How do leaves of plants help in excretion?

Leaves of plants help in excretion in many ways:

1. Excess of water in plant is discarded by the process of transpiration that takes place through the leaves.

2. Gaseous waste i.e., carbon dioxide is removed through stomata present on the leaves.

3. Some waste materials get accumulated in older leaves. When old leaves fall, the waste materials are excreted along with the leaves.