PLANTS: Small shrubs (rarely perennial herbs). LEAVES: simple, sometimes whorled, the stipules subulate. FLOWERS: in terminal cymes, perfect; calyx 4-lobed, the lobes persistent; corolla long-tubular or salverform, with 4 spreading lobes; stamens 4, attached in tube or throat; styles included or exserted; stigmas 2. FRUIT: a 2-loculed loculicidal capsule. NOTES: ca. 50 spp. From AZ, NM, and TX through Mex. and C. Amer. to n S. Amer. (for Charles Bouvard). REFERENCES: Dempster, Lauramay T. 1995. Rubiaceae. J. Ariz. - Nev. Sci. 29(l): 29.