Journal of Threatened Taxa | www.threatenedtaxa.org | 26 April 2021 | 13(5): 18257–18282

 

ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) 

https://doi.org/10.11609/jott.6475.13.5.18257-18282

#6475 | Received 26 July 2020 | Final received 17 March 2021 | Finally accepted 10 April 2021

 

 

Legumes of Kerala, India: a checklist

 

Anoop P. Balan 1  & S.V. Predeep 2

 

1 KSCSTE-Malabar Botanical Garden and Institute For Plant Sciences, Kozhikode, Kerala 673014, India.

1 PG Department of Botany, Bishop Abraham Memorial College, Thuruthicad, Pathanamthitta, Kerala 689597, India

2 PG Department of Botany, SVR NSS College, T.P. Puram P.O., Vazhoor, Kottayam, Kerala 686505, India.

1 anooppb01@gmail.com (corresponding author), 2 predeepsv@gmail.com

 

 

 

Editor: M.K. Vasudeva Rao, Shiv Ranjani Housing Society, Pune, India. Date of publication: 26 April 2021 (online & print)

 

Citation: Balan.A.P. & S.V. Predeep (2021). Legumes of Kerala, India: a checklist. Journal of Threatened Taxa 13(5): 18257–18282. https://doi.org/10.11609/jott.6475.13.5.18257-18282

 

Copyright: © Balan & Predeep 2021. Creative Commons Attribution 4.0 International License.  JoTT allows unrestricted use, reproduction, and distribution of this article in any medium by providing adequate credit to the author(s) and the source of publication.

 

Funding: This study was initially funded by Kerala State Council for Science, Technology and Environment (KSCSTE), Department of Science & Technology, Government of Kerala through the project ‘Studies on the Legume Flora of Kerala state’ (No. 013/SRSLS/2005/CSTE) during the period 2006-2009. The first author received financial assistance from Science and Engineering Research Board, Department of Science and Technology, Government of India through the project PDF/2016/001936 during the period 2017-2019.

 

Competing interests: The authors declare no competing interests.

 

Author details: Anoop P. Balan is an Assistant Professor in the PG Department of Botany (SF), Bishop Abraham Memorial College, Thuruthicad, Pathanamthitta, Kerala. He was a National Post-Doctoral Fellow (SERB, Govt. of India) and Project Co-Ordinator (KSBB) at KSCSTE-Malabar Botanical Garden & Institute for Plant Sciences, Kozhikode, Kerala during the period 2017-2020. His area of interest is Plant taxonomy and Legume systematics. Dr. S.V. Predeep was retired as an Associate Professor in the PG Department of Botany, SVR NSS College, Vazhoor, Kottayam, Kerala. His area of interest is Legume systematics.

 

Author contribution: SVP designed and conceptualized the study. APB and SVP conducted field surveys, collection, identification and documentation of legumes from all districts of Kerala state. APB prepared the first draft of the manuscript and SVP contributed in further editions.

 

Acknowledgements: The authors are thankful to the Kerala State Council for Science, Technology & Environment, Department of Science & Technology, Government of Kerala for financial assistance. We are also grateful to the management of SVR NSS College, Vazhoor, Kottayam for the facilities provided for this work. First author is grateful to KSCSTE-Malabar Botanical Garden & Institute for Plant Sciences, Kozhikode, Kerala for various supports. The help given by Dr. A.J. Robi, BAM College, Thuruthicad, Dr. P.S. Udayan, Sree Krishna College, Guruvayur, Dr. N. Sasidharan, KFRI, Peecchi, Dr. Vivek C. Poulose, Botanical Survey of India, Port Blair and Dr. Rakesh G. Vadhyar, Botanical Survey of India, Coimbatore through photographs and literature are thankfully acknowledged. Thanks, are also due to Dr. V.P. Prasad, former Head of Office, Central National Herbarium, Botanical Survey of India, Kolkata and the curators of various Indian herbaria for their assistance during herbarium consultation. Support and assistance from the officials of Kerala State Forest Department was invaluable during the field studies and is also acknowledged with thanks.

 

 

 

Abstract: A checklist of the legumes of Kerala State is presented.  This exhaustive checklist is an outcome of extensive field surveys, collection, identification and documentation of family Leguminosae carried out across Kerala State during the period 2006–2019.  A total of 448 taxa were recorded under five subfamilies and 115 genera.  The majority of the legumes are herbs and shrubs, the rest being trees and woody climbers.  About 81 taxa are endemic to India, especially confined to the Western Ghats biodiversity hotspot, out of which 17 are endemic to  Kerala.  The state is home to two Critically Endangered and six Endangered legumes, facing severe threat of extinction.  Crotalaria is the dominant legume genus in the state with 62 taxa followed by Desmodium and Indigofera.  About 57 genera are represented by single species each.  Legumes are treated according to the latest phylogenetic classification of the Legume Phylogeny Working Group (LPWG).  Updated nomenclature, habit, native countries, voucher specimens, and images of endemic and lesser known legumes found in the state are provided.  Crotalaria multiflora var. kurisumalayana (Sibichen & Nampy) Krishnaraj & N. Mohanan is reduced as a synonym to C. multiflora (Arn.) Benth.

 

Keywords: Checklist, Crotalaria multiflora, endemic, Kerala, Leguminosae, LPWG, Western Ghats.

 

 

 

Introduction

 

Leguminosae with 770 genera and over 19,500 species (Lewis et al. 2013), are the third largest family of flowering plants after Orchidaceae and Asteraceae.  Legumes are a significant component of nearly all terrestrial biomes, distributed throughout the world in almost all habitats and are second only to the Poaceae in their importance to human beings.  The family is morphologically, physiologically, and ecologically exceptionally diverse, representing one of the most spectacular examples of evolutionary diversification in plants (LPWG 2017).  Legumes are grown agriculturally, primarily for their seeds called pulses, contributing 33% of the dietary protein nitrogen needs of humans (Vance et al. 2000).  Many legumes are able to do nitrogen fixation, through symbiotic association with Rhizobium bacteria within root nodules and thereby play an important ecological role in the terrestrial nitrogen cycle.  Considering the importance of legumes, the 68th session of the United Nations General Assembly declared the year 2016 as the International Year of Pulses for their popularisation internationally.

Leguminosae in India are represented by 1,297 taxa under 179 genera, of which about 23% are strictly confined to India (Sanjappa 1992).  Kerala, one of the species-rich states in the country, is exceptional because of its richness in biodiversity and endemism.  According to Nayar et al. (2006), Kerala represents about 4,694 species of flowering plants under 1,418 genera and 188 families.  The state constitutes only 1.18% of the geographical area of India but it accommodates about 27.57% of the flowering plants occurring in the country (Nayar et al. 2008).  Sasidharan (2004) and Nayar et al. (2006) published checklists of flowering plants of Kerala, primarly based on literature.  According to Sasidharan (2004), there are 381 legume species in Kerala under 93 genera out of which 82 taxa are endemic to India.  Nayar et al. (2006) enumerated 389 species of legumes in Kerala under 96 genera of which 85 taxa are restricted to India.  The latest treatment of Leguminosae in Kerala  is that of Murthy & Nair (2016), in which they enumerated 382 species of legumes under three distinct families, viz., Caesalpiniaceae, Fabaceae, and Mimosaceae with 17, 60, & 18 genera and with 56, 281, & 45 species, respectively.

Though Leguminosae are one of the most dominant families in the state and also highly important in the economic point of view, an exclusive legume flora of the state is still wanting.  To fill this lacuna, the authors have conducted extensive field surveys, collection, identification and documentation of all the legumes of the state during the last 14 years to produce a comprehensive account on the legume flora of Kerala.  Regarding this, recently three new leguminous taxa and seven new records have been reported from Kerala (Predeep et al. 2008, 2009; Predeep & Balan 2010; Balan & Predeep 2016; Balan et al. 2014, 2017).  The study was initially funded by the Kerala State Council for Science, Technology and Environment, Dept. of Science & Technology, Govt. of Kerala.  The present checklist is the first step before the release of a legume flora of Kerala and the list is prepared based on the authors’ own collections, and specimens deposited in various Indian herbaria and relevant literature.

 

Systematic Treatment

Leguminosae (nom. alt. Fabaceae) received its scientific name from earlier taxonomists due to its characteristic fruit (legume).  Since this name was long in usage even before the code was formulated, this name was conserved by the International Code of Nomenclature (ICN).  Another name Fabaceae based on the type genus Faba Mill. was proposed as an alternate name according to the provisions of ICN and both names are acceptable following Articles 18.5 and 18.6 of the Shenzhen Code (Turland et al. 2018).  The name Leguminosae or Fabaceae encompasses all the known leguminous plants under it.  Monocarpellary superior ovary with marginal placentation and leguminous fruit are the key characters of Leguminosae.

Earlier (and worth mentioning) treatment of the family Leguminosae are that of de Candolle (1825), who subdivided the family into four suborders (= subfamilies), namely, Papilionaceae, Swartzieae (now included in Papilionoideae), Mimoseae, and Caesalpineae.  This system was elaborated by Bentham (1865), who recognised three major groups within Leguminosae and whose classification formed the basis for all subsequent classifications of the family for the next 150 years.  Taubert (1894), Engler (1964), Thorne (1976, 2000), Polhill & Raven (1981), and many others also treated Leguminosae as one family with three subfamilies.  Some other researchers treated Mimosaceae, Caesalpiniaceae, and Papilionaceae as separate families (Takhtajan 1959, 1966, 1973, 1980; Hutchinson 1964, 1969, 1973; Cronquist 1968; Dahlgren 1983; Mabberley 1997).  Systematic considerations based on molecular evidences also recognize Leguminosae as a monophyletic family, with three subfamilies (Doyle et al. 2000; Lewis & Schrire 2003; Wojciechowski 2003; Lewis et al. 2005; Shipunov 2009; APG IV 2016; Judd et al. 2016).  Recent molecular-based phylogenetic studies (Bruneau et al. 2008; Bello et al. 2009, 2012; Sinou et al. 2009; Cardoso et al. 2012, 2013; Gagnon et al. 2013, 2016; Koenen et al. 2013; LPWG 2013a,b, 2017; Dugas et al. 2015), however, made sweeping changes in the systematics of Leguminosae.  The Legume Phylogeny Working Group-LPWG (2017) proposed a new subfamilial classification of Leguminosae, which is perhaps the most comprehensively sampled phylogenetic analysis of legumes to date.  All adequately sampled phylogenetic analyses of the family indicate that the monophyletic Mimosoideae and Papilionoideae are nested within a paraphyletic assemblage of caesalpinioid lineages.  LPWG (2017) recognized six subfamilies in Leguminosae: a recircumscribed Caesalpinioideae DC. (148 genera & ca. 4400 species), Cercidoideae LPWG (12 genera & ca. 335 species), Detarioideae Burmeist. (84 genera & ca. 760 species), Dialioideae LPWG (17 genera & ca. 85 species), Duparquetioideae LPWG (one genus & one species), and Papilionoideae DC. (503 genera & ca. 14,000 species).  The traditionally recognised subfamily Mimosoideae is a distinct clade nested within the recircumscribed Caesalpinioideae.  All the subfamilies, except the African subfamily Duparquetioideae, are well represented in Kerala.

 

 

MATERIALS AND METHODS

 

This checklist is the result of extensive field studies and repeated seasonal collections of plant specimens from Kerala during the period 2006 ̶2019.  The plant samples belonging to Leguminosae were collected from all areas of Kerala including coastal, midland, and highlands, all types of forest and non-forest areas in all seasons of the year.  Herbarium sheets were prepared following the method suggested by Bridson & Forman (1998) and are housed in the herbarium in the Malabar Botanical Garden & Institute for Plant Sciences, Kozhikode, Kerala (MBGH).  Identification was done with the help of pertinent literature including national and local floras (Hooker 1876, 1878; Bourdillon 1908; Rao 1914; Gamble 1918; Manilal & Sivarajan 1982; Manilal 1988; Ramachandran & Nair 1988; Vajravelu 1990; Mohanan & Henry 1994; Sasidharan & Sivarajan 1996; Sivarajan & Mathew 1997; Mohanan & Sivadasan 2002; Kumar et al. 2005; Sunil & Sivadasan 2009; Sasidharan 2011) and revisionary studies (Sanjappa 1986, 1995; Thothathri 1982, 1987; Babu et al. 1987; Nair 1989; Chakrabarty & Gangopadhyay 1996a,b; Singh 2001; Bandyopadhyay et al. 2006; Ansari 2008) and consultation of authentic specimens housed at CAL, CALI, KFRI, MH, TBGT & University College Herbarium, Thiruvananthapuram.  The species list is based primarily on author’s collections and specimens deposited in various Indian herbaria listed in Tables 1, 2, 3, with the exception of 39 reports from the literature.  The checklist is arranged according to the latest phylogenetic system of classification of legumes proposed by LPWG (2017).  Each species is arranged alphabetically under respective subfamilies.  Habit, native countries, selected voucher specimens and litereature references are provided for each species.  Plant names are updated following International Plant Names Index (IPNI—www.ipni.org), The Plant List (www.theplantlist.org) and Tropicos (www.tropicos.org).  The native range of each species is given on the basis of the International Legume Database and Information Service (ILDIS—www.ildis.org) and Plants of the World Online (www.plantsoftheworldonline.org).

 

 

RESULTS

 

Leguminosae (Fabaceae sensu lato) in Kerala  are represented by 448 taxa including 423 species, four subspecies and 21 varieties under 128 genera in five subfamilies (Tables 1, 2, 3; Images 1 ̶ 64).  Out of 448 taxa, 87 are introduced plants, either naturalized or under cultivation for various purposes.  Among the 361 indigenous legumes, Papilionoideae dominate with 269 species, one subspecies and 16 varieties under 64 genera.  Caesalpinioideae is represented by 53 taxa in 22 genera followed by Detarioideae (13/5), Cercidoideae (8/3), and Dialioideae (1/1).  Crotalaria is the dominant genus with 59 taxa, next comes Indigofera (26 taxa), Dalbergia (18 taxa), Tephrosia (13), and Vigna (13).  About 47 genera are represented by a single species only. Top 10 dominant genera are given in Fig. 1.

Life form analysis (Fig. 2) revealed that, out of the 361 indigenous legumes identified from the state, the majority are herbs (124) and shrubs (95) followed by climbers (78) and trees (64).

The district-wise analysis (Fig. 3) shows that Idukki is the legume-rich district with 267 taxa followed by Palakkad (236), Kollam (178), Wayanad (174), and Thiruvananthapuram (169).  The lowest number of legumes was found in Eranakulam District (69 taxa).

 

Endemic and threatened legumes

Among the 361 indigenous legumes found in Kerala, 81 are endemic to India and 33 are confined to the Western Ghats-Sri Lanka biodiversity hotspot.  Out of 81 Indian endemic species legumes, 32 are restricted to the Western Ghats of Kerala, Karnataka, and Tamil Nadu states.  About 17 taxa, namely Crotalaria assamica var. keralensis, Dalbergia beddomei, D. travancorica, Dialium travancoricum, Humboldtia bourdillonii, H. brunonis var. raktapushpa, H. sanjappae, H. unijuga var. trijuga, Kunstleria keralensis, Millettia pulchra var. munnarensis, Phanera murthyi, Sanjappa cynometroides, Smithia venkobarowii var. venkobarowii, S. venkobarowii var. glabra, Tephrosia travancorica, T. wynaadensis, and Vigna sathishiana are endemic to Kerala.  The distribution range of 81 Indian endemic legumes found in Kerala is analysed and represented in Fig. 4.  Among the threatened legumes found in Kerala, Dialium travancoricum and H. unijuga var. trijuga are Critically Endangered, Cynometra travancorica, Humboldtia bourdillonii, H. unijuga var. unijuga, H. vahliana, Kingiodendron pinnatum, and Sophora wightii are Endangered and Saraca asoca is Vulnerable (IUCN 2020).  Cynometra beddomei, which is treated as Extinct in the Red List, has been re-collected recently (Sasidharan 1998), and hence it can be categorised as Critically Endangered.  During our field studies Dialium travancoricum is found to be the most threatened tree species in Kerala and is on the brink of extinction due to poor regeneration.  This species is survived with a few numbers of very old trees in Ponmudi forest ranges of Thiruvananthapuram District.  Among Endangered tree legumes, Kingiodendron pinnatum is facing severe threats due to over-exploitation and habitat destruction.  The oleo-gum-resin of this plant species is used in gonorrhoea, catarrhal conditions of genito-urinary and respiratory tract (Kumar et al. 2011), and also in the paint industry.  The species has been severely exploited for its wood oil in the past and the stem bark is collected as a substitute for Saraca asoca.  Dalbergia travancorica is another highly threatened legume restricted to a few lowland urban sacred groves in Thiruvananthapuram (Jagadeesan et al. 2015).

 

Economically important legumes

Arachis hypogea (Groundnut), Cajanus cajan (Red Gram), Canavalia gladiata (Sword Bean), Cicer arietinum (Bengal Gram), Cyamopsis tetragonoloba (Cluster Bean), Lablab purpureus (Lablab Bean), Phaseolus coccineus (Scarlet Runner), P. lunatus (Lima Bean), P. vulgaris (French Bean), Psophocarpus tetragonolobus (Winged Bean), Sesbania sesban (Swamp Pea), Vigna mungo (Black Gram), Vigna radiata (Green Gram), V. unguiculata ssp. cylindrica (Catjang), and V. unguiculata ssp. unguiculata (Cowpea) are commonly cultivated in the state for pulses/vegetables.  Pisum sativum (Garden Pea) is cultivated in high ranges in Idukki District.  Dalbergia latifolia (Malabar Rosewood), D. lanceolaria, D. sissoo, and Pterocarpus marsupium (Kino), and P. santalinus (Red Sandalwood) are known for their quality timber.  About one-third of the legumes in Kerala have known medicinal properties (Kirtikar & Basu 1918; Ambasta 1986; Parrota 2001).  These include Abrus precatorius, Butea monosperma, Clitoria ternatea, Codariocalyx motorius, Cullen corylifolia, Indigofera tinctoria, Kingiodendron pinnatum, Mucuna pruriens, Pongamia pinnata, Pseudarthria viscida, and Saraca asoca.  Centrosema molle, Desmodium intortum, Leucaena leucocephala, Macrotyloma uniflorum, Sesbania sesban, Stylosanthes guianensis, and S. hamata are the forage legumes found in the state.  Calopogonium mucunoides, Mucuna bracteata, and Pueraria phaseoloides are grown as cover crops in rubber plantations.

 

Ornamental legumes

Amherstia nobilis, Arachis glabrata, A. pintoi, Brownea coccinea, B. grandiceps, Bauhinia spp., Caesalpinia pulcherrima, Cassia spp., Clitoria ternatea, and Senna spp. are widely grown in Kerala for ornamental purposes.  Albizia saman, Castanospermum australe, Cassia javanica, Delonix elata, D. regia, Libidibia coriaria, Millettia peguensis, Parkia biglandulosa, and Peltophorum pterocarpum are the common avenue trees in the state.

 

Invasive legumes

Exotic legumes like Centrosema molle, Mimosa diplotricha, Senna hirsuta, S. occidentalis, S. sophera, S. tora, among others have extensively invaded the degraded forest areas and open wastelands throughout the state and are causing severe threat to the native flora.  Several forage legumes introduded have escaped from farms and have become invasive in the plains especially by the road-sides during the last two decades.  Desmodium scorpiurus, D. tortuosum, Stylosanthes guianensis, and S. hamata have become a serious threat to indigenous plants in the plains.  Desmodium intortum and D. uncinatum are emerging as rapidly multiplying weeds in the high ranges in Idukki District.  Senna uniflora is a recently reported weed in the plains of central Kerala.

 

Excluded legumes

Five legumes previously reported from the state of Kerala (Saidharan 2004; Nayar et al. 2006) have been excluded in this checklist due to the various reasons given below:

1. Desmodium caudatum (Thunb.) DC.: reported from Malappuram District (Sivarajan & Mathew 1997) based on Philip Mathew 33038 (CALI) was a misidentification of Sohmaea laxiflora (DC.) H.Ohashi & K.Ohashi

2. Humboldtia laurifolia Vahl: Robert Wight’s collection of ‘H. laurifolia from ‘Malabar’ region of India 180 years ago was found to be a misidentification of H. vahliana Wight (Balan et al. 2016).

3. Indigofera barberi Gamble: No specimens or record of collection from Kerala found.

4. Rhynchosia rothii Benth. ex Aitch.: Reported from Silent valley National Park in Palakkad District (Manilal 1988) based on T. Sabu 10897 (CALI) was a misidentification of Neonotonia wightii (Arn.) J.A.Lackey.

5. Vigna bourneae Gamble: No specimens or record of collection from Kerala found.

 

Notes

Sibichen & Nampy (2007) described Crotalaria kurisumalayana, a taxon closely allied to C. multiflora Benth. from the Vagamon Hills of central Kerala.  C. multiflora is an Indo-Sri Lankan species distributed in the grasslands and open hill slopes of higher elevations.  The authors distinguished C. kurisumalayana from C. multiflora, mainly based on the shape of leaves, lax racemes, and sericeous ferruginous pods.  Since these characters are highly overlapping, Krishnaraj & Mohanan (2012) reduced C. kurisumalayana to a variety of C. multiflora and identified the presence or absence of purple striations as the main distinguishing characters.  Field studies, however, revealed that this purple striation is also not consistent and therefore the trinomial is reduced to a synonym of C. multiflora.

 

For figures & images - - click here

 

 

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