Is it a grass or a tree?
Bamboo belongs to the class of Monocotyledons (Flowering plants whose seeds have one cotyledon.). According to the classic definition, no Monocotyledon is a tree, because only Dicotyledons (Flowering plants whose seeds have two cotyledons.) produce real wood.
A bamboo stem can't get bigger around over time, because it doesn't have any cambium, which is what causes trees to add girth. It is made of the same material, though (lignin (Organic substance, the second component of wood in trees.)), which makes it rigid enough to grow to 10 metres tall. This stem is called a culm – the name for all grass (Any member of the grass family.
) stems. Thatched roofs are made from culms: the stems of wheat, reeds or rye, all common grasses.
Bamboo stems grow so quickly that some people say that with a little patience you can actually see them getting taller. Bamboo has even been used to torture people: the poor victim would be tied to a bamboo stem, which would very, very slowly pierce his body.
