There are groups of between two and six erect, flattened stems each with up to six leaves that have a ridged lower surface.

This orchid is found from Thailand to the southwest Pacific.Thelasis carinata is an epiphytic or lithophytic herb with thin roots and flattened stems 20–50 mm (0.79–2.0 in) long in groups of between two and six.

The flowers are self-pollinating, tube-shaped near their bases and have an ovary that is triangular in cross section.

[2][3][4] Thelasis carinata was first formally described in 1825 by Carl Ludwig Blume who published the description in Bijdragen tot de flora van Nederlandsch Indië.

[7] The triangular fly orchid usually grows on rocks and trees in humid, well-lit situations.