Type. Ad fluvium Orinoco, Venezuela, Bonpland.
I have seen only a photograph of the type from the Berlin Herbarium. The only species thus far known near the type locality of M. marginata is M. alba (Aubl.) Wernh., which, however, has been collected much farther to the south in Venezuela. Two features noted in M. marginata: (1) lack of tertiary reticulation of the leaf blades and (2) corolla lobes one-third as long as the tube (Standley) or “corolla . . . ad 1/4 divisa” (Schumann), would exclude it from M. alba, in which the tertiary venation is well developed and the corolla lobes are, as in M. barbata var microcarpa (Schum.) Steyerm., longer than the corolla tube. I have not been able to confirm the matter of the relative length of the corolla lobes, although they would appear, from a study of the type photo, to be shorter than the tube. Wernham (p 43) places M. marginata under his “Species Dubiae v. Plus Minus Ignotae.”