It looks like prop roots have sprouted on the stem that are used to attach to trees and structures.* They are sometimes called suckers or root-like structures. See the lower left picture here with the yellow arrows.* That's why it's best not to plant this in the garden.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.