Nature of Vestured Pits in Angiosperms

Abstract

VESTURED (cribriform) pits occur in many families of the dicotyledons and in many instances serve as taxonomic criteria between families. The nature of the vestures was first recognized by I. W. Bailey1 as “minute outgrowths from the free surfaces of the secondary wall”. General confirmation of this view has been obtained in a recent electronmicroscopic study of the vestured pits of Eugenia sp. In Fig. 1 the general form of the vestures and their attachment to the cell wall are apparent. In the unshadowed section in Fig. 2 it can be seen that the vestures represent outgrowths of the secondary cell wall and in some instances appear to arise from the pit membrane as well. It may be noted from Figs. 1 and 2 that the texture of the vestures is heterogeneous in that the outgrowth of the cell wall appears to be covered by a membrane which is extremely dense to electrons. This membrane is continuous over the vestures and forms a lining around the inner surface of the cell wall adjacent to the lumen (Fig. 1).