Kollenchym

Kollenchym, also known in English as collenchyma, is a simple plant tissue composed of elongated living cells with unevenly thickened primary walls. The wall thickening is typically concentrated at the corners of the cells, giving the tissue a flexible yet supportive structure. Collenchyma is distinguished from sclerenchyma, whose cells are dead at maturity and have lignified walls.

Kollenchym is usually located just beneath the epidermis in stems and petioles, and around vascular bundles in developing organs. The cells are elongated and remain alive at maturity, with walls that are thickened but not lignified. The walls are rich in cellulose and pectin, which allows plasticity and growth.

Development and function: Collenchyma arises during primary growth from the ground meristem. It provides mechanical support for growing shoots and leaves while permitting bending and elongation, contributing to the resilience of herbaceous plants. Because the cells stay alive, collenchyma can participate in wound responses and short-term nutrient storage.

Comparison: Parenchyma is also living and versatile but usually has thinner walls and a greater focus on storage and metabolism. Sclerenchyma has thick, lignified walls and is typically dead at maturity, providing rigid support. Collenchyma lies between these tissues in terms of rigidity and function.

Examples: In many herbaceous dicots, collenchyma forms in the cortex just inside the epidermis of young stems and in leaf petioles, such as in celery stalks and other flexible stems.

Kollenchym is the Dutch term for the tissue commonly called collenchyma in English.