Monographs Details: Stifftia
Authority: Carlquist, Sherwin. 1957. Anatomy of Guayana Mutisieae. Mem. New York Bot. Gard. 9 (3): 441-476.
Discussion:The genus Stifftia, although not found on the Guayana Highland, shows some
degree of relationship to the above genera and may be considered in this connection.
The pollen grains of Stifftia chrysantha (fig. 91 A, B) have a remarkable
feature not previously reported for Mutisieae. Evenly arranged on the surface of
these grains are eleven areas of thickened exine, three on each intercolpar face
and one at each pole. These thickenings are the result of greater development
of the outer ektexine (fig. 91 B). Numerous wide but very short spines or emergences
occur on the thickened areas of the exine as well as on the unthickened
areas. However, no such thickened areas are found on the pollen of Stifftia uniflora,
the grains being evenly spinulose. The pollen grains of S. uniflora, not
illustrated here, would match closely the drawings of Chimantaea rupicola in
figure 93 A, B. In shape, the pollen grains of these two species of Stifftia are
dissimilar, since S. chrysantha has large, subprolate grains, while those of S.
uniflora are smaller and prolate sphaeroidal. Excepting the thickened areas in S.
chrysantha, the exine thickness of these two species is very similar; likewise
both have long, narrow furrows.