Underground stem, Aerial stem, and subaerial stem.
Explanation:
Plant stems can be Underground stem, Aerial stem, and subaerial stem due to its presence and strength of the stem. Underground stem are thick stems that run below the ground surface. e.g rhizome. Aerial stems are thin stems that can not stand erect. Examples include watermelon and strawberry etc. Subaerial stems are very thin stems that do not rise up but grow just above the ground. for example, water plantain, flowering rush etc.
The population size of a predator species is directly controlled by the population size of it's prey. If the predator has no prey the population size will go down because they have no food.
