Herbaceous flowering plants of the genus Cuphea (Lythraceae) are noted for synthesizing significant amounts of medium-chain caprylic, capric, lauric, and myristic fatty acids (FAs) in the seed oils, with each species typically emphasizing one of several FAs. The genus is a prospective temperate source of oilseeds for fatty acids used in the manufacture of products as diverse as soaps, food, and biofuels, and it has become a model research system for the study of enzyme-mediated fatty acid synthesis. Seed oil FA composition for 44 species is reported here, including first records for 25 species from South America, primarily from Brazil. Nineteen species are re-analyzed to verify earlier results and expand information on variability in oil composition. An appendix summarizes seed oil composition of 108