A TAXONOMIC REVISION OF EXACUM L. (GENTIANACEAE - EXACEAE) IN SOUTH INDIA.

The paleotropic genus Exacum (Gentianaceae: Exaceae) is revised for South India, recognizing twelve species and one variety. E. wightianum var. uniflorum is synonymized under E. klackenbergii while E. grande is reduced to the variety of E. tetragonum. Nine out of thirteen taxa (75%) are endemic to the southern Western Ghats while one is critically endangered (E. travancoricum), one endangered (E. tetragonum), one vulnerable (E. courtallense) and six are rare (E. anamallayanum, E. atropurpureum, E. klackenbergii, E. lawii, E. tetragonum var. grande and E. wightianum). The problems in the typification of E. courtallense var. laxiflorum are dicussed. Detailed taxonomic descriptions, photoplates and a key to the identification of species in South India are provided.