The morphology and taxonomic significance of pollen in the West African polygonaceae

Abstract

The pollen of Polygonaceae in West Africa was studied by light microscopy. Three pollen types are recognized. Type A is typical of Polygonum represented by P. plebeium. These pollen grains are small, 17.5 x 12.5 µm to 22.5 x 15 µm, quadrangular and prolate with thin exine walls (1.5 - 2.5 µm). The Pollen type B is restricted to the Persicaria group. The pollen is of medium size, 34.3 - 45.5 µm polypantoporate, spheroidal with germ pores on the entire surface. Type C pollen is possessed by other genera studied. The grains range from small to large, 19.2 x 19.9 µm in Symmeria paniculata to 51.6 x 44 µm in Antigonon leptopus. They are subprolate, prolate-spheroidal to oblate-spheroidal, triangulate in polar view and oblong, elliptic to round in equatorial view. Palynological evidence supports the segregation of Persicaria from Polygonum as well as revealed that Harpagocarpus is better placed in the tribe Coccolobeae than in the tribe Persicareae.