Decumbent to erect, to 6 dm, usually conspicuously hairy, with oblong or lance-oblong lvs 1-4 cm and the fls numerous in dense, axillary and terminal, often peduncled clusters, is widespread in trop. and warm-temp. regions, including s. U.S., but only rarely adventive and probably not persistent with us.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.