Ontogenesis and structure of phelloid in Viburnum opulus L.

Abstract

The ontogenesis and structure of phelloid cells was studied in the cork tissue of Viburnum opulus L. Phelloid was found to form as the result of division of various cells of the phellogen zone (from phellogen proper to subepidermal cells). There are quantitative differences in the phelloid which forms characteristic thickenings in its inner tangential walls in one- and may-year-old stems. These thickenings contain pectin compounds, cellulose and lignin but no suberin. Preliminary observations in the electron microscope did not allow identification of phelloid cells earlier than in the period when thickening of their walls begins. The strong contrast staining of protoplasts in these cells is noteworthy.