While there are no leafless species of Aerangis known, there are related species in other genera of the sub-tribe Aerangidinae
Most orchids are epiphytic though they can also be terrestrial, lithophytic,
and/or mycoparasitic. One of the most extreme examples of reduction in the epiphytic
habit can be found within the specialized tribe Vandeae, which contains many reduced
"leafless" species. In these orchids, photosynthetic leaves are absent or reduced
and deciduous, contributing no net carbon gain to the plant. Instead, the roots
have assumed the role of food-assimilation using a CAM-like system of recycling
CO2 (Benzing & Ott, 1981). This represents a possible adaptation for nutrient
economy in humid forest canopy environments. These reduced, monopodial orchids have
been referred to as "shootless" by other workers (Benzing et al., 1983; Cockburn
et al., 1985), although they do possess a reduced stem system. Benzing and Ott (1981)
also suggested these extreme epiphytes have evolutionarily reduced their carbon
investment in vegetative organs by limiting shoot formation while allocating more
energy for flower and fruit production.
Under the most widely accepted classification system
based primarily on floral morphology (Dressler, 1993), there are 13 genera that
include approximately 202
leafless species
distributed in the three subtribes of Vandeae: Angraecinae, Aerangidinae, and Aeridinae.
Barbara Carlsward's Research