Trees and vines are often used as metaphors to describe kingdoms and countries (like in the eagle and vine allegory in Chapter 17): the rise and decline of these nations is just like the life cycle of plants, from growth to decay.
At one point, God compares Egypt to a tree that used to flourish and spread wealth and happiness around:
All the birds of the air made their nests in its boughs; under its branches all the animals of the field gave birth to their young; and in its shade all great nations lived. It was beautiful in its greatness, in the length of its branches; for its roots went down to abundant water. (31:6-7)