The Value of Micromorphological Studies in Poaceae

Poaceae is the fourth largest flowering plant family in the world that is adapted to different types of habitats.There are ۱۲ subfamilies with ۵۰ tribes and ۸۱ subtribes in Poaceae. The efficiency of micromorphological data in systematic studies of the Poaceae is documented for the leaf blade epidermis, Glumes, lemmas, and paleas especially at the subfamily and tribal levels. Micromorphological features in lemma and palea as shape and distribution of silica bodies, long and short cells, different hair types as prickles, macro-hairs, and crown cells are of taxonomic importance. Intercoastal long cells are show different outlines and wall shapes. Straight wall and different undulation as curved, U-shaped, V-shaped, and especially Ω-shaped are found in Poaceae. In intercoastal zone, short cells are of diagnostic importance in form of their presence or absence and their shape. Silica bodies as an anti-feedant agent in the grasses caused enhanced strength and rigidity. By the presence of silica bodies, the water loss via cuticle is decreased. It is especially very functional in tolerance to the lodging, fluctuation in temperature, radiation, and drought stresses. Different shapes of silica are of taxonomicimportance. Epicuticular wax is a functional tool in confrontation with the environmental aridity by decreasing the water loss via epidermis surface and stomata. The presence of diketone-tubules, platelets, and longitudinally aggregated rodlets types in the grass family have been documented. The micromorphological variation in different groups of Poaceae taxa in Iran will be discussed to show the taxonomic value of several micromorphological characteristics of the leaf blade, lemma, and palea.

کلیدواژه ها:

leaf epidermis ، glume surface ، diagnostic features ، Iran