About Oldenlandiopsis callitrichoides (Griseb.) Terrell & W.H.Lewis
Oldenlandiopsis, commonly called creeping-bluet, is a monospecific genus of flowering plants in the family Rubiaceae, meaning it contains only one species: Oldenlandiopsis callitrichoides. This species was previously classified under either the genus Hedyotis or the genus Oldenlandia. The genus Oldenlandiopsis was established in 1990 by Edward E. Terrell and Walter H. Lewis. The generic name refers to this genus's similarity to the genus Oldenlandia. The specific epithet callitrichoides refers to the species's superficial resemblance to Callitriche, a genus in the family Plantaginaceae. Oldenlandiopsis callitrichoides was first formally described in 1862 by August Grisebach as Oldenlandia callitrichoides, in a pre-print of a paper that was published the following year in Memoirs of the American Academy of Arts and Sciences. Oldenlandiopsis callitrichoides is native to the West Indies, southern Mexico, and Central America, and has become naturalized in other regions including Florida, Hawaii, South America, and tropical Africa. Oldenlandiopsis is a member of the tribe Spermacoceae. Within this tribe, it is not particularly closely related to Oldenlandia, contrary to prior classification beliefs. It is very closely related to Houstonia, and may be Houstonia's sister taxon.
