Two new additions and one confirmation of the occurrence of Lamiaceae (Lamiales) species from Northern dry zone in Sri Lanka

Abstract

Sri Lanka abounds with a rich plant diversity, comprising 3087 species of flowering plants, of which 863 are endemic to the island. In Sri Lanka, the Lamiaceae plant family represents 70 indigenous species in 22 genera, distributed throughout the country in varied habitats. Since many of the species of the family are herbaceous and seasonal, less attention had been paid in field collections during the past. Here we document Leucas diffusa Benth. and Orthosiphon pallidus Royle ex. Benth. for the first time in Sri Lanka and further we confirm the existence of Endostemon viscosus (Roth) M.R. Ashby, a species that was included doubtfully in Sri Lankan flora, with field collected specimens. Each of these species is presented with a detailed taxonomic description, its ecology, places of occurrence in Sri Lanka, field photographs, and other relevant notes. All of these species were reported from the Northern dry zone of Sri Lanka, an area that was not accessible for botanists for 30 years due to civil war. This area has highly seasonal, rich herbaceous vegetation during the North Eastern monsoonal period. These findings, made during just two years, highlight that botanical explorations conducted in a timely manner in these seasonal habitats will reveal more undocumented herbaceous species.