You will listen to part of a lecture and answer a question about it. After you h

Now listen to part of a lecture in a biology class.
    Roots are not always underground. When they arise from the stem and either pass for some distance through the air before reaching the soil or remain hanging in the air, they are called aerial roots. Simply put, aerial roots are roots that grow on the aboveground parts of a plant. Aerial roots serve several functions for a plant. But today, we will first look at two examples to better understand this phenomenon.
    One function of aerial roots is support. A good example of this is the maize plant, also commonly known as corn. The maize root system is fibrous and shallow, meaning that the roots are weak and do not go deep into the ground. The underground root system cannot adequately support the tall plant. The maize plant compensates for this inadequacy by growing aerial roots from the lower stem segment to prop up the plant. These aerial roots go down in the soil and further branch out, giving the plant the additional support it requires. The supportive aerial roots protect the maize plant from high winds so that it doesn’t not get blown away.
    A second function of aerial roots is to absorb moisture and nutrients, just like underground roots. Plants that live in marshes and bogs have underground roots, but these roots can’t absorb gases from the air because they are constantly underwater or submerged during high tide. An example of this is mangrove trees, which use aerial roots for aeration and not water absorption. Mangrove trees are found in swamps and bogs, which are wet environments affected by tidal patterns. Mangrove trees produce aboveground roots to help them with air exchange, absorbing, converting, and storing nutrients crucial to the development and survival of the trees.