This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Erect ascending or procumbent, somewhat succulent, branching herbs, with short-peti-oled or sessile leaves, and irregular mostly blue flowers in sessile cymes subtended by spathe-like bracts. Sepals somewhat unequal, the larger ones sometimes slightly united. Petals blue, unequal, 2 of them larger than the third. Perfect stamens 3, rarely 2, one of them incurved and its anther commonly larger. Sterile stamens usually 3, smaller, their anthers various. Filaments all glabrous. Capsule 2-3-cclled. Seeds 1 or 2 in each cavity, the testa firm, roughened, smooth or reticulated. [Dedicated to Kaspar Commelin, 1667-1731, Dutch botanist.]
About 95 species of wide distribution in warm and temperate regions. Besides the following, some 3 others occur in the southern United States. Type species: Commelina communis L. Snathes not united at the base.
Spathes acuminate; capsules 3-celled, 5-seeded.
Spathes acute; capsules 2-celled, 4-seeded.
Spathes with united bases.
All three cavities of the ovary with 2 ovules.
Sheaths, at least the lower ones, glabrous or nearly so; pubescence, if present, not hirsute.
Sheaths more or less hirsute.
Capsules 2-valved, dorsal cavity indehiscent.
Capsules 3-valved, all cavities dehiscent.
Ventral cavities of the ovary with 2 ovules, dorsal cavity with 1 ovule.
(ihbrous or very nearly so throughout, stems procumbent or creeping, rooting at the nodes, 1°-2 1/2° long. Leaves lanceolate or ovate-lanceolate, 1-3' long, 4"-8" wide, acute or acuminate at the apex, their sheaths sometimes ciliate; spathe acute or acuminate, 8"-12" long, peduncled, the 2 bracts not united by their margins; flowers few in each spathe, 3"-6" broad; ventral cells of the ovary 2-ovuled, the dorsal 1-ovuled; capsule commonly 5-seeded (2 seeds in each of the ventral cells, 1 in the dorsal); seeds oblong, reticulated, about 1" long.
Along streams and in waste places, New Jersey to Indiana, Missouri, Florida, Texas and through tropical America to Paraguay. Widely distributed in Asia and Africa. July-Oct.