Abstract: The present study contains the census of endemic flowering plants of Kerala state, India. A total of 344 endemic taxa belong to 175 genera of 65 families are compiled and presented. The distribution and reference to each taxon are provided. Analysis of the families revealed that Poaceae (50) has the highest number of endemic species followed by Rubiaceae (37) and Orchidaceae (24).
INTRODUCTION
The word endemic is ascribed to any taxon, which has a restricted distribution. Endemics are commonly categorized in four contexts of spatial distribution, (1) site or restricted area, (2) biotope, (3) biogeographical region and (4) political area. India is rich ecologically, biologically and culturally; in biodiversity it is one of the richest in the world being one among the twelve mega-biodiversity countries of the world.
Kerala is considered as one of the most biologically rich state on the tropical Malabar Coast of South Western India. It falls under the Malabar (Western Ghats) region of the nine biogeographic regions of India. Flora of Kerala shows striking similarity with many countries of the Middle East, Central Asia, China and East Africa besides Australia and America. Study of Endemism within the Kerala state has been attempted in past. The first attempt to prepare a list of endemic plants of Kerala was made by Ahmedullah and Nayar (1986) who estimated 132 species. Singh and Subramanyan (1991) enumerated 108 species as endemic to Kerala. Manilal and Raveendrakumar (1998) reviewed the floristic studies in Kerala. According to Mohanan and Nair (1999) there are over 4000 species are found in the state (the source of this estimate is unknown) and they provided a list of 165 endemic taxa, which is also not very exhaustive.
In view of incomplete information and underestimation of endemic plants of Kerala, an attempt of preparation of detailed census of endemic plants was done, based on field studies, taxonomic literature and herbarium collections deposited at Central National Herbarium (CNH), Howrah (CAL), Botanical Survey of India (BSI) Herbarium, Coimbatore (MH) and Kerala Forest Research Institute, Trivandum (KFRI). The present study brings to light as many as 344 endemic flowering plants of Kerala state.
Study Area
Several field studies were undertaken in Kerala state during Western Ghat
Biodiversity project (1999-2003). Kerala is one of the smallest Indian States
lies on the south-west corner of the Peninsula between 8° 18' and 12°
48' N latitude and 74° 54' and 77° 12' E longitude. It is bounded Tamil
Nadu and Karnataka on the east and northeast, Indian Ocean and islands of Lakshadeep
on south and west, respectively. Kerala is one of four states that comprise
the linguistic-cultural region known as South India. The total area is 38, 863
sq km, which is only about 1.8% of the total geographical area of India. Kerala’s
coast runs for some 580 km, while state itself varies between 35 to 120 km in
width. It lies near the center of Indian tectonic plate, as such most of the
state is subject to comparatively little seismic and volcanic activity. Geographically,
Pre-Cambrian and Pleistocene formations comprise the bulk of Kerala’s terrain.
The total forest area is 15.577 km2, which is about 40% of total
geographical area of the state.
Administratively, Kerala has 14 districts: Alappuzha, Ernakulam, Idukki, Kannur, Kasaragod, Kollam, Kottayam, Kozhikode, Malappuram, Palakkad, Pathanamthitta, Kasaragod, Kollam, Kottayam, Kozhikode, Malappuram, Palakkad, Pathanamthitta, Thiruvananthapuram, Thrissur and Waynad. Kerala enjoys a moderately warm-humid tropical climate with very little variation in temperature. The four main seasons are winter (Jan.-Feb.), summer (March-May), south-west monsoon (June-Sept.) and north-east monsoon (Aug.-Dec.). The average annual rainfall in the state varies from 1016 to 7620 mm. The forests of the state are classified into wet evergreen, semi-evergreen, moist deciduous, dry deciduous and thorn forest types. Besides, there are estuarine vegetation, Grasslands and fresh water swamps (Myristica swamp) and other seral types spread over limited areas. Major of the portion of the forest area is under Western Ghats, which is one of the known hotspot of the world.
Enumeration
Information about the endemic flowering plant taxa is presented family and
genus-wise alphabetically (Table 1). The IUCN threatened category
(E: Endangered; V: Vulnerable; R: Rare; I:Indeterminate) is also given in parenthesis
after plant name. Additional information such as distribution of the taxon in
the state and the reference number to the concerned publication are provided.
| Table 1: | List of endemic flowering plants of Kerala |
| *IUCN threat category (R: Rare; V: Vulnerable; E: Endangered; I: Indeterminate) | |
RESULTS AND DISCUSSION
Kerala harbours significant biodiversity, most of which is concentrated in the east. The present study records 344 endemic taxa pertaining to 175 genera of 65 families of flowering plants. Out of 65 families, dicots are having 56 families and monocots with 9 families. Kerala is represented with seven endemic genera, Kanjarum (Acanthaceae), Haplothismia (Burmanniaceae), Chandrasekharania, Limnopoa and Silentvalleya (Poaceae), Seidenfadeniella (Orchidaceae) and Janakia (Periplocaceae). The district-wise analysis shows that Palakkad with 55 reports tops the list, followed by Idukki with 49 and Thiruvananthapuram with 31. The large number of new reports (endemics) from the above districts may be due to more botanical explorations. It is observed that high concentration of endemism is found in Silent Valley (Palakkad dist.) with 38 taxa, followed by Agasthyamala (12), Devicolam (11), Peerumedu (10) and Eravikulam (9). The maximum number of endemic taxa belongs to Poaceae (50) followed by Rubiaceae (37), Orchidaceae (24) and Araceae (17). Of the estimated 175 genera of endemic taxa Ischaemum is dominant with 18 species followed by Impatiens (16), Fimbristylis (11), Dimeria (10), Hedyotis (10), Sonerila (9), Curcuma (8), Arisaema (7), Syzygium (7) and Vernonia (7). A total of 50 species are found in IUCN threatened category (Nayar and Sastry, 1987; 1988; 1990). Out of those threatened species, 5 species are rare, 4 are vulnerable, 16 are endangered and 25 are indeterminate category.
ACKNOWLEDGMENTS
Authors are thankful to Dr. M. Sanjappa, Director, BSI, Calcutta, Dr. P. Daniel, Deputy Director (Retd.), BSI, Southern Circle, Coimbatore, Dr. N. Sasidharan, Scientist, KFRI, Peechi and Dr. P.V. Sreekumar, Head, BSI andaman and Nicobar Circle for permission and facilities to work in the Herbarium and Library. The first author is grateful to Dr. M.S.R. Murthy, Head, Forestry and Ecology Division, National Remote Sensing Agency (NRSA), Hyderabad for encouragement and suggestions.