Looking at plant tissues
Before any tissue is named it is worth seeing some. Three mounts, a microscope, and about half an hour.
You need
- A piece of the lower epidermis peeled from a betel leaf.
- A very thin slice of potato.
- A thin cross-section of the stem of a soft-stemmed plant such as kudalu.
Method
- Prepare a temporary mount of each of the plant parts above.
- Observe each one under a microscope.
- With your teacher’s help, try to identify the tissues — the groups of cells that belong together.
What each mount is good for
The betel epidermis
A single sheet of cells, so nothing overlaps. The easiest place to see that a tissue really is a group of like cells packed together.
The potato slice
Large rounded cells, all of one kind, filling the whole field. This is a food store, and the tissue that does the storing is the one met a few pages from here.
The stem cross-section
Several different tissues at once, arranged in a pattern that repeats around the stem. The hardest to read, and the most informative.
What to look for
Cell shape, how thick the walls are, whether there are gaps between the cells, and whether the cells in one patch all look alike. Those four questions are what the rest of this chapter answers.
One section is not one tissue
A stem cross-section shows several tissues side by side, not one. That is exactly why the tissues have to be classified before the section can be read — and it is why the next two pages go to a root tip, where the difference is far easier to see.