Pick a Prickly Pear

Note About Lichens and Star Wars

     Although this post will look at cacti in Colorado, I noted something in the new Star Wars movie that was relevant to this blog. In the final scene of Star Wars: The Force Awakens, brilliant orange lichens are clearly visible splashed across the rocks where the scene was shot. This is probably Xanthoria elegans or a related species, which were addressed in depth in a previous post. My hope is that those of you who have watched or will be watching the movie will look out for this detail and revel in the knowledge that your Star Wars viewing experience was enhanced by the glorious beauty of parietin-producing lichens. May the force be with you, readers! 

    

Colorado Cacti 

     While Colorado supports a wide range of climate zones, much of the state falls into the classification of semi-arid land dominated by brush and grasses(1). This is the ecosystem seen in the foothills, the eastern plains, and many desert-like parts of the state such as the San Luis Valley and parts of the Colorado plateau near Grand Junction. Cacti thrive in semi-arid climates, although those which grow in Colorado tend to be smaller and lower-growing than their impressive cousins such as the the saguaro of the Sonoran desert. 

      Cacti (Cactaceae) are an easily recognizable family of plants which in many cases have exchanged their leaves for prominent spines, with photosynthesis taking place in the succulent stems(2). The outer skin of a cactus is an impermeable, waxy cuticle which helps cacti to retain water in arid environments. While some plant families require patient observation to recognize in the field, most people know a cactus when they see one. It's always fun to encounter a well-fortified cactus growing alongside the trail, sometimes with showy flowers. Cacti tend to flower in the spring, and the cacti of Colorado produce impressively large colorful blooms relative to their size. 

     Flower guides for Colorado seem to snub cacti. This may be because despite their impressive flowers, many native cacti are relatively small, may not flower in large patches, and blend well with the soil when not in bloom. The two print references I typically use(3,4) only make a nod to the genus Opuntia without delineating species, while leaving other genera unexplored. This excellent site(5) notes five genera with ten species, but since it focuses on the four corners area it is possible that more cacti are represented than those which grow only within Colorado. At worst, the several native cactus species of Colorado are not difficult to learn to differentiate when considered in context some other plant families prominent in the region. Asteraceae, for instance, has hundreds of species in the Rocky Mountain region (7), most of which look infuriatingly similar. An intriguing density gradient map of plant species diversity which includes both Asteraceae and Cactaceae may be found here. 

     For the purposes of this post, I am going to focus on four species of cacti that I have encountered in traveling about the state. These are Opuntia macrorhiza, Opuntia polyacantha, Pediocactus simpsonii, and Escobaria vivipara. 

Opuntia macrorhiza, Pricklypear Cactus  

     O. macrorhiza is one of two pricklypear species found in CO. All Opuntia species are readily recognized for their patches of spines and flattened, green pads. I have encountered both Colorado species up to at least 7,000 feet of altitude in a variety of climates, although they seem to be most abundant in sunny dry areas. O. macrorhiza differs from O. polyacantha in its tendency to have longer spines growing from its areoles, larger pads, diminished spines towards the basal end of the pad, and occasional lateral creases of the pad flesh. The flowers of both species look highly similar and may be a range of colors including pink, yellow, peach, or even red. 

     All species of Opuntia that I am aware of are supposed to be good edibles, with the fruit providing a good base for jellies while the de-spined pads may be grilled or boiled as a green vegetable(8). 

O. macrorhiza growing in canyons near Colorado National Monument. 

Note the length of the spines.

New growth on O. macrorhiza. The pink structures appear to be still-living 

leaf primordia from which the hard, lifeless spines will eventually be produced.  

O. macrorhiza growing on North Table Mountain near Golden. The ID for this image was  based on the 

presence of longer spines more distally on the pad, with their presence diminishing towards the base.

Fruit on an Opuntia cactus, likely O. macrorhiza evidenced by the lateral creases 

and more pronounced spines more distal on the pad. This particular cactus was growing 

outside of an office park along the Cherry Creek in Denver. 

Opuntia polyacantha, (also) Pricklypear Cactus  

     

     The common name for this cactus does not differentiate it from its closely related cousin mentioned above. Both species of Opuntia in Colorado are simply referred to as a pricklypears. O. polyacantha looks highly similar to O. macrorhiza in most regards, and is equally edible. The main differences to look for are the slightly smaller pads, consistent presence of spines on the pad from top to base, and the shorter spines(9). The lateral creases mentioned as characteristics of O. macrorhiza are not indicated in sources that I can find as field characters of O. polyacantha, so it appears that horizontal wrinkles are a good indicator that a pricklypear is not O. polyacantha. 

Opuntia polyacantha in bloom on North Table Mountain near Golden. I made this ID solely on 

the basis of the consistent, closely spaced spines up and down the pad. 

Pediocactus simpsonii, Simpson's Pincushion Cactus 

     P. simpsonii is a squat, barrel-shaped cactus that inhabits sunny, rocky slopes in the foothills. The genus Pediocactus is populated by squat, barrel-shaped cacti(10). The lumpy swells below each areole are called tubercles, and Pediocacti have pronounced tubercles which may become more rib-like (vertically aligned and uniform) with age. Areoles are often woolly with trichomes and short, plentiful spines. Flowers tend to be funnel-shaped, and to bear scales (short sepals) on the outside of the petals. Cacti in this genus are frequently referred to as hedgehog or pincushion cacti for obvious reasons, although some other cacti may also be referred to by these common names. 

     All of these features apply nicely to P. simpsonii, and are visible in the photos below. This cactus is easily missed as it is not very large: only a few inches in diameter and growing even less tall. Look for it in sunny, South-facing exposures in the foothills. Its appearance can be quite variable with more tightly or closely spaced tubercles, tiny to largish stems depending upon age, and flowers which may be white, yellow, or even green(11). The spines grow radially from each tubercle, with a central spine(s) which may be black or brown. It may be quite small (>3 inches in diameter) as in the photos below, and ranges up to about 7 inches in diameter. 

     P. simpsonii is named in honor of James H. Simpson, an army engineer who led an expedition in Colorado(12). 

Pediocactus simpsonii crouching between some rocks on North Table Mountain. The yellow-green, 

fleshy flowers are easy to miss amidst the hot rocks and straw-colored brush that mark their habitat.

Same cactus, different angle. Note the relative size of the blades of grass (unidentified) in the  background of the photo. This particular individual is not large, with the stem spanning only a few inches in diameter. 

Escobaria vivipara, Common Beehive Cactus 

     E. vivipara is a widely distributed cactus, ranging from Canada to Texas(13). It enjoys the same arid, sunny habitats characteristic of other cacti in Colorado. E. vivipara demonstrates the marks of the genus Escobaria nicely. These include squat, rotund habit, and spines which grow from tubercles(14). You could be forgiven for confusing members of this genus with those of Pediocactus, as these and many other genera of stout cacti are best distinguished by very minute features of the flowers and seeds. 

     Adding to the confusion, both P. simpsonii and E. vivipara bear short, radial spines of which the primary (more central) spines are brown to black. However, E. vivipara has grooved tubercles, which give them a more polygonal appearance than those of P. simpsonii. I also have not been able to find any reference to P. simpsonii ever bearing pink/rose flowers, while E vivipara consistently does, which may honestly be the most useful field mark for a casual cactus enthusiast in this area.  

     One final feature of interest for E. vivipara is the density of its spines, which may be adapted to not only prevent predation by herbivores as in the previous species mentioned in this post, but also to provide shade to the cactus stem in sunny environments. I have not been able to find any specific reference to whether the spines of E. vivipara provide this function or not, but species with similarly dense, radial spines often benefit from the additional shade(15). 

Escobaria vivipara growing at about 6,500 ft in the foothills near Denver. 

Note the angular tubercles and the brilliantly pink flowers. 

     Thank you for reading about the small, spiky wonders of cacti! It was an educational post to research and I hope it was informative. I also hope that everyone who sees this has as pleasant a Christmas as I did while I worked on finishing this: quietly typing away while drinking wine and watching a spy movie with my family. Stay warm and Happy Holidays!

References 

1. Colorado. (n.d.). Retrieved from Wikipedia: https://en.wikipedia.org/wiki/Colorado#Eastern_Plains
2. Cactaceae. (n.d.) Retrieved from Wikipedia: https://en.wikipedia.org/wiki/Cactus 
3. Mammoser, D., & Tekiela, S. (2007). Wildflowers of Colorado. Cambridge, Minnesota: Adventure Publications, Inc.
4. Craighead, J. J., Craighead., F. C., & Davis, R. J. (1963). A Field Guide to Rocky Mountain Wildflowers. Boston, MA: Houghton Mifflin Company.
5. Schneider, A. (n.d.) Wildflowers, ferns, and trees of Colorado, New Mexico, Arizona, and Utah. Retrieved from: http://www.swcoloradowildflowers.com/index.htm 
6. Easter Colorado Wildflowers (n.d.). Opuntia macrorhiza. Retrieved from: http://www.easterncoloradowildflowers.com/Opuntia_macrorhiza.htm 
7. Kartesz, J.T., The Biota of North America Program (BONAP). 2015. North American Plant Atlas. (http://bonap.net/napa). Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)].
8. Missouri Botanical Garden (n.d.) Opuntia macrorhiza. Retrieved from: http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=a248 
9. Eastern Colorado Wildflowers (n.d.). Opuntia polyacantha. Retrieved from http://www.easterncoloradowildflowers.com/_c_3frame.htm 
10. Tomlinson, N., & Robinson, W.(2008). ECHINOPSIS. Retrieved using Internet Wayback Machine from:http://web.archive.org/web/20080720010527/http://cssaustralia.org.au/content/view/72/104/
11. Schneider, A. (n.d.). Pediocactus simpsonii. Retrieved from: http://www.swcoloradowildflowers.com/White%20Enlarged%20Photo%20Pages/pediocactus%20simpsonii.htm   . 
12. Cactus Art Nursery (n.d.) Pediocactus Simpsonii. Retrieved from: http://www.cactus-art.biz/schede/PEDIOCACTUS/Pediocactus_simpsoni/Pediocactus_simpsonii/pediocactus_simpsonii.htm 
13. United States Department of Agriculture [USDA]. (n.d.). Escobaria vivipara (Nutt.). Retrieved from: http://plants.usda.gov/core/profile?symbol=ESVIV 
14. Cactiguide.com (n.d.). Genus: Escobaria. Retrieved from:http://cactiguide.com/cactus/?genus=Escobaria 
15. Mauseth, J. (n.d.). Cactus spines. Retrieved from: http://www.sbs.utexas.edu/mauseth/researchoncacti/spines.htm 

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 

Painted Rocks: The Orange Lichens

     One of the more striking experiences with lichens anyone is likely to have in Colorado is encountering splashes of DayGlo orange or chartreuse on an otherwise brown, black, and green lichenized rock face. This post explores tricks for identifying down to the genus level what species of shockingly orange lichen you may have encountered, and some interesting facts about them as well. The genera of interest are Xanthoria/Xanthomendoza and Caloplaca. 

Xanthoria/Xanthomendoza (orange) species, possibly X. elegans, growing on Pike's Peak granite. The violent coloration can be missed due to the small size of the thalli: the larger crystals in this picture are not more than 1cm across. The brilliantly yellow-green lichen is Pleopsidium flavum, which I will look at in a future post.

Xanthoria/Xanthomendoza vs. Caloplaca 

     Orange lichens that you encounter in Colorado belong one of two (now three) genera. The genera of Xanthoria/Xanthomendoza discussed below represent eight species, while Caloplaca weighs in at a whopping 54 species. Not all species in these genera are orange, but all orange species in Colorado belong to these genera, and all of them owe their orange coloration to the same remarkable pigment: parietin(1). Parietin functions to protect the lichen from UV radiation(2) and to chemically beat down competing microorganisms on the rock surface(3). It has also demonstrated some weak anti-cancer properties in being able to induce apoptosis in certain cell lines, but not as well as some other lichen secondary metabolites(4). Parietin holds its color well after the death of the lichen, and some people use it for dying(5). From a lichen identification perspective, a spot test using a solution of potassium hydroxide will yield a brilliant purple color in the presence of parietin(1). This doesn't help to differentiate between any of Colorado's orange genera as they all have the same primary pigment, but it can be handy for other genera. A good photo of a KOH spot-test can be found here (scroll down for image). 

     Note that I have been separating Xanthoria and Xanthomendoza genera from each other. All Xanthomendozae used to be classified under Xanthoria, until it was noticed that the two bear different conidia, and that those which became Xanthomendoza have either rhizenes or other holdfasts while Xanthoria do not(6). Other than those differences, the two genera look essentially the same. 

     If color is of no use, how then to differentiate Xanthoria/Xanthomendoza ssp. from Caloplaca ssp.? All three genera belong to the same family, Teloschistaceae(7). All three genera have many species which tend to be orange, and may grow on rocks or on bark. The species with orange thalli all have rounded, cup-shaped lecanorine apothecia(6,8). The best feature to distinguish between Caloplaca and Xanthoria/Xanthomendoza ssp. appears to be the habit of the thallus: Xanthoria and Xanthomendoza ssp. tend to have foliose thalli(9), while Caloplaca ssp. tend to be crustose or occasionally fruticose(9,8). A wikipedia page which does not cite its source for the information also notes that Xanthoria ssp. may be squamulose(9). 

     In practice this means that an orange lichen which can be cleanly separated from its substrate with a knife blade probably belongs to Xanthoria or Xanthomendoza, while orange lichens which cling tenaciously to their substrates and do not have a lower cortex (which may be a different color than the thallus) are more likely to be Caloplaca ssp. This is hardly a foolproof test, however, since squamulose lichens also do not have a lower cortex, and since some Caloplaca ssp. such as Caloplaca coralloides have such tightly bound fruticose structures as to appear crustose(8). Also, based on my own observations of photos of each genus, it seems that Xanthoria/Xanthomendoza lichens tend to have a more flowing, consistent thallus while the thalli of Caloplaca ssp. tend to be more warty, fissured, or grainy. Below are some pictures of lichens that I'm pretty sure I have identified correctly from each genus. Click image to enlarge. 

Genus Caloplaca

Caloplaca trachyphylla growing on sandstone in the Utah desert. This lichen almost always grows on sandstone, and forms beautiful, prominent rosettes like this one. The crustose habit and "warty" thallus help to separate it from Xanthoria elegans. 

A close-up of C. trachyphylla. Note how the lecanorine apothecia become more flattened and even convex towards the thallus' center. The white growth toward the top center-left may be the beginnings of a colony of Acarospora stapfiana, another lichen which is parasitic on C. tracyphylla.

Caloplaca arenaria, also growing on sandstone. The salient parietin-bearing structures in this picture are actually the apothecia. This species often has a near non-existent thallus, which if present is gray(12). The black, blurry marks at left are millimeters.  Seen on the macro scale this species appears as tiny, blood-red granules.

Genus Xanthoria 

   

Xanthoria elegans growing on Pike's Peak granite with an unidentified gray foliose lichen. X. elegans may form more rosette-like structures, but this admittedly blurry photo does a nice job showing its more flowing structure.  

If you see vertical streaks of orange like this on rocks, odds are you're dealing with X. elegans. It enjoys drainage channels and seeps that come off of nitrogen-rich cracks in rocks where rodents or birds habitually poop(1). The purple flowers barely visible in this photo are the relatively rare wildflower Boykinia jamesii, which grows in abundance in the Crags area on the West side of Pike's Peak.

 

Genus Xanthomendoza 

A magnified view of a Xanthomendoza species I found on the wooden fence in my back yard. I'm not certain on the ID, but it appears to be either Xanthomendoza ulophyllodes or Xanthomendoza fulva. The presence of apothecia seems to indicate Xanthomendoza ulophyllodes.

Xanthomendoza montana growing on an exposed rock face on Mount Evans. As best I can tell, X. montana is best differentiated from Xanthoria elegans by its more lumpy, mounded habit. 

Xanthomendoza montana growing in luxuriant lumps near the summit of Mount Evans. The thallus can hardly be seen through the prolific apothecia. 

Xanthomendoza montana growing on granite at approx. 12.000 ft. The white flowers are Minuartia macrantha, the alpine sandwort. 

     Thank you for reading about orange lichens! Think of them as you enjoy your orange Thanksgiving foods such as Ipomoea batatas, although in that case the orange pigments are carotenoids, not parietins. 

References

1. Corbridge, J. N., & Weber, W. A. (1998). A Colorado Lichen Primer. Niwot, CO: University Press of Colorado.
2. Nybakken, L., Solhaug, K. A., Bilger, W., & Gauslaa, Y. (2004). The lichens Xanthoria elegans and Cetraria islandica maintain a high protection against UV-B radiation in Arctic habitats. Oecologia, 140(2), 211-216. doi:10.1007/s00442-004-1583-6
3. Gazzano, C., Favero-Longo, S. E., Iacomussi, P., & Piervittori, R. (2013). Biocidal effect of lichen secondary metabolites against rock-dwelling microcolonial fungi, cyanobacteria and green algae. International Biodeterioration & Biodegradation, 84300-306. doi:10.1016/j.ibiod.2012.05.033
4. Bačkorová, M., Jendželovský, R., Kello, M., Bačkor, M., Mikeš, J., & Fedoročko, P. (2012). Lichen secondary metabolites are responsible for induction of apoptosis in HT-29 and A2780 human cancer cell lines. Toxicology In Vitro, 26(3), 462-468. doi:10.1016/j.tiv.2012.01.017
5. Mycopigments (2013). Lichen dyes [web log post]. Retrieved from http://mycopigments.com/lichen-dyes/
6. Sharnoff, S. (2014). Field Guide to California Lichens. New Haven, CT: Yale University Press.
7. KARNEFELT, I. (1989). MORPHOLOGY AND PHYLOGENY IN THE TELOSCHISTALES. Cryptogamic Botany, 1(2), 147-203.
8. Kelso, M. (2005). Caloplaca coralloides. Retrieved from: http://www.mbari.org/staff/conn/botany/lichens/taxonomy.htm
9. Wade, A. E. (1965). The genus Caloplaca th. fr. in the British Isles. The Lichenologist: 3(1), pp. 1-28. DOI: http://dx.doi.org/10.1017/S0024282965000038  
10. Xanthoria (n.d.) [article entry in wiki]. Retrieved from: https://en.wikipedia.org/wiki/Xanthoria
11. Consortium of North American Lichen Herbaria [CNALH](n.d.) Colorado. Retrieved from: http://lichenportal.org/portal/checklists/checklist.php?pagenumber=2&cl=1202&dynclid=0&pid=510&searchsynonyms=1
12. Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.)(2001). Lichen Flora of the Greater Sonoran Desert Region. Vol 3. Tempe, AZ. Retrieved from: http://lichenportal.org/portal/taxa/index.php?taxauthid=1&taxon=56217&cl=1202