.00	140	52,500.00
Tabebuia pallida (Lindl.) Miers	80	400	240.00	150	36,000.00
Tabebuia rosea (Bertol.) DC.	65	139	102.00	150	15,300.00
Tecoma stans (L.) Juss. ex Kunth cv. ‘Thong Urai Lueang’	50	120	85.00	175	14,875.00
Tecoma stans (L.) Juss. ex Kunth cv. ‘Thong Urai Micky Mouse’	300	890	595.00	163	96,985.00
Tecomaria capensis ‘Aurea’	80	250	165.00	120	19,800.00

Note: Prices are listed in US dollars based on the exchange rate of 1 USD = 36.5 THB as of 5 May 2025. These prices represent the sale amounts without specifying the intended use by the customers.

).

The highest economic value (EV) was recorded for Dolichandrone serrulata, amounting to 138,000 THB per year, followed by Jacaranda mimosifolia (135,000 THB), Crescentia alata (105,000 THB), and Tecoma stans cv. ‘Thong Urai Micky Mouse’ (96,985 THB). These high EVs were generally the result of either high average prices per pot, substantial sales volume, or a combination of both.

The species with the highest average price per pot was Dolichandrone serrulata at 5750 THB, while the lowest was Stereospermum neuranthum at 72.50 THB. Tecoma stans cv. ‘Thong Urai Lueang’ showed the highest annual volume sold with 175 pots, although its lower average price (85.00 THB/pot) limited its total economic contribution (14,875 THB).

Species with moderate prices and consistent sales, such as Tabebuia aurea (375.00 THB/pot, 140 pots/year), also demonstrated strong economic returns (52,500 THB). Conversely, low-cost species like Fernandoa adenophylla (75.00 THB/pot) and Stereospermum neuranthum (72.50 THB/pot) contributed the least in terms of economic value (4125 THB and 9062.50 THB, respectively).

The data indicate that both price and market demand influence the commercial success of Bignoniaceae species in the region. High-value ornamental species like Jacaranda mimosifolia, Crescentia alata, and Dolichandrone serrulata represent key economic assets in the local nursery trade.

4. Discussion

The present study reveals a moderate to high diversity of Bignoniaceae in Maha Sarakham Province, with 27 species across 21 genera. This diversity reflects the adaptability of Bignoniaceae to local environmental conditions. The dominance of monotypic genera suggests a broad but sparse distribution, likely shaped by habitat specificity, dispersal limitations, and historical biogeography.

In comparison, earlier ethnobotanical studies reported much lower Bignoniaceae representation. Saisor et al. [8] found only Millingtonia hortensis among 101 species in a forested area, while Saensouk et al. [4] recorded only Oroxylum indicum from local markets. Although valuable, these studies highlight the limited visibility of Bignoniaceae in broader plant surveys.

Our province-wide, family-focused survey, based on interviews with 260 informants and supporting fieldwork, revealed significantly greater diversity. By incorporating ethnobotanical indices such as SUV, RFC, CI, and CFSI, this study not only documents species richness but also emphasizes their cultural and ecological importance. The comparison underscores how thematic and spatial focus can shape research outcomes and affirms the value of targeted taxonomic studies in uncovering the full extent of traditional plant knowledge, particularly for underexplored families like Bignoniaceae.

The distribution of Bignoniaceae genera in Maha Sarakham Province reflects both ecological adaptation and human influence. Genera like Bignonia, Jacaranda, Kigelia, and Spathodea are notable for their ornamental and ecological roles, often linked to natural occurrence and anthropogenic introduction in urban or cultivated areas. In contrast, genera with higher species richness such as Tabebuia, Campsis, Crescentia, Dolichandrone, and Tecoma suggest localized diversification or successful naturalization, likely due to broader ecological tolerance or reproductive strategies favoring establishment across varied habitats [26,27]. This uneven species distribution mirrors global Bignoniaceae diversity patterns, where adaptive radiation and widespread cultivation shape genus dominance [28,29]. The presence of native genera like Oroxylum and Stereospermum further underscores the integration of indigenous flora in the region.

Phenological patterns indicate seasonal reproductive strategies adapted to the tropical monsoon climate. Peak flowering in March coincides with the late dry season, optimizing pollination efficiency through increased pollinator activity and floral visibility [30,31]. Reduced flowering during the peak rainy season (August) likely results from environmental stresses such as heavy rainfall and humidity limiting reproductive success [32]. The bimodal flowering observed towards year-end reflects phenological flexibility in response to climatic variability [33]. Fruit production follows a more dispersed temporal pattern, with staggered peaks in May and November that may reduce competition for dispersers and predation risk [34,35]. The consistent predominance of flowering over fruiting highlights additional biotic and abiotic constraints influencing successful fruit development, including pollinator availability and environmental conditions [36,37,38,39].

The reproductive phenology of Bignoniaceae in northeastern Thailand is strongly influenced by seasonal cues, reflecting adaptive strategies to the region’s environmental conditions. Understanding these patterns is crucial for effective management of flowering tree resources in landscaping, reforestation, and conservation efforts [40].

Species Use Values (SUV) reveal the cultural, economic, and ecological significance of Bignoniaceae species to local communities. High-use species such as Dolichandrone serrulata, D. spathacea, Oroxylum indicum, Millingtonia hortensis, and Tecoma stans are deeply embedded in traditional medicine, rituals, and ornamental cultivation, highlighting their multifunctional roles and adaptability to local landscapes [5,7,8,41,42,43,44,45]. Medium-use species contribute primarily as ornamentals and occasional sources of firewood or medicine, illustrating the varied utility even among less prominent taxa [46,47]. Low-use species, while mostly ornamental, may possess untapped ethnobotanical potential due to limited knowledge or recent introduction, suggesting avenues for future exploration [46].

At the genus level, Genera Use Values (GUVs) emphasize the prominence of Dolichandrone, Millingtonia, and Oroxylum as culturally and ecologically important groups, warranting attention in conservation and sustainable use initiatives [18,48]. Medium-use genera like Tecoma, Fernandoa, and Spathodea maintain important roles mainly in ornamentals and traditional uses, while low-use genera such as Markhamia, Kigelia, and Crescentia—primarily valued ornamentally—present opportunities for further ethnobotanical research and community engagement to enhance local biodiversity and livelihoods [4,49,50,51,52,53].

The positive correlation between Relative Frequency of Citation (RFC) and Species Use Value (SUV) indicates that widely known Bignoniaceae species in Maha Sarakham Province, such as Dolichandrone serrulata, D. spathacea, and Oroxylum indicum, hold multifaceted roles in medicine, ornamentation, and rituals, reflecting their integral place in local cultural and economic systems [4,19]. However, discrepancies between RFC and SUV—exemplified by Tecoma stans and Tecomaria capensis ‘Aurea’—highlight how localized knowledge enhances species’ multifunctionality despite lower citation rates, emphasizing the value of specialized uses within communities [46,49]. Conversely, species like Tabebuia rosea exhibit broad recognition but narrower functional roles, predominantly ornamental [54], while species with low RFC and SUV, such as Markhamia stipulata and Kigelia africana, currently possess limited ethnobotanical relevance but remain important for biodiversity and potential future uses [55].

Cultural Significance Index (CI) values further underscore the prominence of Oroxylum indicum, Millingtonia hortensis, and Dolichandrone serrulata as keystone species in cultural practices, including rituals, medicine, and commercial cultivation, reflecting their multifaceted contributions to the region’s socio-ecological landscape [8,18,41]. Species with moderate CI, such as Tecoma stans and Tabebuia rosea, illustrate more specialized cultural roles, primarily aesthetic, which points to niche contributions within local communities [56]. The concentration of cultural importance in ornamentals (CI = 2.34), followed by commercial cultivation and food uses, highlights the significant ecological and economic roles these species fulfill, while lower CI values in medicine, firewood, dyes, rituals, and handicrafts suggest more specialized or less frequent applications possibly constrained by availability or knowledge [57,58,59].

The Cultural Food Significance Index (CFSI) reveals that Dolichandrone serrulata and D. spathacea are central to local food and medicinal traditions, with high citation, use frequency, and versatility contributing to their cultural prominence [7,8,60,61,62,63,64]. Other species like Oroxylum indicum and Millingtonia hortensis also play important, though more specialized, roles in culinary practices, reflecting diverse but focused contributions to local diets [4,8,41]. In contrast, species such as Spathodea campanulata and Stereospermum neuranthum show limited involvement in food culture, highlighting variation in species’ utilitarian significance [7,50]. Moderate CFSI values for Tabebuia rosea and Crescentia species indicate their distinct but less widespread culinary uses, demonstrating the heterogeneity of food-related ethnobotanical knowledge [4,8,41].

These findings highlight the need to document and safeguard culturally significant species and practices that may be at risk due to urbanization, generational knowledge loss, or shifting land use. Future research should explore community-led conservation strategies and support educational initiatives to revitalize ethnobotanical knowledge systems, ensuring their transmission and integration into regional development and biodiversity planning.

The combined indices emphasize that while some Bignoniaceae species are culturally and economically central due to their multifunctionality and broad recognition, others contribute through specialized or emerging roles, underscoring the importance of preserving ethnobotanical knowledge and exploring underutilized species to support local biodiversity, cultural heritage, and sustainable livelihoods [4,18,46,49,57,65,66,67].

The diverse utilization of Bignoniaceae species in Maha Sarakham Province underscores their integral role in local culture, economy, and ecology. The predominance of ornamental uses (44.23%) highlights their cultural importance in beautifying urban and rural landscapes, supporting horticultural economies, and contributing to regional aesthetics [4,8,16,18,41,53,68,69]. Additionally, the use of these species for traditional dyes, firewood, food, handicrafts, and spiritual practices illustrates their multifunctional value across livelihoods and cultural expressions [4,8,41,51,70,71,72,73,74,75,76,77,78,79].

Medicinal applications (19.23%) further demonstrate the significance of Bignoniaceae in traditional healthcare, where species address various common ailments, reinforcing their enduring relevance in local health systems [46,49,60,79,80]. Together, these uses reflect a deep cultural and ecological connection, emphasizing the importance of conserving these species to sustain both biodiversity and cultural heritage [4,8,16,18,41].

Interviews revealed that local people acquire Bignoniaceae species for medicinal purposes through two main ways: harvesting plants directly from their home gardens or nearby natural habitats, and purchasing from local herbalists or markets. Species that are commonly cultivated and readily available are often collected from personal gardens, while less accessible species or fresh materials are typically bought from herbal vendors. This dual approach reflects the flexibility and practicality of traditional plant use in the community.

Economically, Bignoniaceae species contribute substantially to the local horticultural market, with commercial cultivation driven by both high-value species like Dolichandrone serrulata and popular, affordable species such as Tecoma stans cv. ‘Thong Urai Lueang’ [4,81,82,83,84,85]. The balance between price and demand shapes market dynamics, supporting diverse consumer needs and livelihoods. Moreover, the adaptability and resilience of many Bignoniaceae species to local climatic conditions enhance their horticultural value and suitability for sustainable landscaping in Northeastern Thailand [4,16,57].

These findings highlight the multifaceted ecological, cultural, and economic significance of Bignoniaceae in Maha Sarakham Province, underscoring their vital role in supporting local communities and promoting sustainable development.

Compared to major botanical families in Thailand such as Asteraceae, Convolvulaceae, Leguminosae, Piperaceae, Smilacaceae, and Zingiberaceae [16,18,23,53,86,87,88,89,90,91,92], the Bignoniaceae family occupies a more specialized yet culturally significant niche. Its prominence is particularly noted in ornamental, medicinal, and ritual uses. This pattern of culturally meaningful, though relatively limited, utilization is also reflected across Southeast Asia and South America. Despite having fewer species, Bignoniaceae species in these regions hold substantial ecological and ethnobotanical importance [27,28,31,46,48,51,54,57,80].

Within Maha Sarakham Province and more broadly in Thailand, several Bignoniaceae species such as Markhamia stipulata and Kigelia africana remain largely underutilized in ethnobotanical contexts. These species represent untapped potential for further research, conservation efforts, and sustainable community use. Their presence underscores a gap in both biodiversity knowledge and cultural application that could be addressed in future studies.

Regarding non-native Bignoniaceae species introduced to Thailand, many retain traditional uses similar to those documented in their regions of origin. For example, Tecoma stans and Spathodea campanulata are used medicinally and ornamentally in Thailand much like in the Americas, their native range [31,51]. Understanding the approximate introduction timelines of such species and how their uses align with ancestral knowledge can shed light on processes of cultural adaptation and exchange, enriching the ethnobotanical landscape of Thailand.

The high cultural and utilitarian value attributed to Dolichandrone serrulata, D. spathacea, and Oroxylum indicum in Maha Sarakham Province is consistent with reports from other parts of Thailand and Southeast Asia. These species are multifunctional, serving roles in traditional medicine, ornamentation, and ritual practices. For instance, Oroxylum indicum is widely recognized in India for its medicinal fruits and seeds, and it is commonly used to treat respiratory and digestive ailments [42]. This corroborates its longstanding cultural significance and medicinal efficacy across Asia.

While ethnobotanical documentation for Dolichandrone serrulata outside Thailand is limited, pharmacological studies highlight its antioxidant and α-glucosidase inhibitory activities, underscoring its medicinal potential locally [93]. Similarly, Dolichandrone spathacea has demonstrated potent bioactivities such as xanthine oxidase inhibition, as reported in recent Vietnamese research [94]. The combined evidence of widespread use, pharmacological validation, and cultural integration suggests that accessibility, therapeutic efficacy, and deep-rooted cultural knowledge contribute to the prominence of these species both regionally and locally.

5. Conclusions

This study provides a comprehensive ethnobotanical assessment of Bignoniaceae species in Maha Sarakham Province, highlighting their multifaceted roles in local ecosystems and communities. A total of 27 species were documented, demonstrating considerable taxonomic diversity and a wide range of uses across medicinal, ornamental, cultural, and practical domains. Seasonal phenology patterns revealed distinct flowering and fruiting periods, reflecting adaptive strategies to the region’s climate and offering insights relevant to conservation and sustainable management. Cultural significance emerged as a central theme, with several species deeply embedded in local traditions, rituals, and belief systems. Quantitative indices—including the species use value (UV), genera use value (GUV), relative frequency of citation (RFC), cultural importance index (CI), and cultural food significance index (CFSI)—confirmed the high cultural and utilitarian value of species such as Dolichandrone serrulate, D. spathacea, and Oroxylum indicum. In addition to their ethnobotanical value, many Bignoniaceae species demonstrate remarkable horticultural potential due to their adaptability, ornamental appeal, and usefulness in sustainable landscaping. Economically, species like Dolichandrone serrulata, Jacaranda mimosifolia, and Tecoma stans contribute significantly to the local nursery and ornamental plant trade, supporting livelihoods and the regional green economy. These findings not only underscore the ethnobotanical richness of the region but also point to the urgent need to document and safeguard traditional knowledge amid rapid socio-environmental changes. Future research should explore long-term conservation strategies, socio-economic impacts, and the resilience of cultural practices linked to plant use. Importantly, integrating traditional knowledge into local and regional policy frameworks can enhance biodiversity conservation, promote cultural heritage preservation, and inform sustainable development planning. This study offers a valuable foundation for interdisciplinary efforts linking ethnobotany, conservation, and policy in Northeastern Thailand and beyond.