Aerial roots - What are they? What are they for?

by Luis F. Blogger

I think we all have a pretty clear idea of what roots are. That is, they are the lower part of the plants that is underground and that has very important functions for their life, such as obtaining water and nutrients.

In any case, correctly and completely defining and classifying roots according to botany is a task that cannot be summed up in a single paragraph. We can name more than a dozen different types of roots.

In this article we will dedicate ourselves to analyzing one of those types, specifically the aerial roots. Although they are not so common, it is very easy to see them in indoor plants such as Monstera, orchids or pothos.

1. What are aerial roots?

In short, we can say that these roots are typical of parasitic plants, they grow downwards and can end up strangling the host plant. Because they are exposed to air, they are more likely to dry out, and are typically found on plants that live in humid environments, such as rain forests.

Being more specific, aerial roots are those that do not arise from the radicle of the embryo (that is, from the fertilized ovule) but from any other part of the plant. These parts can be underground stems, portions of the plant that sprout from the stem or stem base, or old roots.

In your indoor plants you will usually find them coming out of the pot, hanging from the plant. The most common is that you are tempted to cut these roots, since they look somewhat ugly, ruining the beauty of plants such as orchids. But with what we will see in this post you may change your mind.

2. What is the use of aerial roots?

Among the most important functions performed by aerial roots in plants such as pothos, we can mention the following three:

- They provide oxygen.

- They allow plants to spread, colonizing new territories.

- They improve the anchorage of the plant.

Let's look at each of these points in detail.

2.1 They provide oxygen

This type of roots occurs very commonly in plants in tropical areas where there are long periods of flooding. That is why in the times in which the plant is totally saturated with water, the aerial roots allow it to absorb oxygen.

Keep in mind that in those situations the conventional roots that are underground can take up very little oxygen since they are covered with water.

2.2 They allow to expand the plants

As you may know, there are many ways in which plants seek to reproduce and thus extend their domain. Undoubtedly the most common is the one carried out through the seeds, which with the help of other factors such as wind, water or some animals, can invade other areas. Aerial roots are another method that some plants have to extend their dominance.

If you have a plant with aerial roots at home and you place it in the ground you will see how the roots begin to spread, and if they come into contact with the ground it will generate a new plant. It is similar to reproduction by cuttings, since the new plant is a clone of the mother.

2.3 They improve the anchorage of the plant

Among the functions of the roots is to allow the plant to have an anchor to the ground. In parasitic plants, their aerial roots adhere strongly to the surface, thus improving anchorage. This means that in areas with high winds or in flooded areas, the aerial roots give the plant the anchorage that conventional roots cannot.

Surely you have seen a pothos that develops parasitically on another larger plant. Without the anchorage provided by aerial roots, this type of behavior would be quite difficult to see.

2.4 Additional functions

As we said, aerial roots are roots that are exposed to the air all or most of the time. This allows that, unlike the underground roots, the aerial ones in many cases have chlorophyll, being able to carry out photosynthesis. Subterraneans will never be able to photosynthesize as they do not receive sunlight.

On the other hand, we cannot fail to emphasize that these particular roots also fulfill all the functions that underground roots have. In other words, they can obtain water and dissolved minerals from the environment they are in, and store food for the plant.

With everything said so far I think you should think twice before cutting the aerial roots of any of your plants. ;)

Image source: Wikipedia