Monographs Details: Sipanea trichantha Miq.
Authority: Maguire, Bassett. 1967. The botany of the Guayana Highland--Part VII. Mem. New York Bot. Gard. 17: 1-439.
Family:Rubiaceae
Scientific Name:Sipanea trichantha Miq.
Discussion:

described from Suriname, is conspecific with S. dichotoma H.B.K. The photo of the type of S. trichantha (Hostmann 663 from the Delessert Herb.) shows loosely moderately villous stems with elongated leaves with a short, appressed pilosity on the lower nerves and midrib. The lower surface appears glabrate, while the upper surface appears appressed-pilose with short hairs. The photo shows elongate, setaceous calyx-lobes which appear to measure 3.5-4.5 mm long. The corolla-lobes in bud appear to show slight pilosity along the outer margins. The characters shown by the photo of the S. trichantha type fall within the range of variation matched by various other collections from Suriname with similarly elongated leaves, similar type of inflorescence, calyx-lobes, and corolla-tube, which are to be identified with S. dichotoma H.B.K. (= S. pratensis var dichotoma), tending toward the variation with longer, slender, calyx-lobes.

A study of the type specimen of Sipanea colombiana Wernh. from the British Museum shows that it is likewise conspecific with the range of variation displayed within the S. dichotoma complex.

The specimen, Dawe 445, from Baja Magdalena, Colombia, was collected just west of Ocana, the type locality of Sipanea colombiana. It has the basal exterior portion of the corolla-tube glabrous but the rest of the tube is sparsely to moderately puberulous without. Wernham described the tube of the corolla as “extus fere glabrae.” While the type specimen shows the exterior of the corolla-tube to be glabrous, the corolla limb is sparsely puberulous with short, loose, ascending hairs on the lower exterior portion and glabrous in the upper exterior part. In the other specimens examined from Colombia and cited above, the upper part of the corolla-tube varies from sparsely pilose to moderately pilose without. The dense villosity on stems, leaves, calyx, and hypanthium encountered in the specimen of Cuatrecasas 3567 indicates some introgression with S. hispida, another species found in this section of Colombia. Likewise, the very densely villous stems of Barriga 8466 suggest similar introgression.