Observations on crossed lamellar structures in the cell walls of higher plants

Abstract

Crossed lamellar structures in cell walls have been known to occur with certainty only in some green algae. A number of higher plants in which it was considered this structure might be present have been examined, and it has been demonstrated in the phloem fibres of Vinca major and the tracheidal elements of the aerial root of Alstonia spathulata. In the latter two types of crossed structure are recognized, in one bands of laterally associated microfibrils c. 0.5µ wide intersect at variable angles, whereas in the other lateral association is complete, forming a crossed lamellar structure which approaches most nearly that occurring in the algae. In the outer layer of the secondary wall of wood fibres of Eucalyptus elaeophora and E. regnans there is inconclusive evidence of a crossed structure similar to that observed in the cell walls of some vessels, which consists of a loosely formed meshwork of aggregates of microfibrils. This structure is considered to be distinct from the crossed lamellar and cross-banded structures.