Guilleminea densa (Willd.) Moq.

Guilleminea densa var. densa has been reported from several U. S. states (e.g., J. T. Kartesz and C. A. Meacham 1999). J. Henrickson (1987) implicitly rejected those records, stating that the variety "as considered here is widespread in South America, naturalized in southern Africa, and Queensland, Australia, but does not occur in North America."

Illecebrum densum Humboldt & Bonpland ex Schultes in J. J. Roemer et al., Syst. Veg. 5: 517. 1819; Brayulinea densa (Willdenow ex Roemer & Schultes) Small

densa: dense

A woolly, prostrate mat-forming perennial herb. Leaves narrowly elliptic to broadly ovate; glabrous on the upper surface and with long matted white hairs on the lower surface. Inflorescences to 6 mm, dense, ovoid, whitish.

Frequent

Native of the warmer parts of N and S America, from the southern USA to northern Argentina, and now a widespread tropical weed

Brayulinea densa (Wilid.) Small, Fl. SE. U. S. 394. 1903
Illecebrum densum Willd.; R. & S. Syst. Veg. 5: 517. 1819.
Guilleminea illecebroides H. B. K. Nov. Gen. & Sp. 6: 42. 1823.
Guilleminea Illecebrum Spreng. Syst. 4: Cur. Post. 103. 1827.
Guilleminea densa Moq. in DC. Prodr. 13 2 : 338. 1849.
Achyranthes conferta Pavon; Moq. in DC. Prodr. 13 2 : 338, as synonym. 1849.
Guilleminea densa aggregata Uline & Bray, Bot. Gaz. 20: 343. 1895.
Stems numerous from a. thick vertical root, much branched, prostrate, 5-25 cm. long, stout, densely lanate; basal leaves evanescent or wanting, long-p etiolate, the blades oblanceolate or obovate, obtuse or acutish; cauline leaves short-petiolate, the petioles winged, the blades elliptic to broadly oval, asymmetric, 3-15 mm. long, 1.5-9 mm. wide, obtuse or acute at the apex, abruptly narrowed at the base, green and glabrous on the upper surface or sparsely villous when young, densely villous or lanate beneath; flowers densely glomerate, the glomerules much shorter than the leaves ; bracts ovate, acute, scarious, white, glabrous ; bractlets oblongovate, obtuse; calyx 2-2.5 mm. long, slightly longer than the bractlets, the tube densely lanate, the lobes lance-ovate, acutish, glabrous, scarious, white; utricle glabrous; seed compressedovoid, 0.6 mm. long, brown, shining.
Type locality: Tropical America.
Distribution: In dry, stony soil, western Texas to southern Arizona, and southward to southern Mexico; also from Brazil to Argentina and Bolivia,

Guilleminea densa là loài thực vật có hoa thuộc họ Dền. Loài này được (Willd. ex Schult.) Moq. mô tả khoa học đầu tiên năm 1849.