Terrestrial, usually glabrous herbs with oblong or ovoid tubers. Leaf solitary, chanelled or terete, more or less succulent, linear-acuminate, or more rarely expanded at the base and constricted above. Peduncle often tall with several foliaceous bracts. Floral bracts acute or acuminate, rarely foliaceous. Flowers ranging from white through red and yellow to blue and purple. 1–40 in a lax terminal raceme. Perianth almost regular, the labellum differing only slightly from the sepals and sepaloid petals. Column in two parts—(i) a central portion with the 2-celled stigma and rostellum on one face, and having the other face concave to support the protruding anther-cells; and (ii) a posterior portion consisting of two filaments confluent with the column-wings and carrying the rostrate anther-connective and the pendent 2-celled anther. Column-wings prominent and extremely variable, showing two main lines of development—(i) 2 primary lateral lobes, large, more or less erect, usually simple, rarely fimbriate, with a variable crest of small calli in the sinus; (ii) primary lobes confluent to form

Thelymitra sanscilia Irwin. Column, showing from left to right: side, half front, rear and top.