Comparative anatomical and stomatal studies of some taxa of group vandoideae

The paper presents anatomical features of the aerial root, stem, leaf and stoma of three species of Acampe rigida Roxb., Rhynchostylis retusa (Linn.) Blume and Vanda tessellate (Roxb.) Hook belonging to the tribe Vandeae including the subtribe Aeridinae. The prominent characters of the epiphytes were 4 to 5 layers of velamen cells, uniseriate exodermis with U-thickened cell walls and collateral vascular bundles in roots. The raphide bundles occurred in roots and leaves. Endodermal cells are O and U-thickened. Sunken stomata with anisocytic, paracytic and stomatal chambers were observed. The vascular bundles in leaves occurred in single series with alternating large and small bundles. The leaf, root, stem and floral elements showed amphystomatic, homogenous mesophyll with aerial spaces.