Spermacoce hyssopifolia Willd. ex R. & S., Syst. Veg. 3: 532. 1818; H.B.K. Nov. Gen. & Sp. 3: 268. 1819.
Spermacoce linearis Willd. ex R. & S., Syst. Veg. 3: 532. 1818; H.B.K. Nov. Gen. & Sp. 3: 343. 1819.
Diodia articulata Pohl ex DC., Prodr. 4: 564. 1830.
Diodia surinamensis Miq., Stirp. Sur. 180. 1850.
Diodia hyssopifolia manifests several types of variations which affect the following characters: leaf width, length, and pubescence, stipular sheath pubescence, stem pubescence, length of internode and branching of stem, length of calyx lobes, and fruit size and pubescence. Upon such differences a number of taxa have been described. It is difficult to draw arbitrary lines to separate the extremes of variation exhibited by D. hyssopifolia, and the varieties and forms here recognized must be considered as belonging to the same variable taxon.