in moist forests, such as the rainforests in Queensland. Adaptation Epiphytes are not adapted to droughts in the same way are other flora, because they don’t have access to the ground, but they still have some mechanisms to help them survive. Some become completely dormant for months at a time; many epiphytes show crassulacean acid metabolism (CAM), which involves taking in CO2 at night, and photo-fixing it during the day with closed stomata to reduce water loss by transpiration. They also contain absorptive plants that are capable at quickly taking up water when it is available and preventing drought when water is scarcer. CAM can be impeded by higher night-time temperatures, dehydrated tissues, and high saturation deficits in the surrounding air, which lower the "stomata conductance" of the epiphytes, reducing the CO2 uptake, which in turn reduces growth and reproduction and even induces carbon loss. Higher temperatures, strain on evaporation, and contact to light cause CAM-idling, which is the epiphyte closing its stomata when it becomes stressed, that brings down the range of habitats a species can inhabit. Epiphyte species work biomasses are much more sensitive to different relative moisture levels than other plants. Tribe classification The subfamily Epidendroideae is divided into two clades or subgroups known as the higher epidendroids (vandoids) and the lower epidendroids. The lower epidendroids contain polyphyletic tribes, particularly the Arethuseae and Epidendreae. The tribes are listed below: This classification has a rather ephemeral nature and is prone to frequent revision. Changes are likely to occur as new morphological and genetic data become available. References External links A phylogenetic analysis of the Orchidaceae - evidence from rbcL nucleotide sequences Orchid Tree: a phylogeny of epiphytes on the tree of life Asparagales subfamilies