Description: Annual or perennial herbs; stems prostrate to erect.
Leaves with sheath usually ciliate at mouth; lamina glabrous, sessile or shortly petiolate.
Inflorescence axillary, arising from within a conduplicate or funnel-shaped spathe; flowers few, pedicellate, in 1 or 2 short cymes, the upper one, when present, mostly 1-flowered and male. Outer tepals often unequal, membranous, free or the lower 2 fused; inner tepals unequal, free, the upper 2 petaloid, blue, yellow or white, the lower one reduced, often colourless. Fertile stamens usually 3, filaments slender, glabrous, anthers oblong, dehiscing by slits; staminodes 3, rarely 2, variable in shape. Ovary 3- or sometimes 2-locular; ovules 1 or 2 per loculus, occasionally lacking in the dorsal loculus.
Fruit a dry capsule; seeds greyish to dark brown or black, smooth or ornamented.
Distribution and occurrence: World: c. 170 species, cosmopolitan. Australia: c. 10 species (2 species naturalized), Qld, N.S.W., S.A., W.A., N.T.
Text by Peter G. Wilson
Taxon concept:
| | Key to the species | |
| 1 | Flowers blue | 2 |
| Flowers yellow | Commelina africana |
| 2 | Spathes conduplicate; base cordate, not fused | Commelina cyanea |
| Spathes funnel-shaped; base fused
Back to 1 | 3 |
| 3 | Leaves lanceolate to linear, acuminate | Commelina ensifolia |
| Leaves ovate to elliptic, obtuse or acute
Back to 2 | Commelina benghalensis |
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