Thrixspermum Lour.

Abstract

Thrixspermum is a genus of around 100 monopodial; epiphytic orchid species are distributed in Thailand, Peninsular Malaysia, Sumatra, Borneo and Java, with the maximum number of species (29) in Peninsular Malaysia. Plants are tall and climbing, or short, creeping along braches or growing on shrubs. Leaves are flat, bilobed and coriaceous. Inflorescence is axillary, bearing ephemeral flowers that open 1 - 2 at a time, often lasting only half a day (Fig. 111.1). Thereafter, the inflorescence continues to elongate slowly and initiates flower buds which remain dormant until they are triggered by a sudden drop in ambient temperature. Flowering is then gregarious. The rainy season in Southeast Asia where Thrixspermum is native lasts for 6 months, and it is during this season that maximum lowering of temperature occurs during a nocturnal thunderstorm Four species are described and illustrated.