The sub-family Vanilloideae belongs to the family Orchidaceae.
It consists of 2 tribes with 15 genera and about 180 species.
They are mainly known for the species that produce vanilla.
They are herbaceous, perennial plants which grow epiphytic as vines.
Some species are epi-parasitic and leafless, but usually there are green, fleshy or leathery leaves, implanted in spiral or two rows. The veins are often net-like, unlike most orchids that have parallel nerved leaves.
The inflorescence is an unbranched cluster. The flowers are resupinate so that the lip is at the bottom. The sepals and petals are tri-lobed.
The pestle and a remaining fertile stamen are fused into a slim gynostemium. The pollen grains are mealy, slightly sticky and sometimes transformed into pollinia.
The fruit is usually a fleshy capsule that opens along cracks. It contains numerous lentil-like seeds, 0.5-1 mm wide, with a hard seed coat.
They are found in all tropical regions, throughout Asia, Australia and South America.