Herbs annual or perennial, sometimes woody at base. Stems with prominent nodes and internodes. Leaves alternate, distichous or spirally arranged, sessile or petiolate; leaf sheath prominent, open or closed; leaf blade simple, entire. Inflorescence usually of cincinni in panicles or solitary, sometimes shortened into heads, sometimes sessile with flowers fascicled, sometimes axillary and penetrating enveloping leaf sheath, rarely flowers solitary and terminal or axillary. Flowers bisexual, rarely unisexual, actinomorphic or zygomorphic. Sepals 3, free or connate only at base, often boat-shaped or carinate, sometimes galeate at apex. Petals (2 or)3, free, sometimes connate and tubular at middle and free at 2 ends ( Cyanotis), sometimes clawed. Stamens 6, free, all or only 2 or 3 fertile; filaments glabrous or torulose villous; anthers parallel or slightly divergent, longitudinally dehiscent, rarely dehiscent by apical pores; staminodes 1--3; antherodes 4-lobed and butterflylike, 3-sect, 2-lobed and dumbbell-shaped, or entire. Ovary 3-loculed, or reduced to 2-loculed; ovules 1 to several per locule, orthotropous. Fruit a loculicidal, 2- or 3-valved capsule, rarely baccate and indehiscent. Seeds few, large; endosperm copious; hilum orbicular or linear.
Herbs, perennial or annual. Leaves basal or cauline, alternate; sheaths closed; blade simple, often succulent, margins entire, venation parallel. Inflorescences terminal or terminal and axillary [sometimes all axillary], sometimes becoming leaf-opposed, cymose (cymes scorpioid), thyrsiform or variously reduced, sometimes umbel-like, sometimes enclosed in spathaceous bracts. Flowers bisexual or bisexual and staminate on same plants, rarely bisexual and pistillate on same plants [bisexual and unisexual (staminate and pistillate), all on same plants], bilaterally or radially symmetric; sepals 3, sepaloid [occasionally petaloid], distinct or occasionally connate, usually subequal; petals 3, deliquescent, petaloid, distinct or connate, equal or unequal; stamens 6, all fertile or some staminodial or absent (rarely all stamens absent); anthers with longitudinal [rarely poricidal] dehiscence; ovary superior, 2--3-locular; ovules 1-seriate [2-seriate]; style 1, simple, usually slender; stigma 1, simple [rarely slightly 3-lobed], enlarged or not. Fruits loculicidal capsules [rarely indehiscent or berries]. Seeds 1--several [rarely many] per locule; hilum dotlike or linear; lidlike embryotega covering embryo.
Ovary superior, 2-3-locular, with a simple terminal style and a small more or less capitate stigma; ovules 1-6 (-10) per loculus, axile
Fruit usually a loculicidal capsule, sometimes partly or wholly indehiscent, or (in Palisota) a berry
Seeds usually crowded, with the contiguous faces flat, often muricate, ridged or reticulate, relatively large; the testa characteristically marked on the outside with a circular or elliptic callosity called the embryostega (or embryotega), under which the embryo is situated; hilum punctiform or linear; endosperm abundant, mealy
Perennial or annual herbs, often more or less succulent, mostly terrestrial, sometimes aquatic, frequently producing adventitious roots at the nodes; stems erect to prostrate, rarely somewhat climbing
Leaves alternate (falsely whorled in Palisota), with a basal membranous often nervose and closed sheath
Inflorescence composed of single or aggregated cincinni, terminal, lateral or axillary; sometimes each cincinnus may be reduced to single or (apparently) fascicled flowers
Sepals 3, free, usually green or membranous
Flowers actinomorphic or zygomorphic, often surrounded by mucilage
Stamens hypogynous, basically 6 in two whorls, but variously modified or suppressed; fertile stamens 2, 3 or 6; staminodes 0, 3 (or rarely 4); filaments (with us) free, glabrous or with moniliform hairs; anthers dorsifixed or basifixed, 2-locular, dehiscing by longitudinal slits (or by basal pores in Cyanotis)
Faden, R. B. 1998. Commelinaceae. In: K. Kubitzki et al., eds. 1990+. The Families and Genera of Vascular Plants. 4+ vols. Berlin etc. Vol. 4, pp. 109--128. Faden, R. B. and D. R. Hunt. 1991. The classification of the Commelinaceae. Taxon 40: 19--31. Hunt, D. R. 1975. The reunion of Setcreasea and Separotheca with Tradescantia. American Commelinaceae: I. Kew Bull. 30: 443--458. Hunt, D. R. 1986. Campelia, Rhoeo and Zebrina united with Tradescantia. American Commelinaceae: XIII. Kew Bull. 41: 401--405. Hunt, D. R. 1986b. Amplification of Callisia Loefl. American Commelinaceae: XV. Kew Bull. 41: 407--412. Tucker, G. C. 1989. The genera of Commelinaceae in the southeastern United States. J. Arnold Arbor. 70: 97--130.