Lichens, Mosses, and Mushrooms

Besides the trees, shrubs, flowers, and grasses in the Park there are other living organisms. 
Lichens cover many of the rocks and trees. Though they look like splotches of paint, they are living communities made up of two types of organisms. The first is photosynthetic, and makes the food, and this organism is either a one-celled non-nucleated cyanobacteria, or a one-celled nucleated algae. Both of these have the ability to take carbon dioxide and water from the air and, using the energy from the sun, make sugar. The second part of the partnership is a fungus, a partner that provides a foothold on the rock or tree in return for a little bit of sugar. 
Several different types of lichen on the plinth near the western end of the planting bed in March.
One is pale, raised, and flaky. Another is small and green.
Close-up of the plinth seen above.
The lichen may be confused with spotted lantern fly egg cases, but the latter tend to be raised and more linear, without the flaky appearance.
Interesting gray lichen rings on the easternmost plinth in April
Brown lichen on one side of the easternmost plinth in April
White patch of lichen on the honey locust tree bark in the northeast triangle in March.
The rough bark of the three honey locusts seems to be a favorite substrate for lichen.
Mosses are true multicellular plants that lack seeds and the thin tubes that conduct water around taller plants. The sugar maple leaves at the top of the tree, 60 feet from the ground, get the water for their sugar recipe from the ground via the roots. The water is conducted to the top of the tree by super-thin tubes. These tubes are lacking in mosses, which explains why they are generally very short structures. What looks like moss on the trees in the Park is really lichen, but in early Spring the crannies in the vertical rocks capture enough moisture to support mosses. 
Lichen, not moss, growing on the south side of the honeylocust tree in the northeast triangle.
You can find thick soft masses of moss growing on tree bark in shady humid forests, but so far I have not seen any in Baldwin Park.
Thick, velvety moss growing on the upper surfaces of the stone plinth on the left.
The lichens will break up enough rock for a soil to form in a micro-environment, and the cool moist air supplies water. When the air gets dryer and hotter the mosses fade from sight until the next year.
Mushrooms are fungi (plural of fungus). They are not plants, and indeed are more closely related to humans than they are to plants. Like humans, the cells of a fungus have nuclei, and like us, they cannot make their own food. We have seen that fungi can form mutually beneficial partnerships in a lichen. We also saw here that the fungi adherent to the roots of trees and other plants can form mutually beneficial relationships. Another lifestyle for a fungus is that of a decomposer, eating dead things in the environment, things like a tree stump.
At least three species of mushrooms growing on the side of a tree stump in the southwest triangle in August of 2020.
The mushroom you see on the surface is the reproductive structure for a larger mass of fungal filaments that you don't see.
Botany 101 Bonus
There are literally tons of fungi in Baldwin Park. You just can't see them because they are underground and are in the form of very thin strands intertwined with the tiny root hairs of the tree. The term "mycorrhiza," from the Greek words for fungus and root, is the term used for these fungi in this relationship.
In 1988 E. I. Newman published a paper looking at the fungal filamentous connections not just on the roots of a single plant, but also between plants. In 1997 Suzanne Simard published a paper in the science journal Nature in which she explored this underground soil ecology. She showed that fungi and trees have a symbiotic relationship, in which the fungi help the roots absorb nutrients. That had been known. The fungi also allow communication between different trees, in return for a share of the food produced by the leaves of the trees. In Simard's words, the fungi and trees had "forged their duality into a oneness, thereby making a forest." The trees in a plant community, like the one in Baldwin Park, are not in strict competition with each other but share a socialist bent, nurturing and protecting each other at some expense to themselves, via the underground fungal connections.
Fine fungal filaments grow intermixed with the roots of a tree and also connect the trees underground, allowing transfer of carbon-containing nutrients and information: the wood wide web.
The ectomycorrhizal fungus intertwines with the fine roots of a tree and help those roots absorb nutrients and water in return for the food product of the tree.
Fungi also break down dead material and return nutrients to the soil, as seen on the left.
The mushrooms are the reproductive structures of the fungus and are usually the only part of the fungus seen above ground.

Matthias Baldwin Park 

423 N 19th St 

Philadelphia, PA 19130

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