PLANT: Suffrutescent. LEAVES: alternate. FLOWERS: showy, solitary or paired in the upper leaf-axils; corolla salverform; stamens included in the corolla tube, the anthers not connivent. FOLLICLES: terete. SEEDS: comose. NOTES: 3 spp. in sw U.S., Mex, Cuba (Greek: haplo = single + phyton = plant). The plant contains alkaloids that are insecticidal to cockroaches, flies, fleas, lice and mosquitoes. REFERENCES: McLaughlin, Steven, P. 1994. Apocynaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 164-168.