Which of the following is NOT a feature of collenchyma cells?

Collenchyma cells are characterized by their living nature at maturity, which allows them to retain the ability to grow and elongate, contributing to the flexibility of plant tissues. One of their primary functions is to support young and growing parts of the plant while accommodating growth. They have unevenly thickened cell walls, which provide structural support without sacrificing the flexibility necessary for healthy plant growth.

The role of collenchyma in reinforcing growth is significant; they help reinforce new lateral and vertical growth, supporting the young plant structures effectively. Their ability to maintain vivacity while providing support is a key feature distinguishing them from other plant cell types, such as sclerenchyma, which is dead at maturity.

Thus, stating that collenchyma cells are non-living at maturity does not align with their biological function and characteristics, which is why this is the correct answer in distinguishing features of collenchyma cells.