The New York Scalewort
It is common to get questions about what kind of “fungus” is growing on the bark of a tree. When I got a call recently about a “fungus” growing on trees, I immediately started describing lichens to the caller because such calls often turn out to be a lichen. A lichen is an organism, or rather two organisms, made up of a fungus and an alga (to learn more about lichens, visit this link: Do Lichens Cause Harm to Trees?). The caller insisted that it was not a lichen they were seeing. In this case, the “fungus” turned out to be a liverwort, specifically the New York scalewort.
The New York scalewort (Frullania eboracensis) is a species of liverwort in the Frullaniaceae family. It is most commonly found growing on the trunks of hardwood trees and can be very visible on trees with a lighter gray colored bark. It grows in a branching pattern, and I have seen some that resemble a large, dark snowflake on the side of a tree. It has very small leaf structures that look more like scales than a leaf. This scalewort grows flat against the bark of trees, and its color can be brownish, reddish, or even olive green. It is common in eastern North America and southern Canada and prefers shady, moist areas.
The New York scalewort is often confused with a species of moss. As a species of liverwort, it does have something in common with mosses: they do not have a vascular system to conduct fluids and nutrients. This lack of a vascular system limits them to a small size. The leaf structure of the New York scalewort forms a helmet-shaped pocket that can store small amounts of water and help this species survive in relatively dry conditions.
This scalewort is dioecious, meaning it forms male and female reproductive organs on separate plants. The plants form gametes, and when they unite, a sporophyte grows out of the female organ. The sporophyte has a small, brown or black capsule on a white stalk. When they mature, spores are released into the wind to be carried to other locations. The New York scalewort can also reproduce asexually when a piece is broken off and moved to a new location.
The New York scalewort poses no threat to the trees on which it grows. In the same manner as lichen, the tree is just a place for it to reside. It does not penetrate the tree and does not take any nutrients from the tree. Instead, the New York scalewort absorbs the water and nutrients it needs from the rain, fog, and dew.
