Octarrhena


Octarrhena, commonly known as grub orchids, is a genus of flowering plants from the orchid family, Orchidaceae. Plants in this genus are small, orchids with short stems, thin roots, short, thick, fleshy leaves arranged in two ranks and tiny flowers. The labellum is rigidly attached to the base of the column. There are about fifty species native to areas from Sri Lanka and Malesia to the Western Pacific.

Description

Orchids in the genus Octarrhena are small epiphytic, lithophytic or terrestrial herbs with thin roots and short stems with short, thick, fleshy leaves, their bases sheathing the stem. A large number of tiny, usually white, cream-coloured, yellowish or greenish flowers are arranged on a flowering stem arising from a leaf axil. The sepals and petals are free from each other, the petals usually much smaller than the sepals. The labellum is small, unlobed, rigidly fixed to the column and lacks a spur.

Taxonomy and naming

The genus Octarrhena was first formally described in 1861 by George Henry Kendrick Thwaites who published the description in Enumeratio plantarum Zeylaniae. The name Octarrhena is derived from the Ancient Greek words okto meaning "eight" and arrhen meaning "male" or "masculine", referring the eight free pollinia in the anther.

Species list

The following is a list of species of Octarrhena recognised by the World Checklist of Selected Plant Families as at January 2019:
Orchids in the genus Octarrhena are found in Sri Lanka, Vietnam, Borneo, Java, Peninsular Malaysia, the Philippines, Sulawesi, Sumatra, the Bismarck Archipelago, New Guinea, the Solomon Islands, Queensland , Fiji, New Caledonia, Vanuatu and the Caroline Islands.