treetop 树梢;
branch 树枝;
twig 小树枝;
bough 大树枝;
leaf 树叶;
sapling 树苗;
tree root 树根;
bark 树皮;
pith 木髓;
annual ring 年轮;
stump 树桩;
trunk 树干;
taproot 主根;
sprout 新芽
