Epidermal Structure and Stomatal Ontogeny in Some Polygonales and Centrospermae

The epidermal structure and ontogeny of stomata in 19 speciesof Centrospermae and two of Polygonales are described. The cellsof the epidermis are polygonal, isodiametric, or elongated invarious directions and arranged irregularly. The anticlinalepidermal walls are thick, sinuous, straight, or arched. Eleventypes of glandular and eglandular trichomes have been observed.Six types of stomata: anomocytic, paracytic, stomata with asingle subsidiary cell, diacytic, anisocytic, and transitionalbetween diacytic and paracytic, have been noticed in the speciesinvestigated. The ontogeny of anomocytic stomata is haplocheilicor perigenous, while that of the other five types is syndetocheilicor mesogenous. Abnormal stomata with a single guard cell, unequalguard cells, aborted guard cells, and arrested development arecommon. Groups of stomata are also frequent but contiguous stomataare rather rare.