Herbs, rarely undershrubs. Leaves alternate, scattered or densely imbricate, entire; stipules wanting. Flowers hermaphrodite or unisexual, irregular or almost regular. Calyx adnate to the ovary; lobes usually 5, free or connate into two lips. Corolla gamopetalous, 5-lobed; the lobes subregular and equal in the New Zealand genera, but in the bulk of the order the lowest lobe is smaller and narrower and recurved, and is known as the labellum. Stamens 2; filaments united with the style into a column; anthers sessile at the top of the column. Ovary inferior, more or less completely 2-celled, usually crowned with 1 or 2 fleshy glands. Stigma at the apex of the column, entire or 2-lobed, hidden between the anthers or protruding from between them. Ovules numerous in each cell, attached to the dissepiment or to a central axis, anatropous. Fruit a 1–2-celled capsule, dehiscent or indehiscent. Seeds numerous or few by abortion, minute; albumen fleshy; embryo very minute, next the hilum.

A small order, comprising 5 genera and about 110 species, mainly confined to Australia, 97 species being endemic therein. Of the 3 New Zealand genera, Oreostylidium is endemic; Phyllachne extends to antarctic South America; while Forstera has a single species in Tasmania in addition to the 3 New Zealand ones.