Seed development in Chondrilla juncea L

Abstract

A study of material from unstressed plants of Chondrilla juncea L. revealed a genetically based sterility in 3-4% of the achenes.

Embryogeny is of the Asterad type but the basal cell cb divides horizontally before the vertical division in ca. Polyembryony occurred but seems rare; probably only one embryo in each ovule reaches maturity. The endosperm was nuclear at first, becoming cellular after a number of free mitoses. The outer layers persist in the seed. The uniseriate endothelium develops a persistent cuticle on its inner face, which becomes closely appressed to the remaining endosperm layer as the endothelium degenerates.

Endosperm formation was erratic and independent of embryogeny. Because of the presence of aborted embryos associated with a well-developed endosperm, it is suggested that the degeneration is the result either of later formation of the endosperm or of unusually early cutinization of the endothelium.