Three supporting tissues
A celery stalk bends a little. A walnut shell does not. Both are plant tissue. What differs?
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Celery's bendy support cells have thick corners. Shell cells have very thick walls. Lignin is the hard material in shell cell walls.
Rule
Rule: Parenchyma has thin walls and stores food. Collenchyma has thick corners and bends. Sclerenchyma has thick lignin walls and is hard.
- Parenchyma — living cells with thin walls and small gaps between them. They mostly store food. Green ones also make food. In pond plants, the gaps hold air and help the plants float.
- Collenchyma — living cells with thick corners. They give bendy support to young stems and leaf stalks.
- Sclerenchyma — cells with thick walls hardened by lignin. Many of them are dead. Find them in woody stems, nut shells and coconut husk fibres.
A simple tissue has one kind of cell. These three are simple. A complex tissue has several kinds of cell that work together. Xylem and phloem are complex.
Vascular means to do with tubes. Dermal means to do with skin.
| System | What it holds | Job |
|---|---|---|
| Vascular | Xylem and phloem | Carry water and food |
| Ground | Parenchyma, collenchyma and sclerenchyma | Fills the space between skin and tubes |
| Dermal | The epidermis | Covers the plant and slows water loss |