Intrusive Growth of Secretory Oil Cells in Saururus cernuus

Idioblastic secretory oil cells are characteristic of many phylogenetically primitive angiosperms In Saururus cernuus (Saururaceae, Piperales) the oil cells occur throughout tissues of the shoot system and in certain floral organs They occur in surface layers as well as internally. The oil cells arising in the hypodermal layer grow intrusively into the epidermal layer, where they acquire a "new" surface wall facet exposed to the outside. The nature of intrusive growth, unusual in epidermis, is considered together with its effect on surrounding cells.