Systematic study in Cressa cretica L. (Convolvulaceae) species from Lake Qarun, El-Fayoum province, Egypt

Cressa cretica L. is a monotypic species belongs to the plant family Convolvulaceae, tribe Cresseae. It is an erect, small, dwarf shrub, commonly grown in coastal areas and considered as an important medicinal plant with many therapeutic effects. Individuals of this species became restricted in specific areas in Egypt in became under threat of extinction. This study dealt with careful examination of the external and leaf internal structure beside pollen grain morphology. The study aims to understand the species morphological characteristics and protect it from localization and destruction processes. The results showed that the leaf macro- and micro-morphological characters are of the halophytic ones, with long unicellular hairs as well as T-shaped hairs and sunken stomata. The leaf internal structure has mesophyll differentiated into one layer palisade and spongy layers full of ca-oxalate crystals and salt glands distributed in the mesophyll. Pollen grains productivity was few and they are small, spheroidal to subprolate with tricolporate aperture and tectate perforate with supra-tectum granules. The results obtained show that Cressa cretica has external and internal halophytic structure in addition to few small pollen grains. Germination experiments needed to test the pollen productivity of this plant under non-saline habitats for its conservation.