What is the difference between a plant root and a rhizome?
Roots, rhizomes, aerial stems, non-spreading rhizomes, communicating underground roots, what a mess! We take you to the discovery of the hidden parts of plants…..
Discovering these organs that are the roots of plants
What is a plant root?
The root of a plant is the part of the plant which will be used to anchor itself in the ground, and to feed itself.
They are generally underground, but can also be aerial.
What is the purpose of plant roots?
The roots of a plant will allow it to fix itself in its natural environment, to avoid being carried away by rain, wind, predators, and will allow it to interact with the soil in which it is located.
Some plants roots can even fight against soil erosion, like the Common screwpine and its stilt roots.
They also serve to feed the plant, by absorbing water and nutrients, and by acting as a storage organ.
Is a rhizome a root?
Even if the rhizome serves, like the root of the plants, as a storage organ, it is rather assimilated to a stem, which grows horizontally, in general under ground.
Unlike the roots, it has buds and nodes, which can give rise to both aerial stems and adventitious roots.
What are the functions of rhizomes?
As a reserve organ, it is used to feed the plant. But it can also be used, contrary to the roots, for the reproduction of the plant: indeed, knowing how to emit its own stems and roots, it can form a new plant once separated from the original plant. Growing horizontally, it is also used by the plant to propagate over long distances.
A few examples of rhizome plants
Among the plants with rhizomes, the best known underground rhizomes are probably those of bamboos, which can quickly become invasive, even if some like the Giant thorny bamboo have non-tracing rhizomes.
Some rhizomes can be aerial, like those of irises. When they thicken and have a swollen part, they are called tubers, like the potato or the dahlia.
Do the roots communicate?
It is always fascinating to observe the plant world, which is not only alive, but capable of many forms of communication and mutual aid. For example, it is regularly observed that trees come to the aid of their weakened or wounded fellows: they then pool their roots, and can thus share their resources in water and food. Conversely, this also allows a tree on the verge of death to pass on its last stored resources to its companions.
Trees can also alert each other in case of predator attack, either directly through their communicating roots, or through networks of fungi that act as intermediaries. The trees warned of the attack can thus develop a defense system, by emitting for example tannins which make their leaves bitter and inedible.
To learn more, please read Didier van Cauwelaert’s book, “L’émotion cachée des plantes”.
So, roots or rhizomes, a world not visible and yet so rich, fascinating to discover!
