Taxonomic study of family Linderniaceaf Borsch Kai Mull. and E.B. fisch in Nepal

Abstract

Linderniaceae, false Pimpernel family is recognized as a distinct family based upon recent molecular evidences. The family, which is represented by its type genus Lindernia All., comprises 20 genera and about 314 species distributed worldwide in moist tropical, subtropical and temperate zones of both the Old and New Worlds. The taxon is distinctive mainly in being herbs with simple and opposite leaves; zygomorphic flowers; winged or unwinged calyx; geniculate, swollen or appendaged anterior stamens; disc around ovary and bilipped ciliated stigma. There was a lack of comprehensive account of Nepalese Linderniaceae based on fresh collections. Enumeration accounts of Nepalese Linderniaceae were based on herbarium specimens deposited at national and world herbaria, but still they had some problems regarding identification, nomenclature of the taxa and their distribution. This study resolved the taxonomic problems of the family, on the basis of comprehensive morphological study of fresh collections and the herbarium specimens. The collection of the specimens was done during flowering seasons of the taxa in different regions of Nepal. The herbarium preparation was done by following standard guidelines. A detailed description of each taxon was prepared after identification, and morphological study of the specimens along with distribution, illustration, field photographs and cluster analysis. This study describes 20 species of Linderniaceae in Nepal under six genera (Bonnaya: 5 species, Craterostigma: 1 species, Lindernia; 2 species, Torenia: 8 species, Vandellia: 2 species and Yamazakia: 2 species). Taxa mainly differ in shape, size, colour and texture of stem; leaf shape and venation; pedicel texture; calyx shape; corolla colour and texture; stamens; ovary shape and texture; and capsule shape. Lindernia spp. are delimited from other genera by palmately veined leaves over pinnately veined leaves. Bonnaya spp. are delimited by the presence of two fertile stamens and anterior staminodes. Torenia spp. are distinguished by their winged clayx, mainly appendaged anterior stamens and apically pubescent ovary. Vandellia spp. and Yamazakia spp. are delimited by their glandular pedicel and clayx. Nomenclature is updated based on recent molecular studies.

The species distribution has shown a great variation in horizontal or vertical geographic regions. Among 20 species, 11 species are distributed in West (W), Central (C) and Eastern (E) Nepal, six species are reported only from Central and Eastern Nepal. Similarly, two species are found to be restricted in only Central Nepal. Furthermore, taxonomy of three species namely Craterostigma sessiliflorum, Torenia cordata and T. hookeri is discussed thoroughly and suggested to research further. Presente study excludes C. nummularifolia because of confusion.