Collenchyma

Abstract

Collenchyma is a plant tissue particularly adapted to withstand tensile stress. It has thickened, nonlignified cell walls that resemble the primary walls of growing plant cells in pectin and hemicellulose composition but have more axially oriented cellulose microfibrils. The strong orientation makes collenchyma a useful model system for structural characterisation by FTIR and scattering methods. Collenchyma strands in plant stems normally underlie the epidermis where, stretched by turgor in the parenchyma, they contribute maximally to the bending stiffness of the stem. In leaves, collenchyma strands are located along veins and around the edges where they resist tearing when the leaf flutters in the wind. Unlike wood, collenchyma is capable of elongation growth. How growth is reconciled with axially oriented cellulose and high tensile stiffness is a puzzle that has implications for plant growth in general. Key Concepts Collenchyma is adapted to withstand tensile stresses. Compressive stresses are carried by turgor pressure in cells adjacent to collenchyma. Collenchyma cell walls resemble typical primary cell walls in composition but have axially oriented cellulose microfibrils. Collenchyma is a useful model system for studying primary cell walls. How collenchyma accommodates growth has implication for the mechanism of plant growth in general.