Acianthus caudatus

Flowering plant 6–14 cm tall. Leaf cordate to ovate, thin, 7–33 mm long, 7–30 mm wide, green above, reddish-purple beneath, margins bluntly toothed, sometimes minutely. Flowers 1–6, dark purplish, often with musty odour; pedicel (including ovary) 4–10 mm long, subtended by small bract; dorsal sepal more or less inflexed, 20–45 mm long, base concave, dilating narrowly above column, then tapering to long fine point; lateral sepals much shorter than dorsal sepal, 12–25 mm long, tapering to fine points curving upwards at tips; petals reflexed or spreading, curved-lanceolate, relatively short, c. 5 mm long. Labellum recurved or curved downwards in upper part, sessile, elongate-ovate to triangular, 4–6 mm long, c. 3 mm wide; base erect, embracing column, tip deflexed; margins entire; callus with 2 erect basal glands and a narrow longitudinal channel. Column with very narrow wings on underside of almost terete lower two-thirds. Flowers Aug.–Oct.