Structure and Ontogeny of Stomata in Some Polemoniales

Abstract

The ontogeny and structure of stomata in 22 genera and 51 species of the Polemoniales are described. Five main types of stomata noticed are: anisocytic, anomocytic, diacytic, paracytic, and stomata with a single subsidiary cell. Three modes of stomatal development: syndetocheilic or mesogenous, haplocheilic or perigenous, and meso-perigenous or syndeto-haplocheilic are observed. Abnormalities seen are: stomata with single guard cells, arrested development and contiguous stomata variously oriented. Contiguous stomata result from adjacently placed meristemoids or readjustment during maturation. Stomata with a single guard cell are formed as a result of degeneration of one of the guard cells before or after pore formation. The stomatal apparatus varies in different organs of a plant in form, number, orientation and arrangement of the subsidiary and also the surrounding cells. Three lines leading to Polemoniales, Boraginales, and Solanales are distinet.