Anatomy of Some Terete-Leaved Orchid Species

Abstract

Leaf anatomy was investigated in six epiphytic orchid species in five genera—Cleisostoma filiforme (Lindl.) Garay, Eria pannea Lindl., Oberonia oklongensis Chowlu et al., Papilionanthe teres (Roxb.) Schltr, Papilionanthe vandarum (Rchb. f.) Garay and Schoenorchis gemmata (Lindl.) J. J. Smith. The aim of the study was to determine if these species exhibited any visible special xeromorphic characters. Freehand transverse section and peeling techniques were used. Most species had a thick cuticle with a cuticular ledge and were amphistomatic. However, cuticular papillae were present only in O. oklongensis, P. vandarum and S. gemmata. Specialised water-storage cells were present within the mesophyll tissue in all the species except E. pannea. Both xylem and phloem found in S. gemmata consisted of fibrous caps. Raphide bundles were present abundantly in the mesophyll and epidermal cells of E. pannea and O. oklongensis. Sphaeraphides were present in the epidermal cells along with stomata of P. teres. Guard cells were cuticularized in almost all species except E. pannea. Wax-secreting cells were observed in E. pannea and O. oklongensis. Paracytic stomata were found in C. filiforme, E. pannea, P. teres, P. vandarum and S. gemmata. Only O. oklongensis possessed actinocytic stomata.