Mushrooms, moss, and algae

*Omphalina* mushrooms sprouting from peat moss growing on a wet vertical rock face.

This delicate, tiny mushroom growing from Sphagnum moss is a species of Omphalina, possibly in the Omphalina pyxidata complex. Omphalina is a Basidiomycota, one of five divisions in the Kingdom Fungi. Basidiomycota is the fungus division that includes the white button mushroom, shiitake, boletes, and bracket fungi, among many others.

The Sphagnum moss from which the mushroom is sprouting was growing in an unusual place. It was in a shaded spot in a forest on a north-facing vertical rock face with water seeping from cracks.

On some of the moss plants there is bumpy green growth that may be an algae (Coccomyxa?). Is this Omphalina mushroom part of a basidiolichen and not a mere saprophyte?

Basidiolichens are a lichen symbiosis composed of a green alga (sometimes with a cyanobacterium) and a Basidiomycota fungus. Most lichens are formed by fungi in the division Ascomycota.

*Omphalina* fruiting bodies sprouting from *Sphagnum* moss. On the moss just below the largest mushroom are granules of a green alga.

The genus Omphalina has undergone taxonomic revisions lately and has been split into other genera. One of these is Lichenomphalina, a basidiolichen. Maybe the mushrooms in the photos are a Lichenomphalina, but until I go back to the site where I found it, I won’t know for certain.

Sarea difformis: A fungus that lives on conifer resin

**Black spruce resin with *Sarea difformis*.**

Conifer resin oozing from a tree is an inhospitable place. The terpenoid chemicals in resin are toxic to many forms of life, but not all. Even though conifer resins are full of anti-fungal and anti-bacterial compounds, some organisms have found a way around that. One of these is a fungus called Sarea, a genus of fungi that grows on the resins of pines, spruces, firs, and cedars. Organisms that live on resins are called resinicolous (resin plus “colous” meaning “inhabitant”).

From lichen to fungus

At one time, Sarea was thought to be a lichen, but because it lacks a photobiont (symbiotic photosynthetic organism), it has been “demoted” to a fungus. The tiny (barely 1 mm across) fungus bodies pictured above and below growing on the resin of a black spruce are, to the best of my knowledge, the apothecia (reproductive structures) of Sarea difformis. Cross-sections of the fruiting body examined under a microscope would make identification more certain, but that’s a bit out of my reach right now.

**A few small fruiting disks (marked by red arrows) of the fungus *Sarea difformis* are growing on the darker portions (are those part of the fungal body?) of the resin. Can you find more?**

I have looked for research papers on how Sarea can live on conifer resin, but the results have not yielded much information. Does it actually break down the resin components into simple carbohydrates? If so, then does it do this on its own, or is there a symbiotic relationship with bacteria or another fungus? Are the fungal hyphae growing in the resin or merely on top? How does it disperse? A lot of questions, and I’m sure there are answers somewhere.

Taxonomy

Sarea is a genus in the phylum Ascomycota (cup fungi, sac fungi), which includes familiar mushrooms like morels and the blue mold in Roquefort cheese. The taxonomy of the genus Sarea is not entirely settled, so some species may be moved to other genera, and species from other genera may be moved to Sarea. Also, new species are being discovered.

A similar resinicolous species that might be encountered in northern coniferous forests is Sarea (Zythia) resinae. It can be distinguished morphologically by the color of its apothecia. Sarea difformis has black apothecia, and Sarea resinae has orange apothecia.

Rare?

Sarea is not a rare fungus, but because of its small size and peculiar habitat, it is just rarely seen. It occurs throughout the cooler regions of the northern hemisphere.

Sources and additional reading

Pins and needles

**This may be a *Calicium* species. It has an immersed thallus. It is growing on weathered white cedar wood at the edge of a forest, and shaded most of the day.**

The black stubble in the top photo are the fruiting bodies of a lichen. I found them growing on a piece of weathered cedar of an old birdhouse. I had set up that birdhouse about twenty-five years ago at the edge of a field and forest. Over the years, as the forest grew around the birdhouse, these tiny lichens began growing on the wood.

Lichens are a varied lot. Depending on the species, they can look like dust, little shrubs, gossamer, leaves, or overlapping shingles. Some lichens, like the one in the top photo, resemble whisker stubble or tiny straight pins. They are, fittingly, called whisker lichens and pin lichens.

Whisker lichens are minute, measuring just 1 to 2 millimeters in size. Most only grow on old wood or the bark of old trees. Many species are considered indicators of stable forest environments with long-term ecological continuity.

**Whisker lichen apothecia. This species has an immersed thallus. Growing on a weathered balsam fir stump near the edge of a small wetland in a forest.**

Taxonomy

The fungal partner (mycobiont) in whisker lichens are members of the Ascomycota, a group of fungi known as cup fungi or sac fungi. Familiar Ascomycota include morels, penicillium molds, and yeasts that are used to ferment bread and beer.

The algal partner (photobiont) is a green alga, usually a species of Trebouxia, a genus of unicellular algae that exists in almost all habitats. They can be free-living, but many species form symbiotic relationships with fungi to form lichens.

Description and terminology

The thallus (body) of whisker lichens may be minutely rough-surfaced (verruculose-granular) or immersed. If immersed, the fungal hyphae and the algae photobiont grow just below the surface of the substrate.

Whatever the thallus form, the apothecia (fruiting bodies) are borne on a long or short stalk, or rarely, sessile. They may be gray, blackish-brown, or greenish-black. At the top of the apothecia is a globose to lenticular capitulum (“little head”), a cup-shaped structure that produces spores.

**A species of whisker lichen on an old white pine stump. Possibly a *Calicium* species.**

Determining species

Species determination in whisker lichens is complicated. Morphological characters can only go so far. At best, you might get to genus. For positive identification, microscopic examination of the capitulum and spores is necessary.

Finding whisker lichens

**Tiny whisker lichens are growing on or from this green crustose lichen on an alder branch.**

I have found whisker lichens growing on weathered jack pine twigs while photographing other lichens. Most of the ones I have seen seem to prefer old, weathered wood, but I did find one on green crustose lichen that was growing on an alder branch. It may have been a lichen parasite. These are interesting fungi that you can find with a hand lens, or in my case, a macro lens, scanning up and down the trunks and branches of trees, weathered wood, and other lichens.

An Afternoon in the Woods

Hardwood swamp still frozen but not for long.

On Saturday I took a canoe trip down the little stream with the big name (West Fork of the Moose Horn River) that passes through my property to visit the western section. This area is approximately 56 acres and forested. Most of it is upland aspen and spruce forest but there is a large hardwood swamp near the southern property line.

Another part of the swamp (finally) thawing out. Soon this will be a flowing stream.

The ground was still snow covered but it was melting fast in the warm sun. I spent most of my time in a portion of a hardwood swamp looking at tree trunks for lichens and fungi. I found several lichen species previously documented from here and possibly one new species for the list. There are also a number of unknown lichen specimens to figure out.

Shadow Lichen (Phaeophyscia orbicularis?) on a sapling black ash tree.

Shadow Lichen (Phaeophyscia sp.) with an unknown gray foliose species on a small but old red maple.

Shadow Lichen (Phaeophyscia sp.) on a sapling black ash tree.

Lung Lichen (Lobaria pulmonaria) on a small but old red maple

Appalachian Punctelia (Punctelia appalachensis) on a black ash tree.

Powdered Fringe Lichen (Heterodermia speciosa) on a black ash tree.

Frost Lichen (Physconia sp.) on a black ash tree

Saucer Lichen (Ochrolechia trochophora) on a black ash tree.

Four lichens: Script Lichen (Graphis scripta in upper right) and three unknowns.

There were two fungi that interested me. One is Phellinus igniarius, a polypore bracket fungus, that was growing on the trunk of an old quaking aspen. This fungus decays the lignin in the wood leaving behind the lighter colored cellulose and is one of the causes of white-rot in hardwood trees. The other fungus looks like P. igniarius and like it causes decay in living hardwoods. This one seems to only grow on black ash trees. It is a polypore but the pore surface looks shaggy rather than smooth. So far no luck in figuring it out.

Phellinus igniarius on quaking aspen.

Unknown bracket fungus on black ash.

Most of the trees in the hardwood swamp are black ash (Fraxinus nigra) with some green ash (F. pensylvanica), yellow birch (Betula allegheniensis), paper birch (B. papyrifera), American elm (Ulmus americana), quaking aspen (Populus tremuloides), and red maple (Acer rubrum). A year ago I measured the trees in the lower two-thirds of the swamp to get a population count by species and to calculate basal area. Some of the black ash trees are huge (for this part of Minnesota anyway). Of the 64 black ash measured 14 were between 28 cm and 44 cm in diameter. There were also 12 yellow birch in this size range. Black ash and yellow birch are slow growing trees even on good sites like this one so it is possible that the largest trees are at the century mark.