CELL TYPES

• Parechyma cells have thin primary cell walls, are generally alive at maturity, and have a variety of functions.
• Collenchyma cells have unevenly thickened primary walls, are typically alive at maturity, provide support, and have plastic characteristics.
• Sclerenchyma cells have primary and secondary walls, may be dead at maturity, provide support (elastic), and some are involved in water transport.

Vascular bundle of monocot stem

Astrosclereid in leaf xs.

Fibers in oak wood xs, the fiber lumen shows as a dark portion in the center of individual cells.  Also note the paranchyma cells making up the portion of the vascular ray.

Angular collenchyma cells in celery petiole.