Ovule Ontogeny and Seed Coat Development in Gentiana, With a Discussion on the Evolutionary Origin of the Single Integument

In Gentiana both dermal and subdermal cells are involved in integument formation. The sequence and positions of the dermal and subdermal initials are reminiscent of the situation in bitegmic ovules and render it plausible that this single integument is derived from a dermal inner and a subdermal outer integument by the process of integumentary shifting. This study shows that the diversity in integument initiation in the sympetalous taxa is greater than is generally assumed.