Question

Are prop roots adventitious?

Answer 1

Prop roots, also known as pillar roots, are a type of root that grow downward from the tree's branches. To support the dense and heavy branches, these roots have been modified.

Complete answer:
Roots that develop from areas other than the plant's radicle are known as adventitious roots. The injured root, nodes of the stem, internodes, branches, or any other tissue may produce these roots. An 'adventitious root system' is a collection of adventitious roots and their branches. These are often modified to provide mechanical assistance, support, food storage, and other critical functions.

Prop roots, also known as pillar roots, are a type of adventitious root that grows downward from the tree's branches. Their main purpose is to support the dense and heavy branches. The aerial roots are hygroscopic, which means they absorb water from the surrounding air (in the form of moisture).
These roots turn red as a result of this moisture absorption. The tips of prop roots have root caps. Prop roots become dense and pillar-like when they reach the surface due to the development of branches for proper anchorage.

It is very difficult to say the difference between the trunk and the prop roots, at this point. Interestingly, even if the trunk dies, the tree as a whole remains alive as the prop roots of the tree are supporting and nourishing the crown. Some examples are the Banyan Tree (Ficus benghalensis) and Mangrove plant (Rhizophora).

So, yes, prop roots are adventitious.

Note: Taproot and adventitious (also called fibrous) are the two main types of root systems. Adventitious roots have many modified versions, each for a specific purpose which can be classified as to store foods, to provide mechanical support and additional functions.