Pollen morphology of the family Cistaceae in Egypt and its systematic significance

The pollen morphology of 11 species (including two subspecies and two varieties) belonging to two genera (Helianthemum and Fumana) of the family Cistaceae in Egypt was studied using light and scanning electron microscopy. Pollen grains of the studied taxa were found to be radially symmetrical and tricolporate. Pollen size, shape, apertures, and exine ornamentation characteristics were valuable parameters among the studied taxa. The largest pollen size was recorded in H. salicifolium and the smallest one observed in H. kahiricum subsp. schweinfurthii. Pollen shape in the Egyptian taxa varied from (sub-) prolate to prolate spheroidal, but F. arabica is different in having sub-oblate grains. The pollen data confirm that H. lippii and H. sessiliflorum are very closely related species. Pollen sculpture was useful in distinguishing between H. vesicarium var. vesicarium and H. vesicarium var. ciliatum. Three main pollen types of exine ornamentation were recognized: retipilate; reticulate to verrucate; and striate. Based on palynological data, a key for the studied taxa is suggested.