Vegetative key to the families

EPIPHYTES on trees or rocks

Leaves with parallel venation, or terete. Pseudobulbs and aerial roots with velamen often present (Fig. 41) Orchidaceae

Plants terrestrial with tubers or rhizomes. Leaves basal and/or cauline, large or scale-like

Autotrophs with green leaves and stems; stems sometimes coloured. Leaves sometimes absent at flowering time

Leaves 1 or none or leaves absent at flowering time. Stem-bracts present or absent

Leaves hairy. Labellum without hairs, or with calli

Leaves glabrous, or absent at flowering time