Cuticles of vascular epiphytes: Efficient barriers for water loss after stomatal closure?

Water permeabilities of astomatous, isolated cuticular membranes of 15 vasc ular epiphyte species (families: Araceae, Orchidaceae and Piperaceae) from the moist lowland forest of Barro Colorado Nature Monument, Panama, were in vestigated. Permeances determined at 30 degrees C ranged from 0.46 x 10(-6) m s(-1) (Aspasia principissa (Rchb. f.) R.E. Schult.) to 6.07 x 10(-6) m s (-1) (Polystachya foliosa (Hook.) Rchb. f). Comparison of these data with p ermeances of plants from other habitats corroborates the notion that cuticu lar properties reflect the climatic demands of the growing sites. The studi ed group of vascular epiphytes, living in a very drought-prone habitat, sho wed the lowest cuticular permeances to water recorded to date. (C) 2000 Ann als of Botany Company.