stem tuber

例句：

1. 1. The stem of the tree is green and smooth.
   这棵树的茎是绿色的。
2. 2. The stem of the plant grows from the base of the flower.
   植物的茎从花的底部生长出来。
3. 3. The stem of the tree is strong enough to support the weight of the fruit.
   这棵树的茎足够强壮，可以支撑果实的重量。