Introduction
Fabaceae Lindl. nom. alt. (Papilionaceae Giseke nom. cons.) is the third largest family of flowering plants after Orchidaceae and Asteraceae, with approximately 483 genera and about 12,000 species mainly distributed in tropical and subtropical region of the World (Lewis et al. 2005). The family is an important in a diversity of ecosystems; members of it present and often dominant in nearly every vegetation type on earth, from tropical rain forests to deserts and alpine tundra (Wojciechowski 2003). In India, there are about 147 genera, 805 species, 33 subspecies, 155 varieties and 14 forma of legumes (Sanjappa 1991, Sanjappa 1995;Dave 2004;Chaudhary and Khan 2005; Ansari 2008; Jabbar et al. 2010; Aitawade et al. 2012; Chavan et al. 2013; Gaikwad et al. 2014d). The higher concentration of legumes are in peninsular India (about 619 species) and northeast India including eastern Himalaya (about 767 species) corresponding to two hotspot areas in India. About 83 genera, 326 species, 2 subspecies, 57 varieties and 1 forma of Fabaceae occur in Maharashtra (Almeida 1998; Kothari 2000; Naik 1998; Aitawade et al. 2012; Gaikwad et al. 2012; Chavan et al. 2013; Gaikwad et al. 2014a, Gaikwad et al. 2014c, Gaikwad et al. 2014d).
A hilly terrain and semi-arid general climate of Balaghat Ranges supports unique tropical dry deciduous forests and thorny scrub vegetation with vast grasslands. The grasslands of Balaghat Ranges are unique and popularly known as Indian Savannas. The herbaceous vegetation of Balaghat Ranges is notable as it amounts to 59% of the whole flora. The members of the Fabaceae are dominant in herbaceous vegetation. The genera like Alysicarpus Neck. ex Desv., Crotalaria L., Indigofera L., Desmodium Desv. and Vigna Savi are most diversified in the Balaghat region. In spite of rich diversity, the legumes of Balaghat Ranges remained neglected or ignored by earlier workers probably due to the general dry climate of the region. However, some sporadic efforts have been made to study the legumes of Balaghat in the last hundred years such as Jain (1961), Jagtap (1965), Naik (1966), Bhagvat (1968), Naik (1969), Naik (1970), Wadood Khan (1982), Mahabale (1987) and Naik (1998). Thus, comprehensive and reliable account of legumes of Balaghat Ranges does not exist. Hence, the present study was undertaken in 2009 as Ph.D. work to produce an up-to-date account of the legumes of Balaghat Ranges.
Materials and methods
Study area
Balaghat Ranges are eastern spur of Western Ghats of India lie in between 18°47'40.26" - 18°32'29.28"N latitude and 75°20'26.90" - 76°48'56.18"E longitude, spread in Ahmednagar, Beed, Latur, Osmanabad and Solapur districts of the Maharashtra State of India in the basins of river Manjra and its tributaries Bori, Lendi, Manyad, Terna and Tiru. Balaghat occupies an area of about 18,111.34 Km2 (Fig. 1). The terrain of Balaghat shows hills and hillocks of varying heights (450 to 850 m), which support unique tropical dry deciduous forests, open scrub jungles and vast grasslands. The weather in general is dry and said to be moderately extreme. An annual temperature ranges between 27.7oC - 42oC and the relative humidity is extremely low (35-50%) for major part of the year while it is highest (75%) during the monsoon season (June-October). The average annual rainfall is about 729 mm mainly from June to October.
Data collection
First of all a list of taxa of the family Fabaceae of the Balaghat Ranges was prepared by referring to all available literature and specimens deposited in various herbaria. After that, field-visits of 1-3 days duration were undertaken to nooks and corners of Balaghat Ranges for plant collection. During the field visits, information on habit, habitat, phenological data, GPS data and present status were gathered. Three specimens were collected of each species and prepared voucher specimens following standard herbarium techniques (Rao and Sharma 1990). The specimens are deposited in the herbarium of Walchand College, Solapur, Maharashtra (WACS). Identification of taxa was confirmed with the help of available literature such as Cooke (1958), Babu et al. (1987), Sanjappa (1995), Almeida (1998), Naik (1998), Kothari (2000), Lakshminarasimhan (2001), Tomooka et al. (2002a), Tomooka et al. (2002b), Dave (2004), Chaudhary and Khan (2005), Ansari (2008), Jabbar et al. (2010), Toomoka et al. (2011) and Aitawade et al. (2012). Doubtful and interesting identifications were confirmed by their direct comparison with authentically identified specimens deposited in various herbaria such as Herbarium of Botanical survey of India, Pune (BSI); Blatter Herbarium, St. Xavier’s College, Mumbai (BLAT) and BAMU Herbarium, Aurangabad (BAMUA). The botanical name of the taxa have been verified with International Plant Name Index (IPNI). The genera, species and infraspecific taxa are alphabetically arranged in the present paper. Some important plants are featured in photographs (Figs 2, 3, 4, 5).
Discussion
The present study is an outcome of intensive and extensive field explorations and herbarium studies carried out between the years 2009-2013. The legumes of Balaghat Ranges show wide range of species diversity and growth forms. The total number of leguminous taxa reported for the Maharashtra State as on today is 344 (Almeida 1998; Kothari 2000; Lakshminarasimhan 2001). For Balaghat Ranges, the number of leguminous taxa works out to be 144. Therefore, percentage of leguminous taxa of Balaghat Ranges out of whole legumes of Maharashtra will be 41.86%. The members of Fabaceae are dominant in herbaceous vegetation and more speciose in genera like Crotalaria (23 taxa), Indigofera (16 taxa), Alysicarpus (14 taxa), Vigna (11 taxa) and Desmodium (8 taxa). The area under investigation is relatively small for the assessment of endemism of leguminous elements. It is continuous with the surrounding areas on the Deccan plateau and there is no obvious natural boundary between this and neighboring region, which can hold any endemic taxa. On the other hand, comparative statistical analysis of the leguminous species recorded so far from Balaghat Ranges with those of the neighboring regions reveals highest proportion of similarities. However, Alysicarpus luteo-vexillatus, A. pubescens var. vasavadae, Crotalaria decasperma, C. filipes, C. hirta, C. leptostachya, C. linifolia, C. notonii, Indigofera deccanensis, I. glandulosa var. sykesii, I. trifoliata var. duthiei and Vigna indica occur in Balaghat Ranges that are endemic to India. Among 12 endemic species, Indigofera deccanensis is known only from two localities with 907 Km2 extent of occurrence, 10 Km2 area of occupancy and severely fragmented small subpopulations. Hence, it falls into Critically Endangered IUCN Red List category (Mishra and Singh 2001; Gaikwad et al. 2014b).
The legumes of Balaghat Ranges have many actual and potential uses such as food, fodder, industrial lubricants, natural dyes, medicine and sources of edible oil and timber; and indirectly affect socio-economic development of the region. Some nine legumes are used as vegetables in Balaghat Ranges that include Canavalia gladiata, Cyamopsis tetragonolobus, Lablab purpureus, Phaseolus vulgaris, Pisum sativum, Pisum arvense, Sesbania grandiflora, Trigonella foenum-graecum, Vigna unguiculata var. cylindrica and eight legumes namely Cajanus cajan, Cicer arietinum, Lathyrus sativus, Lens culinaris, Macrotyloma uniflorum, Vigna aconitifolia, V. mungo and Vigna radiata are cultivated as pulses. Arachis hypogeal and Glycine max are popular sources of edible oil. Medicago sativa and Stylosanthes hamata are cultivated as forage crops. Dalbergia sissoo, D. melanoxylon, D. latifolium and Pterocarpus marsupium are known for their quality timber whereas Butea monosperma, Gliricidia sepium and Erythrina suberosa are used as fuel wood. Flowers of Butea monosperma and Indigofera tinctoria are famous sources of natural dyes; later species is cultivated on commercial scale for yielding Indigo-dye. Crotalaria juncea, Melilotus albus and M. indicus are best green manures used by farmers. Seeds of Pongamia pinnata are a challenging source of non-edible oil, which has commercial importance as industrial lubricant. A reputed biofertilizer is prepared from seed of Pongamia pinnata. About 14 legumes of Balaghat Ranges have medicinal potential that include Abrus precatorius, Butea monosperma, Clitoria ternatea var. pilosula, C. ternatea var. ternatea, Crotalaria verrucosa, Cullen corylifolia, Desmodium oojeinense, Mucuna pruriens, Pongamia pinnata, Pterocarpus marsupium, Tephrosia purpurea, Taverniera cuneifolia and Trigonella foenum-graecum. About 19 leguminous taxa are wild relatives of our food and fodder crops have resistance to pests and diseases, and abiotic stresses such as drought and salinity can be used in improvement of the quality and yield of crops (Table 1).