Cuticles of Vascular Epiphytes: Efficient Barriers for Water Loss after Stomatal Closure?

Water permeabilities of astomatous, isolated cuticular membranes of 15 vascular epiphyte species ( families: Araceae, Orchidaceae and Piperaceae) from the moist lowland forest of Barro Colorado Nature Monument, Panama, were investigated. Permeances determined at 308C ranged from 0 . 46 10 6 m s 1 (Aspasia principissa (Rchb. f.) R.E. Schult.) to 6 . 07 10 6 m s 1 (Polystachya foliosa (Hook.) Rchb. f.). Comparison of these data with permeances of plants from other habitats corroborates the notion that cuticular properties reect the climatic demands of the growing sites. The studied group of vascular epiphytes, living in a very drought-prone habitat, showed the lowest cuticular permeances to water recorded to date.