Studies on the Morphology of the Onagraceae. II. Embryonal Manifestations of Fasciation in Clarkia elegans

Abstract

Material was obtained from pedigree cultures. Megagametogenesis is normal. Fertilization, which proceeds unusually slowly in fasci-ated plants, is described in detail and is normal. The genesis of such teratological phenomena as fasciations, unilateral or monocotyledonous embryos, tricotyle-dony, etc., is to be found during all stages of embryo-genesis. These phenomena represent neither advancing nor retrogressive evolutionary steps, but in the end contribute to the changing evolutionary status of the species because they are heritable. The possible appearance of these anomalies can be ascertained in advance. Diploid apogamous embryos, which apparently originated from megasporocytes that failed to undergo meiosis, are described.