Sp. Pl. 1: 271. 1753.
Fla., La., s Mexico, West Indies, Central America, introduced also in tropical Asia, Africa, Madagascar, Indian Ocean Islands, Pacific Islands, Australia.
Varieties 2 (1 in the flora).
Both varieties of Turnera ulmifolia are homostylous with var. acuta (Sprengel) Urban occurring in Bermuda and the West Indies. Both are used as medicinal plants in the West Indies.
I. Urban (1883) described 12 varieties in Turnera ulmifolia. Experimental studies have demonstrated that this species as he circumscribed it is a polyploid complex in which most of the taxa deserve species status (M. M. Arbo and Aveliano Fernández 1987; Fernández 1997; Fernández and Arbo 2000; J. S. Shore and S. C. H. Barrett 1985; V. G. Solís Neffa and Fernández 2000).