Endemic Impatiens (Balsaminaceae) of Western Ghats

Owing to the most congenial climatic conditions, Western Ghats are endowed with rich assemblage of diverse plant species including many endemic taxa and qualifies as the only Indian center, among the five distinct diversity hotspots of the genus Impatiens L. The genus Impatiens consists of about 1000 species, distributed in the tropical and subtropical regions of the Old world as well as in the northern temperate regions. In India there are about 215 species of Impatiens recorded so far, of which 142 species are endemic and about 106 species occur in Western Ghats. The diversity occurs in two regions viz., the Eastern Himalayas and the Western Ghats.

The richness of flowering plants makes India one of the mega diversity countries in the world with four biodiversity hotspots and three mega centres of endemism. The flora of India shows high diversity in terms of families, genera and species of angiosperms. Many genera and families are known to be represented by a large number of endemic species, one amongst them is the genus Impatiens of the family Balsaminaceae. The family Balsaminaceae comprises annual as well as perennial herbs, undershrubs and shrubs that show salient floral morphology. It comprises two widespread genera viz., Hydrocera Wight & Arn., a monotypic genus and Impatiens L., a genus with a large number of species. Hydrocera can be distinguished by its five free petals and capsular berry, while Impatiens has four petals that are fused to form two lateral petals and a 5-valved capsule. Hydrocera triflora (L.) Wight & Arn. is a semi-aquatic herb distributed in the Indomalesian region.

Many species of Impatiens L. are cultivated as ornamental and some are used in medicine and cosmetic. Species of this genus are commonly known as ‘Balsams’ or ‘Jewel Weeds’. The effective pollinators of most Impatiens species are honeybees, while the flowers are also visited by butterflies, aphids, stingless bees and beetles which aid pollination in absence of honeybees. Some species of Sect. Annuae are self-pollinated.