Cells and Tissues

Three basic cell types from a Helianthus stem cross section.

Simple pits between tracheids and adjacent parenchyma cells.

Lilium vascular bundle with xylem (red walls) and phloem sieve cells with associated companion cells.

Secondary wall structure in xylem tracheids.

Bordered pits in pine tracheids.

Helianthus stem cross section showing xylem and phloem tissues.

Xylem and phloem tissues in pine.

Quercus alba vessel element with simple perforation plates.

Quercus alba vascular tracheid - upper left inset shows nonperforate end wall, lower right inset shows pitting.

Quercus alba fiber tracheid.

Quercus alba libriform fiber with only a few pits and they are very small.