Citation: Nees, in Wallich, Pl. Asiat. Rar. 3:81 (1832).

Derivation: Greek di, two; pteron, wing; 2-winged acanthus, referring to the two large leafy bracteoles enclosing the base of the corolla tube.

Synonymy: Ruellia sensu Benth., Fl. Aust. 4:545 (1868) partly.

Common name: None

Description:
Herbs or shrubs with cystoliths; branches 4-angled; leaves petiolate, ovate, the opposite pairs connected by a transverse ridge across the node, graduating into bracts.

Flowers 1 or 2 (rarely 3), sessile in the upper axils and combined into a terminal raceme, large and showy or inconspicuous and cleistogamous, subtended at their base by 2 leafy bracteoles exceeding the calyx; calyx segments 5, equal, linear; corolla more or less regular, tubular at the base and widening into the throat, 5-lobed; lobes equal, contorted in bud, spreading in flower, basally with longitudinal folds forming palate-like projections; stamens 4, in pairs of unequal length, inserted at the top of the Corolla tube, included (in S. Aust.) and held against the upper surface of the corolla, sometimes accompanied by a single staminode; filaments connected in pairs by a basal membrane; anther cells 2, parallel, inserted at the same level, glabrous, without basal appendages; disk annular with an irregular rim; ovary with 4-8 ovules per cell; style longer than the stamens; stigma with 1 lobe flattened and much larger than the other.

Capsule narrow and seedless at the base, expanded and seed-bearing apically, 1-16-seeded; seed with only the thickened rim possessing mucilaginous hairs which expand on wetting.

Distribution:  About 20-30 species in Africa, India and Malesia. In Australia there are 2 species, 1 of which extends into S. Aust.

Biology: No text

Taxonomic notes: Dipteracanthus is a segregate of the very widely spread genus Ruellia (c. 250 species world wide) and opinions vary as to its status. It has been maintained here at the generic level in line with the circumscription usually adopted in this region.

Author: Not yet available