Roots

This page is part of the lab Plants II, which includes these lab pages:

This lab is a continuation of Plants I, with the goal of helping you understand plant evolution, structure, and function.

Reading: You'll need your textbook for this one. You should look over Chapter 35: Plant Structure, Growth and Development in Campbell Biology.

This lab involves a lot of microscope use; you should also take a look at the microscopes page.

The first thing to remember about roots is that they're different from stems. A root cross section will be round and will contain more or less the same tissue types as a stem, but the arrangement of those tissues is different.

Ranunculus (buttercup) root

Ranunculus root, cross section

This is a dicot with no secondary growth. The vascular tissue phloem and xylem) is in the center, surrounded by a layer of endodermis. The endodermis contains the casparian strip and helps control the movement of water and nutrients into the vascular tissue. The xylem consists of large, thick-walled cells that are stained red. The phloem consists of smaller, thin-walled cells that are stained blue. The phloem surrounds the xylem. Much of the root is filed with cortex, a ground tissue.The epidermis helps control the movement of water and nutrients into the root.

Smilax (greenbrier) root

Smilax root, cross section

Smilax is a monocot with that grows as a woody bush or vine. This root has the same tissues as the Ranunculus root, with a slightly different arrangement of the vascular tissue in the middle.

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