Flowering Plant Diversity in Sri Lanka, with special reference to Endemism and Nomenclature

Pradeep Rajatewa

Sri Lanka has considerably high diversity of flowering plants. According to the recent checklist published in 2001, in Sri Lanka there are 214 flowering plant families, 1,522 genera and 4,143 species. Of the total number of species, about 75% are indigenous and about 25% are exotic. Of the total number of indigenous plant species 27.53% are found to be endemic to Sri Lanka. 75% of Flowering plants belong to the sub class - Dicoteledonae and rest belongs to the sub class - Monocoteledonae. Above mentioned numbers and percentages can vary slightly, due to the incompletion of the checklist. There are enough evidences to suggest the total number of flowering plant of Sri Lanka may exceed 4,500. In this it is study considered that there are 4206 plant species in Sri Lanka for further analysis.

Sri Lanka has the 871 endemic flowering plant species and 827 of them do not have lower taxa, but 44 species have. It includes 2 forma (1 sp), 26 sub species (13 sp) and 60 verities (30 sp). Apart from that, 15 subspecies (14 sp.), 46 verities (31 sp) and 2 forma (1 sp) are endemic to Sri Lanka. Within this 871 endemic species more than 12 point endemics included. Available literature is not enough to reveal all the point endemics. It is believe that Sri Lanka has 17 endemic genera. On recent study shows 3 of them are not endemic genera. It is difficult to find the endemism of another two genera because there generic name has been changed.

Nomenclature of the plants of Sri Lanka started from the period of eminent taxonomist Carols Linnaeus in 17 th century. But till today there are no any analysis have been made of the nomenclature. This study is attempted to fill this gap. According to this study 1612 plant names were changed. It includes 315 introduced plants and 248 endemic plants. Carols Linnaeus was the leading taxonomist who describes the highest number of flora that find in Sri Lanka. There are 542 species. But it includes very few endemics. Thwaitesi has described the highest numbers of endemic species. His total descriptions is 298 and 240 of them are endemic. Alston and Henry Trimen were the other taxonomists who described over 50 species. Only 6 Sri Lankan authors were able to describe the plant species (22 sp.). D.M.A. Jayaweera is the leading person among them who described 9 species.

There are only 2490 specific epithets used for 4206 plant species. zeylanica is the most commonly used specific epithet. It used for 72 times. Another 11 epithets that related to the epithet zeylanica has used 74 times (synonyms for Sri Lanka). indica and thwatesii are the next mostly used epithets. Another 25 epithets have Sri Lankan origin. It includes 7 Sinhala names that use for the related plants, 12 places or the area name that find the relevant plant species and 6 epithets mentioned the eminent taxonomist or the people’s name that have Sri Lankan origin.