Few trees create a stronger impression than the mighty oak. Here in the southern part of the United States, oak trees can create an even stronger impression when they have moss draped on their branches. But the appearance of these mosses can cause alarm to those worried about the well-being of their oaks. Knowing a little more about what kind of moss grows on oak trees will help homeowners develop a better grasp on this issue.
Technically speaking, moss is an epiphyte. An epiphyte is a family of plants that grows against another surface for support without taking nutrients from it. However, ball moss in particular isn’t considered a “true” moss but rather part of the bromeliad family, a family of flowering plants.
Ball moss is the kind of moss that grows on oak trees most often in Texas. These bristly, ball-like plants favor the shady places inside the tree canopies. A small amount of ball moss won’t do too much damage to your oak tree since it doesn’t steal its nutrients. In some cases, when ball moss grows on an interior branch, it may cause it to fall off from the weight. But these are usually interior branches that have already died due to lack of sunlight, a natural occurrence in oak trees. In some cases, ball moss may harm a tree that is already weak, but on a healthy tree, it should pose little threat.
Many people are surprised to find out that the light green, lacy-looking moss that hangs from the branches of trees throughout the southern United States is also technically not a moss. Spanish moss is another member of the bromeliad family. Like ball moss, it doesn’t steal nutrients from the tree itself and therefore won’t kill or damage a tree. However, a tree that’s dying may grow more Spanish moss because the thinning canopy allows more sunlight in.
Mossy-looking lichens do grow against sunny places on trees and other objects, but they’re also not mosses. In fact, they aren’t even plants. Lichens are fascinating studies in symbiosis. They’re what happens when two types of fungus and an alga grow into a single organism, which can then thrive in an area that none of them could individually.
Lichens do not have roots. They get their energy from the sun and don’t penetrate deeply into the object to which they’re attached. So, a lichen will not harm a tree. However, lichens—like Spanish moss—often appear in greater numbers on a tree that’s dying since the loss of leaves leads to a greater amount of sunlight on the bark. If you notice a greater number of lichens, contact one of our certified arborists in Austin, Texas, for a consultation.