 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. |