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FNA | Family List | FNA Vol. 22 | Commelinaceae

6. Commelina Plumier ex Linnaeus, Sp. Pl. 1: 40. 1753; Gen. Pl. ed.; 5:25, 1754.

Dayflower, widow's-tears [for the two Dutch botanists Jan and Kaspar Commelijn, because of the two showy petals]

Herbs, perennial or annual. Roots thin or tuberous. Leaves 2-ranked or spirally arranged, not glaucous; blade sessile or petiolate. Inflorescences terminal, leaf-opposed; cymes 1--2, enclosed in spathes, proximal cyme several-flowered, distal cyme vestigial or with 1--several staminate flowers; spathes often filled with mucilaginous liquid, margins distinct or basally connate; bracteoles usually absent. Flowers bisexual and staminate, bilaterally symmetric; pedicels well developed; sepals distinct or proximal 2 connate, unequal; petals distinct, proximal petal often different color than distal 2, smaller or subequal, distal 2 blue (occasionally lilac, lavender, yellow, peach, apricot, or white), clawed; stamens (5--)6, proximal 3 fertile, medial different in form, size from others, distal (2--)3 staminodial; filaments glabrous; antherodes commonly 4--6-lobed; ovary 2--3-locular, ovules 1--2 per locule, 1-seriate. Capsules 2--3-valved, 2--3-locular. Seeds 1--2 per locule; hilum linear; embryotega lateral. x = 11--15.

Species ca. 170 (9 in the flora): almost worldwide, mainly tropical.


Brashier, C. K. 1966. A revision of Commelina (Plum.) L. in the U.S.A. Bull. Torrey Bot. Club 93: 1--19. Faden, R. B. 1993b. The misconstrued and rare species of Commelina (Commelinaceae) in the eastern United States. Ann. Missouri Bot. Gard. 80: 208--218. Pennell, F. W. 1916. Notes on plants of the southern United States—I. Bull. Torrey Bot. Club 43: 96--111.

1 Spathes with margins distinct to base.   (2)
+ Spathes with margins connate basally.   (5)
2 (1) Perennials with erect to ascending stems; roots tuberous; leaves linear to linear-lanceolate   1 Commelina dianthifolia
+ Annuals or perennials usually with decumbent to scandent stems; leaves narrowly lanceolate to ovate-elliptic.   (3)
3 (2) Spathes generally whitish or pale green toward peduncle with contrasting, dark green veins; proximal petal white or paler than others; capsules 2-locular; seeds rugose pitted-reticulate   2 Commelina communis
+ Spathes without contrasting veins; proximal petal ± concolorous with others; capsules 3-locular; seeds reticulate or smooth to faintly alveolate.   (4)
4 (3) Spathes not at all to slightly falcate; distal cyme usually vestigial (rarely well developed, 1-flowered); seeds smooth to faintly alveolate   3 Commelina caroliniana
+ Spathes usually distinctly falcate; distal cyme in larger spathes usually well developed, 1--several-flowered; seeds reticulate   4 Commelina diffusa
5 (1) Flowers apricot- or peach-colored   5 Commelina gambiae
+ Flowers blue (rarely lilac to lavender or white).   (6)
6 (5) Leaf sheaths with auricles at summit; roots stout; proximal petal white, minute; locules all 1-seeded   6 Commelina erecta
+ Leaf sheaths not auriculate; roots thin; proximal petal blue to lilac or lavender, conspicuous; some locules usually 2-seeded.   (7)
7 (6) Perennials with erect to ascending stems; leaf sheaths with red hairs at summit; leaf blades 6--20 cm; spathes 1.5--3.5 cm; subterranean, cleistogamous flowers absent   7 Commelina virginica
+ Annuals or perennials with ascending to decumbent, repent or scrambling stems; sheaths with or without red hairs at summit; leaf blades 1.5--7(--9) cm; spathes 0.5--2 cm; subterranean, cleistogamous flowers sometimes present.   (8)
8 (7) Leaf blades ovate to lanceolate-elliptic; sheaths often with red hairs at summit; lateral stamen filaments not winged; capsules usually 5-seeded   8 Commelina benghalensis
+ Leaf blades oblong to lanceolate-oblong or oblong-elliptic; sheaths without red hairs; lateral stamen filaments winged; capsules usually 1-seeded   9 Commelina forskaolii

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