I once heard, many years ago when I lived in Florida, that a palm tree is not really a tree;¬† it’s a grass!¬† I had never investigated the truth of that statement. ¬†But spending time recently in San Diego and admiring the many tall palms towering high over houses and even over other trees, made me want to find out whether it is, in fact, true that palm trees are actually grasses.
Even though palms seem like trees, with their height, their leaves, and what seems to be a trunk, it turns out that those traits are not enough to make them trees.
In fact, there are important differences between actual trees and palms. ¬†For example, unlike trees, palms have no bark or woody tissue.¬† Palm trees do not produce a cambium layer–that part of a tree between the bark and the interior, that produces new growth each year. ¬†A horizontal cut through a tree’s trunk would show growth rings; ¬†a cut across a palm’s would not. ¬†A palm’s ‘trunk’ is simply a mass of spongy, hardened material that expands as the palm grows taller.
And palm trees lack a key ability trees have–to resist death from disease or injury. ¬†A tree can ‘seal off’ a damaged portion, entirely separating it from the tree’s healthy part, so that the tree can continue to live and grow.
In addition, conventional trees experience a secondary growth phase, when functioning tissues are replaced with younger cells.¬† But palm trees do not undergo such a process of cell replacement.¬† Instead, a palm tree’s individual cells endure for the plant’s entire lifespan of 100-740 years.
Palm trees are indeed amazing.¬† But, as it turns out, they’re amazing grasses, not amazing trees.–April Moore