Epidermal morphology of Permian Gondwana gymnosperms

Abstract

A review of cuticular features of species of the glossopterids reveals that most of the species from Karharbari and Barakar formations are hypostomatic while a few species in the Raniganj Formation are amphistomatic. Lateral walls of cells in species from older horizons are mostly straight, whereas, in Raniganj species they are often sinuous. Similarly, surface walls of cells of species of Karharbari Formation are mostly unspecialised, while those of Barakar and Raniganj formations may be papillate or non-papillate, striated or mottled and sometimes with epidermal hairs. In most species the stomata are anomocytic, irregularly oriented and distributed. Rarely, a regular distribution and a definite orientation is seen. In the older horizons the stomata may be dicyclic or partly amphicyclic besides monocyclic, whereas in Raniganj species they are usually monocyclic. Guard cells are mostly sunken in Karharbari species, normal and usually hyaline in Barakar species and sunken and thickened in the species of Raniganj Formation. Subsidiary cells are usually unspecialised in the species of older horizons, whereas in the Raniganj Formation they are usually papillate, invariably overhanging guard cells. No significant trend is observed in other gymnosperms.