Secondary Xylem and Tyloses in Stems

In the scanning electron micrograph image at left, three secondary xylem vessels are positioned side-by-side. Lateral movement of water and minerals diffuse through pits on their side walls.

A ray composed of ray parenchyma cells is also shown.

Shoot Secondary Xylem Tissue XS SEM

Tyloses are common in Vitis. A tylose is formed by a parenchyma cell that has grown through the pit of a vessel member.

Below the tyloses in the vessel at right is a simple perforation plate. This plate indicates where two vessel members have joined together to form a continuous conducting tube.

The arrow depicts amyloplasts enclosed in a ray parenchyma cell. Amyloplasts are starch storing plastids.

Note the bordered scalariform pits on the walls of the vessel at left.

Shoot Secondary Xylem Tissue LS SEM

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Stems Secondary Growth