Studies of the surfaces of desert plant seeds: I. Effect of day length upon maturation of the seedcoat of ononis sicula guss

Pods of Ononis sicula may contain three types of seeds, all with embryos ready to germinate but differing in the time which they take to imbibe water: seeds which have matured during long days take longer than those matured in short days. The scanning electron microscope has provided evidence that the delay in imbibition by the 'long day' seeds is related to the thickness, i.e. the degree of development, of the cuticles of their seedcoats.