PLANTS: Annuals or perennial herbs, rarely low shrubs. STEMS: terete or 4-angled. LEAVES: opposite with connecting fimbriate stipules. INFLORESCENCE: 1-several flowers in axillary glomerules. FLOWERS: small; calyx 2-4 dentate; corolla funnelform, 4-lobed; stamens 4. FRUIT: 2 nutlets, the calyx teeth persistent. NOTES: Ca. 50 spp. mostly of warmer parts of Amer., a few in Afr. (Greek: diodos = a thoroughfare, because often found growing by the wayside). REFERENCES: Dempster, Lauramay T. 1995. Rubiaceae. J. Ariz. - Nev. Sci. 29(l): 29.