PLANTS: Low, suffrutescent plants. LEAVES: opposite, sessile or short-petiolate. FLOWERS: axillary; corolla funnelform; stamens included in the corolla tube, the anthers connivent and cohering to the large stigma. SEEDS: comose. NOTES: 10 spp. in N. Amer. and S. Amer. (Latin: macro = long + sipho = tube). Woodson, R. E., Jr. 1933. Ann. Missouri Bot. Gard. 20:605-790. REFERENCES: McLaughlin, Steven, P. 1994. Apocynaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 164-168.
