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.'

Plant: Perennial prostrate mat-forming forb; stems numerous from a thick root Leaves: leaves opposite, ovate, the pair unequal, woolly beneath, basal in rosettes, 10-40 mm, oblong-lanceolate, early deciduous; cauline petiole 1-6 mm, blade 2-16 mm, elliptic to round, acute to obtuse, glabrous or sparsely silky above, long-soft-hairy below; cauline leaves smaller, clustered in axils INFLORESCENCE: clusters of spikes, axillary, < or = 4 mm wide, subtended by and mixed with reduced leaves; bracts 1.5-2.5 mm, glabrous, white-scarious Flowers: flowers in dense axillary glomerules; calyx 1.5-2.8 mm, lobes reflexed, erect in age, tip acute to rounded, midvein ending before tip; filament tube 0.1-0.2 mm, free filaments 0.1-0.3 mm Fruit: indehiscent capsule; wall membranous; Seed lenticular to spheric, smooth, ± 0.8 mm, red-brown Misc: Disturbed places; < 100 m.