Mechanisms Controlling Dormancy in the Arid Zone Grass Aristida contorta. II. Anatomy of the Hull

Abstract

The anatomy of the hull directly over the embryo was examined by light and electron microscopy in long-term dormant and non-dormant grains of A. contorta. A lipid-containing layer was noted, covering the surface of the inner epidermis of the hull, and examination by scanning electron microscopy showed that although the layer was intact in all dormant grain examined, it was fractured in non-dormant grain. A definitive statement on the function of these cracks is not possible, but they appear to be an anatomical change leading to increased gas permeability of the hull of non-dormant grains.