A solid base

Palms and bananas are also Monocotyledons. That means that they should never add any girth, because their stems don't contain any cambium either. No problem! Monocotyledons have come up with an ingenious solution to ensure that their trunks are capable of supporting their tree-like shapes.

Their leaves are massive, as are the leaf stalks, or petioles that hold them onto the stem. But when a leaf drops off, the base of the leaf stalk attached to the stem remains behind. On palms and bananas, these leaf sheaths (the base of the leaf stalks) build up layer upon layer, surrounding and adding girth to the stem. A pretty clever solution, don't you think?