A Shortcut to Mushrooms: Basics

Unidentified orange mushrooms grow in the decaying leaves under aspen trees near Pike's Peak. These have defied attempts at identification, and I would welcome input if a reader has any ideas. The mycoflora of Colorado are so diverse that even after appreciating mushrooms for many years it is still possible to be stumped!

     I thought it would be good to actually address the third major category of low-growing interest that this blog is intended to address: mushrooms. Mushrooms are a beautiful and bizarre addition to the 'flora' of the Rocky Mountains, as indeed they are not plants. Mushroom-producing fungi thrive in virtually every environment in Rockies, but are either so small or evanescent that they are easily overlooked. They come in a dazzling profusion of shapes and sizes that have been very engaging to learn about over the past few years. I thought it advisable to do a post on mushroom basics before digging into any of the particulars, as the knowledge and terminology needed to appreciate mushrooms can be arcane, if not so byzantine as for lichens. 

Environment: Where the Mushrooms Grow  

     Any species of mushroom is happier in a moist environment, frequently with the presence of warmth. Would-be mushroom hunters know well that the best time to search for mushrooms in the Rocky Mountains of Colorado is between July and early September at higher altitudes where precipitation and residual moisture from snow melt create a damp, fertile mat. Fungus species which produce mushrooms may be saprophytic, deriving their nutrition from dead organic matter, or may be mycorrhizal, mutualistically growing with the surrounding trees. Which trees a given mushroom shows a preference for can be an important factor in locating and later identifying them. 

Ideal mushroom habitat: deep, wet forest on a north-facing, high-altitude slope in mid-July. 

Anywhere great moss mats like this flourish indicates that mushrooms may lurk nearby. 

     Moisture and warmth promote the health and happiness not of a mushroom per se, but of the actual body of the fungal organism. This is a network of fibrous mycelium which grows on and just under the surface of the soil. Mushrooms simply represent this organism's "fruit;" reproductive structures comprised of alarmingly fast-growing mycelium that rapidly rise from the detritus of the forest floor for to produce spores. This means that the bulk of fungal organisms in the mountains are always present even when they are not visible, quietly performing wood rotting critical to the development of forest soil(1). These fungi will fruit when the host mycelium are healthy, and moisture and temperatures levels are right. A good time to hunt for most mushrooms is after copious rains followed by a day or two of sweltering summer heat. 

Parts of a Mushroom: What You Are Seeing When You See a Mushroom

      "Mushroom" is not exactly a scientific term. I've chosen to define it as any non-lichen, non-mold fungal structure that macroscopically grows erect from its substrate. Most mushrooms are the fruit of fungi classified as Basidiomycota, a gigantic phylum of fungi which bear their spores on microscopic structures appropriately known as basidia. Basidia are microscopic, pedestal-like structures which hold spores aloft from their more distal ends. There is no unifying, macroscopic gestalt for basidiomycetes, but virtually all umbrella-shaped or shelf-shaped mushrooms with gills, pores, or tubes belong to this broad category. I have included an illustration below of common parts needed for identifying many basidia-bearing mushrooms which can be loosely sorted into gilled mushrooms and boletes. I have included general descriptions of some other varieties of fungi that could be considered mushrooms as well.

     The terminology of mushrooms is much more accessible than that of lichens, so I have only included an attenuated guide. Glossaries such as this one are easily found online and provide a wealth of accurate information on the language of mushroom morphology. The books in the references for this post(1,2) are great resources for further learning as well.
     Finally, in some of the photographs I have also commented on the edibility of the species shown, as mushroom hunting for the table is a popular pastime in Colorado and an interest of mine personally. 

Structures of Gilled Mushrooms, The order Agaricales 

     The order Agaricales consists of a vast majority of what most people would consider to be a "mushrooms." With one notable exception (see below), any mushroom with apparent gills belongs in this order, and all true gilled mushrooms are in Agaricales. Not all Agaricales have all the features listed below, and some have features which are not listed below.  

Features of a gilled mushroom as seen in Amanita muscaria. Not all gilled mushrooms have all the features seen here, 

but A. muscaria has most features that a gilled mushroom could potentially have. 

1. Cap (pileus): Structure perched on top of the stem, which shields the gills from rain and sun. Important field marks include: 
• Color. 
• Shape: convex, concave, shield-shaped, conical, or myriad others.
• Presence or absence of universal veil remnants (seen here as white bumps).
• The features of the margin of the cap (the edge of the cap closest to the gills). In this illustration A. muscaria has a striate margin, which refers to the tiny, uniform grooves which appear around the edge of the cap. 
• The feel of the cap, which may be slimy (viscid), color-changing in relation to water absorption (hygrophanous), dry, cracked, or any number of features.      
2. Gills: the fertile structure (hymenium) of a mushroom which produces spores. Important field marks of gills include: 
• How or whether the gills attach to the cap and stalk.
• Color, which is prone to change as the mushroom matures.
• The distance the gills are from each other and whether the gills are parallel or forked. 
• Spore prints are a critical feature of mushroom identification which are gained by laying the gills upon a contrasting medium of some sort. Oftentimes it can be difficult to distinguish mushroom species from each other without knowing the color of the spores. 
3. Stem (stipe): the supporting structure which holds up the cap. Important field marks include:
• The presence or absence of a well-defined stem at all. Not all gilled mushrooms have a well-developed stem, especially those with a more shelf-like habit such as oyster mushrooms.  
• The presence or absence of a partial veil remnant (see below)
• The structure of the stem: hollow vs. solid, snapping cleanly like chalk or folding, the presence or absence of universal veil remnants at the base (see below). 
• The shape of the stem: whether it bulges noticeably, its length in relation to the size of the cap, etc. 
4. Partial veil remnant (annulus, ring): a ragged, often ring-shaped remnant of a partial veil which hangs from the stem of the mushroom. What the veil looks like, as well as whether it is present at all can be important field marks. 
5. Basal universal veil remnants (volva): a sac-like structure which hugs the base of the mushroom. It is the remains of a sac that covers the entire mushroom as it develops, and the shape of the volva along with its presence or absence can be a useful field mark. 
6. Hyphae fibers: hair-like or root-like projections from the base of the mushroom that connect it to the mycelial body of the greater fungus. In many species these are too small to be visible, but some species have a pronounced "root" or hairy projections which can be useful for identification.  

Examples of Gilled Mushrooms

An unidentified mushroom in the genus Amanita, possibly A. populiphila found growing around 8,000 feet in Golden Gate Canyon state park. The well-defined volva is characteristic of this genus. Note the debris stuck to the cap, indicating that it was viscid at some point. The margin of the cap appears to be becoming striate; in my experience striate margins become more apparent with age. This species is edible, but any collector should use extreme caution when collecting Amanitas as many similar-looking mushrooms within the genus are deadly poisonous, sometimes even with prompt medical care(2). 

A different view of the same Amanita. This picture shows the partial veil as it separates from the stem. Most Amanitas maintain an annulus (ring) on the stem, although a poorly-understood species complex of exannulate (ringless) Amanita species thrives in Colorado(1). This species likely fits that description, as its partial veil is seen here cleanly separating from the stem.  Note how the gills are unattached to the stem, a hallmark of this genus.

Another Amanita, this time A. pantherina. The volva and annulus are clearly visible. Universal veil remnants can be seen clinging to the cap as scruffy white bumps. Although it is not visible in this photo, the gill attachment in this mushroom was separate from the stalk. The combination of volva, annulus, and separate gills is diagnostic of the genus Amanita(2). Relatively few mushrooms in the Rocky Mountain region are deadly poisonous, but among those that are the genus Amanita is disproportionately represented(1). A beginning mushroom hunter should learn to identify mushrooms in this genus before any others. A. pantherina is poisonous, although not deadly. 

Lactarius deliciousus growing in mixed pine woods near Empire, CO. The mixed orange and pistachio coloration is distinctive of this species, as is the close gill attachment. As with other Lactarius species, fresh breaks in the cap will exude an orange latex. You can see some hairy hyphae radiating from the bottom of the mushroom at left. Although this species is edible, contrary to its name it is apparently not delicious(2). 

An Agaricus species growing in someone's lawn in Littleton. Like many mushrooms, Agaricus ssp. are relatively easy to differentiate to the genus level and more difficult to tell apart at the species level. Agaricus is the home genus of the familiar pizza mushroom A. bisporus, which many mushrooms in this genus resemble. Note the chocolate-brown gills which are not closely attached to the stem, the annulus, and the fleshy gray color of the overall mushroom. The presence or absence of a volva can be useful in differentiating a potentially edible Agaricus from a deadly Amanita. 

Gilled LBM's (little brown mushrooms) co-inhabiting deadwood with a Cladonia lichen. Most gilled mushrooms fall into this frustrating designation, whose characters require a microscope, chemical analysis, or psychic powers to differentiate. With few exceptions, the LBM designation is good enough to know that it's time to move on.

Structures of Stemmed, Tube-Bearing Mushrooms: the Order Boletales 

     Most mushrooms which have a well-defined stipe, soft flesh, and spongy tubes which bear spores fall into the order Boletales, colloquially referred to as boletes. This is not foolproof, as there are mushrooms which are considered to be "gilled boletes," but generally this order is easy to identify. Polypores (see next section) also bear their spores in tubes, but are generally different enough from the boletes in other ways that the two are unlikely to be confused. Some common characteristics of boletes are noted below.

Typical Boletales features as seen in Boletus edulis. Bolete-like mushrooms tend to have fewer 

complex features than gilled mushrooms. 

1. Cap (pileus): as with Agaricales. Note the pine needles clinging to the cap in the illustration. Forest debris clinging to the cap, even if the cap is dry, is a good indicator that the cap was viscid at some point. Bolete caps tend to be soft and fleshy.
2. Pore tubes: the hymenium in Boletales tends to be a spongy surface composed of thousands of tiny tubes. A spore print may be obtained from these tubes as from a gilled mushroom. Some boletes have tightly packed tubes, while others have more loose, spongy appearance.
3. Stem (stipe): as with Agaricales, but I am unaware of any Boletales which maintain veil remnants of any sort. The characteristics of stems in Boletales such as whether it is scabrous, reticulated, or smooth are important field marks. The interior of the stem may have hollow cavities or spongy spots within it, either due to the structure of the mushroom itself or due to being eaten by maggots. Stems may also capture falling spores from the cap, allowing for a sort of field spore print that can be useful for identification.  

Examples of Boletes

Boletus edulis, a much prized and richly-flavored edible bolete growing under blue spruce at about 

10,000 ft. Note the needles adhering to the cap, indicating it was viscid at some point.

Another angle on B. edulis. You can barely see the spore tubes peaking out from between 

the cap's in-rolled margin and bulbous stalk. 

A tubed mushroom in the genus Suillis, likely S. granulatus. Suillis species are colloquially known as slippery jacks or slippery jills thanks to their slimy caps. Many occur in the Colorado Rockies, and I am not aware of any that are poisonous. Some of them are reported to be decent edibles when they have been de-slimed(2). 

The underside of  S. granulatus showing the wider, spongier tubes characteristic of the genus Suillis. The cinnamon coloration on the stalk is likely due to spores falling from the cap. This mushroom was growing in a mixed pine and aspen forest at about 10,000 ft near Pike's Peak. 

Polypores, Puffballs, and Asci, Oh My!

     Three categorizations of fungi that could be loosely termed mushrooms are also worth mentioning in orienting a mushroom lover. These are the polypores (order Polyporales), the puffballs (genus Calvatia), and the ascomycetes (phylum Ascomycota). Polypores and puffballs are both bear their spores on basidea, while ascomyscetes are classified due to their sac-like spore-bearing structures (see below). I have included these types of fungus based entirely on their shape, as their taxonomic groups range from quite specific to gigantic. 

Polypores 

     The polypores include a large array of fungi which tend to have a bracketed or shelf-like habit, tougher or "woody" caps, and which bear their spores in tubes. The tubes may look similar to those seen in Boletales, but the bracketed shape and tough, slow-rotting flesh of the polypores sets them apart in most instances(1). This order includes the ubiquitous and beautiful Trametes versicolor (turkey-tail), as well as most shelf-shaped conk fungi one encounters in the woods. Information on the edibility of these fungi is typically pointless, as most of them have the gustatory characteristics of an old boot. Below are some photos of a native polypore. 

Gleophyllum sepiarim, otherwise known as the gilled polypore, growing on some downed pine near Pike's Peak. The tough cap and shelf-like habit are classic indicators of a polypore. This fungus is an important contributor to mountain soils decomposing wood via brown rot.

The underside of G. sepiarim. The "gills" are actually just furrows in the fungus' tube-forming hymenium. Most polypores have a smoother underside than this one. 

Puffballs

 

     The puffballs are an easily-recognized group of basidiomycetes which bear their spores on an internally-grown hymenium. As the fungus matures and dries, the spore mass is ejected through a tear in the fungal body, creating a pleasing poofing effect. Often found fruiting on the ground in forests and meadows, they can often look like unusually symmetrical or smooth rocks until more closely inspected. Young puffballs which are white on the inside tend to be edible. Below are some images of familiar puffballs from the Rocky Mountain region. 

A staggeringly beautiful woman holds a fist-sized Bovista plumbea found in a meadow around 10,000 ft in elevation near Pike's Peak. A wet summer supported fruiting in a normally arid, rocky meadow. 

The same puffball as above cut in two, revealing the hymenium. The color of the interior of a puffball can be an important field mark, especially since ones with black or yellow spores tend to be poisonous(2). 

The gem-studded puffball, Lycoperdon perlatum growing in spruce and fir woods. This species grows practically everywhere in the Rocky Mountains and is easily characterized by the studs on its outer surfaces and white interior. L. perlatum seldom grows larger than a few centimeters.

Sac Fungi: Phylum Ascomycota 

     Some fruiting bodies of members of the phylum Ascomycota may be considered "mushrooms." The ascomycetes are highly varied group of fungi holding such seemingly disparate members as brewer's yeast, morels, and truffles(2). They are so named because they bear their spores in sac-like structures called asci, as opposed to the basidia of the gilled mushrooms and many other fungi. These structures are microscopic, but the fruiting bodies of both ascomycetes and basidomycetes tend to look different macroscopically as well. Mushrooms produced by ascomycetes do not follow a pre-determined set of morphological characters, but seem to manifest as many of the bizarre, non-umbrella shaped lumps and oddities that lurk in the corners of the forest floor. One recognizable set of mushrooms that are consistently ascomycetes are any cup-shaped fungi, including most of the species which symbiotically create lichens. The similarities between the reproductive structures of many lichens and cup-fungi are immediately apparent with casual observation. 

Scutellina umbrorum growing on sphagnum bog at around 10,000 feet. The cup shape seen here is not characteristic of all ascomycetes, but virtually all cup-shaped fungi such as these are ascomycetes. These fruiting bodies are quite small, no more than 1.5 cm across. 

A Xanthoparmelia lichen, possibly X. coloradoensis, growing on granite. Note how the apothecia of this and many other lichens closely resemble the cup-shaped habit of some mushroom-forming cup fungi. 

Morchella brunnea, the much sought-after gourmet black morel, is also an ascomycete. The morel is unusual for a mushroom in that it tends to fruit relatively early in the season. This specimen is being consumed from the top down by mold.

Not Sure if Mushroom or Alien

     A final group of organisms that might very, very loosely be termed mushrooms is the slime molds. Slime molds are a fascinating set of organisms which vacillate between being unicellular and colonial, and which behave (there's no better word for it) in such a way as to ingeniously adapt to their environments without the benefit of a nervous system. An exploration of slime molds is beyond the scope of this post, but they are fascinating organisms and I recommend reading up on them if you want to learn about something truly fantastic and alien. Slime molds are intuitively fungus-like at a glance, but are unlikely to confused with any species that would be thought of as a mushroom by a sober hiker. 

Stemonitis splendens, whimsically known as the chocolate tube slime mold for its habit of metamorphosing into a colonnade of chocolaty brown tubes later in its development.  I have only seen slime molds in the Rockies in the same warm, moist habitats that are favored by mushrooms.

     Thank you for reading about the varied world of mushrooms! This post was a beast, but I hope that it contains a lot of good information for the fruiting mushroom enthusiast. Do bear in mind that I tried to cover a lot of ground here, and that many distinguishing characteristics of mushrooms require a great deal of practice to differentiate. Likewise, many fungi adopt forms that simply do not fall neatly into any of the categories above being antler-shaped, gumdrop-like, sponge-like all over, and many others. The joy and the frustration of getting in the dirt with fungi is in teasing apart all these distinctions to figure out what you are dealing with.

p.s.  If you are thinking about getting into hunting for edibles, remember to only eat mushrooms that you have identified absolutely positively. A good resource for local mushroom hunting and education in general is the Colorado Mycological Society, who have expert-guided forays to help safely hunt and enjoy wild mushrooms.

References 

1. Stucky Evenson, V. (2015). Mushrooms of the Rocky Mountain Region. Portland, OR: Timber Press. 
2. Arora, D. (1986). Mushrooms Demystified. Berkeley, CA: Ten Speed Press. 
3. Ascomycota (n.d.) Retrieved from Wikipedia on November 11, 2015: https://en.wikipedia.org/wiki/Ascomycota