Monographs Details: Diodia hyssopifolia var. hyssopifolia f. hyssopifolia
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Rubiaceae
Discussion:

Diodia hyssopifolia (Willd. ex R. & S.) Cham. & Schl., Linnaea 3: 350. 1828.

Spermacoce hyssopifolia Willd. ex R. & S., Syst. Veg. 3: 432. 1818; H.B.K. Nov. Gen. & Sp. 3: 268. 1819.

Spermacoce hyssopifolia was based on a Venezuelan collection by Humboldt and Bonpland from San Borja along the Orinoco River in Estado Bolívar just north of the border of that state with Territory Federal Amazonas. Collections cited above near the type locality are Wurdack & Monachino 39751 and Velez 2338. Both these collection show much branched, crowded and shortened internodes between the verticils of flowers, linear, strongly 1-nerved leaf blades, often only 1-1.5 (-2) long but up to 3-5 cm long, and usually quite narrow (1-2 mm broad in material near the type locality), but as broad as 2.5-3 mm. The calyx lobes are ovate-triangular or ovate-lanceolate and inconspicuous, varying from 0.2-1.2 × 0.3-0.5 or more mm. The leaf blades vary from glabrate beneath to rather densely pubescent. The stems vary from densely puberulent or hirtello-puberulous more or less on all sides to nearly glabrous, or with lines of puberulence running between the stipular bases. The corollas are generally 3-3.5 mm long, and the small seeds are 2-3 mm long.