Spiny hopsage fruit and seed morphology

Abstract

Rangeland seedings of spiny hopsage (Grayia spinosa [Hook.] Moq.) may be made with either bracted utricles or seeds. Problems have resulted from inconsistent use of terminology describing these 2 structures and the fact their germination and seedling emergence is not the same with similar environmental conditions and seeding techniques. We examined the flower, fruit, and seed morphology of spiny hopsage microscopically to resolve these discrepancies and provide a basis for discussing the functional roles of bracted utricle and seed components. The spiny hopsage fruit is a utricle consisting of a single disk-shaped seed contained within a thin pericarp. The utricle is enclosed in 2 papery bracteoles. Failure to recognize the obscure pericarp plus inaccurate use of terminology appear responsible for confusion in the literature. The presence and condition of seed and fruit structures can affect seeding requirements and embryo response to environmental conditions. Consequently, accurate identification of all structures associated with the fruit or seed combined with a review of seed biology and seedling establishment literature is essential for designing effective wildland seeding practices.