ABSTRACT
Scrophularia arguta is an annual caulescent plant. Native to North Africa, it can be found in Morocco and southern Algeria, in remote areas of the Atlas and the Sahara. S. arguta is a good example of the notion of an endogenous ability to flower put forward by Chouard, and the complementary notion of inhibition of this latent potential, since it is infrequent that flowering occurs without prior vegetative development. The LD requirement for the flowering of the main axis is the result of a regulatory hormonal balance in which cytokinins play a major role. Precocious flowering of basal shoots and their positive geotropism allow this species to fruit and drop in the soil seeds that do not show dormancy or inhibition by seed coats. The microphyllar shoots, prostate at first, then positively geotropic, have numerous flowers with a corolla that hardly opens: they are cleistogamous.
