Pollen morphology of Curroria, Mondia, Socotranthus and Stomatostemma (Periplocaceae)

The pollen morphology of I Planch., O Skeels, Socotranthus Kuntze and Stomatostemma N.E. Br. was studied.All the genera are characterized by pollen grains arranged in tetrads. The arrangement of the grains may be rhomboidal, tetrahedral or decussate. The 4 - 6 pores present are restricted to the junction area of adjacent grains. The exine is smooth.Exine structure consists of an outer, homogeneous stratum (tectum) subtended by a granular stratum. The intine is well developed. The pollen grains of tetrads are connected by wall bridges (cross-wall cohesion). Except for small differences which may occur between species and genera in pollen size and arrangement of tetrads, the pollen is uniform in morphology.