From what I remember it's called a substrate
Excretion<span> is the process of elimination of waste materials from the body. </span>Excretion<span>in </span>plants<span> is much simpler than that of animals and as such it </span>does not pose<span> any serious </span>problem in plants<span>. ... </span>Plants<span> use much of the waste products of catabolism in their anabolic process.</span>
I think the answer is a tendril.