The traditional character 樹 has 木 (wood) on the left — a tree is made of wood. The simplified 树 keeps the 木 radical.
culture
十年树木，百年树人 (shí nián shù mù, bǎi nián shù rén) — 'It takes ten years to grow a tree, a hundred years to nurture a person.' A famous saying about the value of education.
