Commelina L.

Sp.Pl. 2:40 (1753)
Name Status

Scientific Description

Family Commelinaceae.

Habit and leaf form. Herbs; evergreen. Plants non-succulent. Annual, or perennial; plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves (?). Young stems cylindrical, or oval in section (? often prominently ribbed); often breaking easily at the nodes. Self supporting (or creeping). Mesophytic, or helophytic, or hydrophytic (rarely). Leaves alternate; spiral, or distichous (?); fleshy, or ‘herbaceous’ (?); petiolate, or sessile (?); sheathing. Leaf sheaths with joined margins. Leaves simple. Leaf blades entire; linear to ovate; parallel-veined. Leaves eligulate. Leaf blade margins entire. Vernation involute, or plicate (?). Vegetative anatomy. Plants with silica bodies, or without silica bodies (?). Leaf anatomy. Leaf blade epidermis without differentiation into ‘long’ and ‘short’ cells. Guard-cells not ‘grass type’. Hairs present, or absent; glandular hairs absent. Stem anatomy. Secondary thickening absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries absent (nectaries lacking). Autogamous or entomophilous (but without nectar). Pollination mechanism conspicuously specialized (with dimorphic stamens comprising concolourous fertilizing members, and specialised, bright yellow ‘food stamens’ attractive to pollinators but producing little pollen).

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes. The terminal inflorescence unit cymose. Inflorescences terminal, or axillary; pedunculate; without involucral bracts; spatheate (a spathe or somewhat spathe-like leaf subtending each cyme or pair of cymes; spathes folded or obliquely funnel-shaped, with the flowers exserted consecutively). Flowers very irregular. The floral asymmetry involving the perianth and involving the androecium. Flowers cyclic. Perigone tube absent. Perianth with distinct calyx and corolla; 6; 2 -whorled; isomerous; free, or joined; sepaloid and petaloid; different in the two whorls; blue, or violet, or white. Calyx 3; 1 -whorled; polysepalous, or partially gamosepalous (then lateral segments connate, adaxial segments free); regular; green. Corolla 3; 1 -whorled; polypetalous, or partially gamopetalous (rarely 2 segments connate); unequal but not bilabiate (the adaxial petal usually reduced); blue to violet, or white (rarely). Petals when polypetalous, clawed, or sessile (?). Androecium (5–)6. Androecial members free of the perianth; free of one another; 2 -whorled. Androecium including staminodes. Staminodes (2–)3 (adaxial); with cross-shaped anthers. Stamens 3 (on abaxial side of flower); isomerous with the perianth. Filaments glabrous. Anthers dorsifixed, or basifixed (?); versatile, or non-versatile (?); dehiscing via longitudinal slits; appendaged, or unappendaged (?). Gynoecium 3 carpelled. The pistil 2–3 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; superior. Ovary plurilocular; 2–3 locular (sometimes abaxial locule undeveloped). The ‘odd’ carpel (where ascertainable) anterior (?). Styles 1; apical. Stigmas wet type, or dry type (?); papillate, or non-papillate (?); Group II type, Group III type, and Group IV type (?). Placentation axile. Ovules 1–2 per locule; ascending; arillate; orthotropous to hemianatropous (?).

Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Fruit 2–3 locular. Seeds ellipsoid or compressed on one side; copiously endospermic. Endosperm not oily (mealy). Seeds with starch. Cotyledons 1, or 2 (? the second sometimes present, vestigial). Testa operculate (in the form of a characteristic callosity, the ‘embryostega’, covering the embryo); smooth or reticulate to rugose. Seedling. Hypocotyl internode present, or absent (?). Seedling collar conspicuous, or not conspicuous (?). Cotyledon hyperphyll elongated, or compact (?). Coleoptile present, or absent (?). First leaf dorsiventral. Primary root ephemeral.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C3.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, Northern Territory, Queensland, and New South Wales. Northern Botanical Province and Eremaean Botanical Province.

H.R. Coleman, 8 September 2016

Taxonomic Literature

  • Wheeler, J. R.; Rye, B. L.; Koch, B. L.; Wilson, A. J. G.; Western Australian Herbarium (1992). Flora of the Kimberley region. Western Australian Herbarium. Como, W.A.