Commelinaceae Mirb.

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://creativecommons.org/licenses/by/3.0

Morphology General Habit

Annual or perennial herbs, generally terrestrial and somewhat fleshy or succulent, when perennial with rhizomes or stolons; stems clearly divided into nodes and internodes, simple or branched, sometimes rooting from the stem; roots fibrous, fine or tuberous

Morphology Leaves

Leaves simple, alternate, distichous or spiral, sometimes as basal rosettes, generally sessile, petiolate, if present then not inflated; sheath closed, glabrous, villose to densely hairy, margin generally ciliate

Morphology Reproductive morphology Inflorescences

Inflorescence terminal and/or axillary or basal, with few to many unilateral cymes aggregated in thyrses, flowers subtended by foliaceous bracts or enveloped by spathaceous bracts

Morphology Reproductive morphology Flowers

Flowers hermaphroditic, sometimes hermaphroditic and male, rarely cleistogamous, trimerous with radial or bilateral symmetry; perianth separated into sepals and petals, sepals 3 free, imbricate; petals 3, usually free, often disintegrating easily; stamens 6 in two series, sometimes 1-4, modified into staminodes or suppressed in some genera, filaments free or epipetalous, frequently hairy, anthers basifixed or dorsifixed, sometimes versatile, with longitudinal or poricidal dehiscence; ovary superior, (2-)3-locular, placentation axile, ovules 1 to many per locule, septal nectaries absent, style simple, stigma punctiform or capitate, rarely penicillate

Morphology Reproductive morphology Fruits

Fruits loculicidal capsules, 2-3- valvate, rarely indehiscent, baccaceous and sometimes crowned by fleshy sepals; seeds normally without aril, hilum linear to punctual, embryo covered by a callous tissue (embryotegium), testa smooth or ornamented.

Note

Notes on delimitation: Molecular studies have shown that Commelinaceae are included in the order Commelinales together with Haemodoraceae, Hanguanaceae, Philydraceae and Pontederiaceae (APG II, 2003), with the Pontederiaceae as the nearest family to Commelinaceae.

Distribution

Aneilema R.Br. (Panama, Peru and Brazil, c. 2 species).  Buforrestia C.B.Clarke (tropical South America, c. 3 species). Callisia Loefl. (tropical America, c. 20 species). Cochliostema Lem. (Nicaragua to Ecuador, 2 species). Commelina L. (Over 40 species in tropical America). Dichorisandra J.C.Mikan (tropical America, mainly in Brazil, c. 65 species). Elasis D.R.Hunt (Ecuador, 1 species). Floscopa Lour. (tropical America, c. 2 species). Geogenanthus Ule (tropical South America, 5 species). Gibasis Raf. (México to Argentina, c. 11 species). Gibasoides D.R.Hunt (Mexico, 16 species). Matudanthus D.R.Hunt (Mexico, 1 species). Murdannia Royle (Introduced to the Neotropics where it has c. 3 species). Plowmanianthus Faden & C.R.Hardy (Panama, Peru and Brazil, 5 species). Pollia Thunb. (Panama, 1 species). Siderasis Raf. (tropical South America, c. 3 species). Thyrsanthemum Pichon (Mexico, 3 species). Tinantia Scheidw. (Mexico to Argentina, 13 species). Tradescantia L. (Over 60 species in tropical America). Tripogandra Raf. (tropical America, c. 22 species). Weldenia Schult.f. (Mexico to Guatemala, 1 species). Most genera cited here are native to the Neotropics. Only Murdannia has species introduced from the Old World. Species of Dichorisandra, Tradescantia and Gibasis geniculata (Jacq.) Rohweder are used as ornamentals. Several species of Commelina are weedy.

Diagnostic

Distinguishing characters (always present): Leaves with closed sheaths that may be involute in bud. Leaves alternate, distichously or spirally arranged, sometimes in basal rosettes. Inflorescences terminal and also axillary or basal, with unilateral cymes. Sepals and petals 3, clearly distinguishable, petals sometimes disintegrating. Usually fleshy or succulent herbs. The filaments are often conspicuously hairy. Faden and Hunt (1991) accepted 2 subfamilies: Cartonematoideae (raphide canals absent or next to the leaf veins), which was divided into 2 tribes: Cartonemateae and Tricerateleeae; and Commelinoideae (raphide canals present and mostly between leaf veins, etc), also comprising 2 tribes: Tradescantieae and Commelineae. To identify the genera it is important to observe flower characters in the field, e.g.the colour and shape of the petals, and the number of stamens, their disposition and the dehiscence of the anthers. The plant habit is also important and may vary between rosulate, rhizomatous or stoloniferous, trailing plants, and erect or semi-scandent herbs to 4 m tall. Key differences from similar families: Differs from: Pontederiaceae, which are aquatic and floating or immersed and have inflated petioles. Haemodoraceae, where perianth whorls are fused basally and septal nectaries are present. Notable genera and distinguishing features: Dichorisandra: Anther dehiscence always poricidal, but functionally poricidal anthers with an introrse longitudinal slit are also found.

Timothy Utteridge & Gemma Bramley (2020). The Kew Tropical Plant Families Identification Handbook, Second Edition. Kew Publishing Royal Botanic Gardens, Kew

Note

Herbs, often with rather succulent leaves or stems. Leaves with a closed basal sheath, often longitudinally striped or ridged, lacking a ligule. At least inner tepals rapidly deliquescent (in a few hours), filaments often hairy.

Recognition

Characters of similar families: Poaceae: stems with nodes, leaves ligulate, flowers reduced, in bract-rich inflorescences. Zingiberaceae: leaves ligulate, petiole not pulvinate, petals large and showy, persistent, aromatic rhizome.

Morphology General Habit

Herbs often with rather succulent cauline leaves or stems

Morphology Roots

Roots fibrous or tuberous, nodes swollen

Morphology General Hair

Hairs often present, at least on leaf sheaths

Morphology Leaves

Leaves with a basal sheath, often longitudinally striped or ridged, lacking a ligule, often pseudopetiolate, lamina simple, entire

Morphology Reproductive morphology Inflorescences

Inflorescences usually a panicle-like thyrse comprising several to many helicoid, cymose branches, sometimes with a spathaceous bract

Morphology Reproductive morphology Flowers Calyx

Tepals in 2 whorls, outer 3 sepaloid or petaloid, inner 3 petaloid, white or coloured, at least inner whorl deliquescent, filaments often hairy

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary superior, 2- or 3-locular

Morphology Reproductive morphology Fruits

Fruit usually a dehiscent capsule, rarely indehiscent or a berry.

Distribution

About 41 genera and 650 species, most of which are tropical.

Ecology

Mainly in moist or mesic forests or grassland, but also in arid areas. Some Floscopa species are aquatic.

Description Author

Paul Wilkin

Commelinaceae, Robert Faden. Flora of Tropical East Africa. 2012

Distribution

Range: Well-represented in Africa and Madagascar. East Africa has more species of Commelinaceae than any other regional flora or country flora worldwide.

George R. Proctor (2012). Flora of the Cayman Isands (Second Edition). Royal Botanic Gardens, Kew

Morphology General Habit

Annual or perennial herbs, often rather succulent, with alternate entire leaves, these usually with sheathing or clasping bases.

Morphology Reproductive morphology Flowers

Flowers perfect, regular or irregular, in cymes or umbels usually subtended by spathe-like or leafy bracts

Morphology Reproductive morphology Flowers Calyx

Sepals 3, free and distinct, usually green and herbaceous

Morphology Reproductive morphology Flowers Corolla

Petals usually 3, delicate and soon withering, free or united into a tube

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens typically 6, in 2 whorls of 3 each, but in some genera dimorphic or reduced in number; anthers 2-celled

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary superior, 2- or 3-celled; ovules 1 to several in each cell; sometimes only 1 or 2 cells fertile

Morphology Reproductive morphology Fruits

Fruit a 2- or 3-valved capsule, or indehiscent.

Distribution

A tropical and warm-temperate family of about 30 genera and 650 species.