Fungus Fact Friday


#235: Developmental Mycology

Developmental biology focuses on the question, “How do organisms start out as a single cell and then become large complicated structures with distinct tissues, shapes, and sizes?” In the context of mycology, studying development means researching the formation of structures such as mushrooms, sclerotia, and rhizomorphs. Not surprisingly, most developmental mycology research focuses on mushrooms, which are the largest and most interesting of the complex structures formed by fungi. In my previous post (FFF#234), I summarized what we know about mushroom development. Today, I will go into more detail on the mechanisms and processes that drive fruitbody development.

Amanita muscaria development 2

#234: Mushroom Development

My first introduction to mushrooms was as a child seeing them appear as if by magic in my family’s lawn. This mysterious way that fungi appear to pop into existence still captures my imagination, which brought me to the small but interesting field of mushroom development. So, can science explain how mushrooms appear out of thin air? Mostly, but there is still much we don’t know. Obviously, mushrooms don’t materialize out of nothing – instead, they sprout from the mycelium already growing in the substrate. Typically, this proceeds as follows: the mycelium bunches up, then the various mushroom tissues are created, and finally whole fruitbody gets larger. However, this generalized model has limitations and can’t explain all the variation we see in mushroom shapes. Why Study Mushroom Development? Before we get into the details, it is useful to discuss why mushroom development should be studied. One of the major reasons...


#011: Characteristics of Fungi

What is a fungus?  That question has been answered many ways over the years, reflecting an evolving understanding of this strange group of organisms.  Initially, fungi were classified as a class in kingdom Plantae.  As our understanding of the chemistry, life history, and evolution of fungi improved, Fungi was elevated to the rank of kingdom.  Kingdom Fungi is placed in domain Eukarya and belongs to the major clade Opisthokonta.  Opisthokonta also includes the kingdom Animalia, which makes animals close relatives of the fungi.  But going beyond taxonomic definitions, what makes a fungus a fungus?  It’s hard to answer that question because the fungal kingdom is very diverse and there are many similar organisms in other kingdoms.  As a simple answer, Fungi are heterotrophic filamentous (or unicellular) eukaryotes with a chitin cell wall that reproduce by spores and digest their food externally.


#019: Apiosporina morbosa, Black Knot

And now for something completely different: how to recognize different types of trees from quite a long way away.*  Black Cherry (Prunus serotina) is the easiest tree in eastern North America to identify, thanks to the fungus Apiosporina morbosa, commonly known as Black Knot.  Most Black Cherry trees are infected with A. morbosa, which causes dark swellings on branches and trunks.  Older tree trunks are often marred by large swellings caused by A. morbosa that are up to twice the size of the trunk.  These “knots” are easy to spot from a distance (especially in winter), so take advantage of this and amaze your friends by pointing out Black Cherry trees without relying on bark, leaves, or other details!  On twigs and smaller branches, Black Knot makes the branches lumpy and thickened in places, looking remarkably like “dried cat poop on a stick” (thank Michael Kuo for that apt analogy).

Phleogena faginea on oak bark 0

#233: Phleogena faginea

Phleogena faginea is a bizarre little mushroom. This tiny grey-brown mushroom grows on wood or bark, making it rather difficult to spot. Even when you do find it, you’d probably think it’s a slime mold (FFF#053): the fruitbody features a round head on a small stalk, much like many slime molds. Despite that similarity, P. faginea is a basidiomycete and its closest relatives are the rust fungi (FFF#130) – something you probably wouldn’t guess by looking at the mushroom. P. faginea goes by the common name of “Fenugreek Stalkball,” which is a reference to its shape (ball on a stalk) and fenugreek or curry-like odor when dried.

Gyromitra brunnea 0

#232: Gyromitra brunnea

Gyromitra brunnea is a false morel (see FFF#034) that is fairly common in the eastern and midwestern parts of North America. Like the other false morels, it has a solid to chambered stipe and a wrinkly head. The thing that sets G. brunnea apart, however, is that the cap is highly lobed and there are white seams along the edges of the lobes. No other false morels feature these seams, making G. brunnea easy to identify.


#067: Mushroom Morpholgy: Verpas

The genus Verpa contains just a handful of species that are encountered occasionally.  These mushrooms look a lot like morels (FFF#033), but are attached just at the top of the cap and have a stipe filled with cottony material.  The cap of a verpa hangs down around the stipe, rather like a thimble on top of a finger.  This arrangement has led to the common names “Thimble Cap” or “Thimble Fungus,” although I usually just call them “verpas.”  Verpas tend to appear just before morels, so if you find one you should come back to check for morels after a week or two.


#231: Hypholoma tuberosum

I first saw this mushroom in 2017 at a foray in Pennsylvania.  There wasn’t much out, so six of us spent a lot of time trying to identify these little brown mushrooms growing in mulch right outside the foray center.  We ruled out everything in our keys and couldn’t nail down the species until we found sclerotia growing below the mushrooms.  As it turns out, the sclerotia are the only interesting feature of these LBMs.  Brown cap, brown stalk, dark spores, small, growing in mulch – this description could apply to hundreds of mushrooms until you get into the nitty-gritty details.  Fortunately, you can easily separate these mushrooms from similar ones by looking for the sclerotia.


#230: Lichenomphalia umbellifera

Nearly all lichens belong to the Ascomycota, but there are some lichenized basidiomycetes (often called “basidiolichens”)… and a few of those actually form mushrooms!  Lichenomphalia umbellifera is a lichen that forms a small agaric.  If you find this mushroom, you would probably dismiss it as just another LBM, unless you notice the lichen at its base.  The lichen part of this mushroom consists of tiny green bubbles that seem to be sprinkled over its substrate.  You’re most likely to find L. umbellifera in the Pacific Northwest – just remember not to overlook the small mushrooms!

Buglossoporus quercinus 4

#229: Buglossoporus quercinus

Buglossoporus quercinus is an interesting polypore that most of you probably haven’t seen before.  I’ve seen it only once, myself, brought in at a mushroom club meeting.  It reminds me of a yellow version of Ischnoderma resinosum.  B. quercinus forms brackets that are fuzzy yellow on top with a white pore surface below.  All parts of the mushroom stain brown when handled.  The coloration and staining make it a unique mushroom.  The Global Fungal Red List Initiative lists B. quercinus as “vulnerable” because it is rarely found and grows on only old oak trees – a habitat that is in decline across Europe.  Although B. quercinus is primarily known from Europe, it was recently discovered growing in eastern North America.