Herbs, perennial, unbranched to usually sparsely branched. Roots tuberous. Stems erect to ascending. Leaves: blade linear to linear-lanceolate, 4--15 ´ 0.4--1 cm, apex acuminate, glabrous to puberulent. Inflorescences: distal cyme usually 1-flowered, exserted; spathes solitary, green, often suffused and/or striped with purple, pedunculate, falcate or not, 2.5--8 ´ 0.7--1.7 cm, margins distinct, scabrous, not ciliate, apex acuminate, glabrous to puberulent; peduncles 1.5--9.5 cm. Flowers bisexual and staminate; pedicels puberulent; petals dark blue, proximal petal somewhat smaller; staminodes 3; antherodes yellow, cruciform. Capsules 3-locular, 2-valved, 5--6 mm, apiculate. Seeds 5, brown, 2.2--2.7 ´ 1.7--2.2 mm, rugose, pitted. Flowering summer--fall. Rocky soils; Ariz., Colo., N.Mex., Tex.; Mexico. Two varieties have been recognized: Commelina dianthifolia var. dianthifolia (Arizona, New Mexico, Texas), with the spathes gradually tapering into a long, acuminate apex, and C. dianthifolia var. longispatha (Torrey) Brashier (Arizona, Colorado, New Mexico), with the spathes abruptly narrowed below the middle into a long, attentuate tip (C. K. Brashier 1966). Although most U.S. specimens are readily separable into these taxa, their ranges and ecologies overlap very broadly in Arizona and New Mexico. Until their variation in Mexico is studied, I can see no useful purpose in maintaining these varieties.

Plant: Perennial herb; tuberous roots; STEMS erect to ascending, unbranched to sparsely branched Leaves: sheaths with purple veins, blade linear-lanceolate, 4-15 cm long, 0.4-1 cm wide, glabrous to puberulous, the margin scabrous, the apex acuminate INFLORESCENCE: solitary spathes, peduncles 1.5-9.5 cm long, spathes 2.5-8 cm long, 0.7-1.7 cm wide, the margins free, scabrous, the surface green, often suffused and/or striped with purple, glabrous to puberulous, the apex acuminate; upper cyme usually 1-flowered Flowers: perfect or staminate; pedicels puberulous; petals dark blue, the lower ones ±not clawed; staminodes 3, yellow, cruciform Fruit: FRUITS 5-6 mm long, apiculate. SEEDS 5, brown, 2-2.5 mm long, 1.5-2 mm wide, rugose, pitted; SEEDS 1-5, testa rugose or smooth, tan to brown, hilum linear Misc: Open grassy meadows in ponderosa pine, oak and pinyon-juniper forest on granitic substrate; 1200-2900 m (4000-9500 ft.); Jul-Sep REFERENCES: Puente, Raul, and Robert B. Faden. 2001. Commelinaceae. J. Ariz. – Nev. Acad. Sci. Volume 33(1).