When Mushrooms Grow Hair: Spinellus and Syzygites megalocarpus

Spinellus fusiger parasitizes Mycena species, like this M. haematopus.

Spinellus fusiger

Though it's hot as stink outside right now, and dry, to boot, most of this summer has been unseasonably cool and moist—perfect growing conditions for all kinds of interesting fungal fruitings, including one I've wanted to see for years, Spinellus fusiger. The weather has, in fact, been so accommodating that I've found this spectacular bread-mould-related growth four separate times. It's hard to care about how crummy the weather is for swimming when hair-raising characters like this keep appearing in the woods.

The long, erect sporangiophores of Spinellus fusiger make the
mushrooms they attack look as if they've been electrocuted.

Spinellus species are parasites that attack your basic mushroom-looking mushroom, and are, in my humble opinion, wonderfully photogenic. The most common in these parts, S. fusiger, prefers Mycena species as its victims, often M. haematopus, which, even when its cap is sprouting a crazy new fungal hair-do, can still be identified by snapping its stem to look for its characteristic "blood."

Spinellus species grow long erect "sporangiophores" tipped by 

spherical spore-producing bodies that darken as spores mature.

Mucorales

Spinellus species belong to the order Mucorales, or "pin molds," in the phylum Zygomycota. The hyphae of these fungi, unlike those of ascomycetes or basidiomycetes, are rarely septate, which means they have no barriers to slow the movement of cytoplasm, allowing them to grow extremely quickly. If you've ever had a loaf of bread that's been colonized by the less spectacular, but much more common mucorale, Rhizopus stolonifer, or black bread mould, you will understand how quickly these fungi can grow.  

Hundreds of asexual Spinellus spores are produced by each sporangium. 

All mucorales produce spores in tiny globose sporangia held at the tips of sometimes very long specialized hyphae called sporangiophores. Though mucorales are capable of reproducing both sexually and asexually, the vast majority of spores are anamorphic, or asexual. 

The stalks of Spinellus, and all other mucorales, 
have a swelling at the tip called a columella.

The balloon-like columellae persist after spore dispersal.

Syzygites megalocarpes

Another woodland mycoparasitic mucorale, is Syzygites megalocarpus. The only species in its genus, S. megalocarpus is nowhere near as choosy about its victims as S. fusiger and has, so far, been found on 65 different genera. It's easily recognized by its multi-branched sporangiophores that make the fungi they parasitize look as if they've not only grown hair, but hair that desperately needs frizz-control. When they first start growing, these sporangiophores are deep yellow due to the carotenoid pigments they produce, but become paler as they stretch out, and eventually turn a more traditional mould colour—bluish gray. 

This Syzygites has made an Amanita flavoconia almost unrecognizable.

This Syzygites megalocarpus appeared overnight on a
Boletus subvelutipes left out on my dining-room table.

An ethereal veil of Syzygites megalocarpus hangs 
from the cap of a small Pluteus species.

Though I've found S. megalocarpus a number of times, they've always either been past their prime or I've been without camera, so I had no usable in situ photographs for this post. Ever the optimist, though, I went out in search of one a few days ago, before this heat wave hit, and—lucky me!—I found a beauty in full glory that had infested a Pluteus growing picturesquely on a log. 

The sporangiophores of Syzygites megalocarpus are 
dichotomously branched up to six times. 

Asexual spores of Syzygites megalocarpus are 
produced on the tips of branched sporangiophores.

So what does a cold summer have to do with finding Spinellus fusiger for the first time? Well, it turns out that Spinellus species, as well as S. megalocarpus, are temperature sensitive, with a distinct preference for cooler weather. Spinellus are the pickiest, requiring temperatures to be lower than 22ºC to grow. I don't know about where you live, but summers here in Ontario have become so consistently hot over the past twenty years that a high of 22ºC has come to be considered "cold." Is it coincidence that, though I'd never come across it before, I stumbled upon Spinellus four separate times this season? I doubt it. And because I doubt it, I'm adding the previous dearth of Spinellus to my growing list of local anecdotal evidence that fungi fructifications are being affected by climate change.   



References:

Syzygites megalocarpus on Mycoquebec
Spinellus fusiger on Mycoquebec
Zygomycota
Mucorales
McLaughlin, D. J., E. G. McLaughlin, and P. A. Lemke. 2001. The Mycota VIIA: Systematics and Evolution. Springer-Verlag, New York.  
Hoffmann, K., Pawlowska, J., Walther, G., Wrzosek, M., de Hoog, G. S., Benny, G. L., ... & Voigt, K. (2013) The family structure of the Mucorales: a synoptic revision based on comprehensive multigene-genealogies. Persoonia 30: 57-76.


Fun: 
Time-lapse video of Syzygites growing

Read It and Weep: Fungal Guttation

Young Fomitopsis pinicola with guttation drops (click to see bigger)

Some fungi are prone to exhibiting a curious phenomenon—they exude beads of moisture, called guttation. In several polypores, such as Fomitopsis pinicola, the liquid produced can look so much like tears that you'd swear the fungus was weeping. Or maybe sweating. Other species produce pigmented drops that can look like milk, or tar, or even blood.

Guttation is more well-known in some vascular plants. During the night, when the plant's transpiration system is shut down, pressure from excess moisture in the roots can force beads of sap out of special structures on leaf edges. 

Guttation droplets on strawberry leaves (Noah Erhardt/Wikipedia)

In fungi, the guttation mechanism is not so well understood. In many species, however, it's so often observed, particularly during times of rapid growth when temperature and humidity are favourable, that these beads of liquid can be a reliable macroscopic characteristic. Hydnellum peckii, for instance, so frequently "bleeds" pigmented drops in its early stages of growth that it's been given gruesome nicknames, including "Bleeding Tooth Fungus" and "Devil's Tooth." Coincidentally, a 1965 study found a compound in the fruiting body of  H. peckii that has anticoagulant properties similar to those of heparin, too much of which can make one bleed to death internally.   

Producing blood-like guttation droplets during periods of rapid growth is 
a well-known characteristic of Hydnellum peckii. (Lisa Neighbour)

Young fruit bodies of Fomitopsis pinicola commonly produce copious guttation.

A few weeks ago, I came across a crop of Inonotus glomeratus on a maple log. I've found this amazing polypore a few times, once right after it had showered itself, and everything else around it, with what I assumed were millions of sulphur-yellow spores. The one I found this summer, though, was very young, and instead of spewing spores, it was weeping globules of "tar" in copious enough amounts that shiny black pools were accumulating on the forest floor. Unlike most guttation drops, which are watery, these exudations were thick and sticky and stained my finger and thumb a deep auburn brown. And kind of glued them together. Oddly, though this unusual guttation has been noted by others, there seems to be no mention of it in the literature. I. glomeratus is so unusual in so many ways, I've written a whole post about it.

Fast-growing Inonotus glomeratus produces tarry guttation.

This Inonotus glomeratus continued to drip its viscous black exudate
even after it began releasing its yellow spores.

The guttation drops on this Inonotus glomeratus were so thick that the fungus grew
around them, producing a pitted appearance after rain washed them away.

Polypores and Hydnoids are not the only fungi to produce guttation. In moist conditions, young Suillus americanus stipes can be heavy with yellow-tinted drops. Guttation is also common enough in the uncommon Rhodotus palmatus that this characteristic is often included in descriptions. 

Suillus americanus (above) and Rhodotus palmatus (below) 

Guttation can happen in incredibly small ways, too. During the Toronto Bioblitz this past spring, we found some Lachnum subvirgineum that, despite what seemed like dry conditions, were covered in minute guttation droplets, as were most other Lachnum I've since come across. 

The largest of these Lachnum subvirgineum was less than .5 mm. in 

diameter, which makes the guttation droplets impressively small.

Just yesterday I found another ascomycete sporting the same clear drops—this time Incrucipulum ciliare, whose hair-rimmed discs are even smaller than L. subvirgineum, hence, so, too, were its guttation droplets.

The guttation droplets on these Incrucipulum ciliare were almost too small for 
my camera to capture. The "stick" in the lower right corner is an oak leaf vein. 

Another minute character is so characteristically bejewelled in guttation droplets, it's named for it: Pilobolus crystallinus, which is one of the "Cannon" or "Hat Thrower" fungi found on herbivore dung.

Pilobilus crystallinus is named for its sparkling
guttation droplets. (Keisotya/Wikipedia)

Though little is known about guttation in wild fruiting bodies of fungi, it's a common phenomenon of fungal mycelia and hyphae in the lab, and a number of studies have been done to determine what the exudates contain. Penicillin has been found in the guttation droplets produced by Penicillium species in similar concentrations to that found in the culture broth, while gliotoxin, which has immunosuppressive qualities, has been found in guttation droplets of Aspergillus fumigatus. Do these fungi use guttation droplets as reservoirs for metabolic byproducts, or do they simply use them for water storage? 

Or have different species evolved to produce guttation droplets for different purposes? The edible bolete, Suillus bovinus, for instance, has been shown in the lab to reabsorb nutrients from its guttation droplets, while leaving behind less useful byproducts, such as oxalic acid. So perhaps guttation has evolved as an efficient method of expelling waste for some fungi. 

Is that what's going on with Inonotus glomeratus? Is that viscous, black ooze just a collection of rejected metabolic byproducts? If anyone would like to analyze it and has the means, I have some dehydrated exudate that I'd love to send you!  

Even some slime moulds, like this immature Stemonitis 
flavogenita, produce guttation droplets. (Ulrike Kullik) 

Pink-pored Fomitopsis rosea are even prettier when 

decorated with shimmering beads of moisture. I think the 
pattern on rim was made by the teeth of a grazing slug.

Punctularia strigosozonata "bleeds" rust-tinted droplets.

Early nubbins of an unidentified polypore exude milky drops.

This Fomitopsis pinicola produced guttation droplets for three
months this summer. When it finally stopped, trompe l'oeil
teardrop-shaped indentations were left behind.

Wet weather makes Xylaria hypoxylon produce beads of moisture.

This large Pleurotus dryinus was weeping copiously
despite there having been no rain  for a week.

Many parasitic Hypomyces, such as this H. chrysospermus, are prolific weepers. 

Inonotus dryadeus is a lumpy polypore known for its ample
 production of amber guttation droplets. (Wikipedia)

Selected References:

Erast Parmasto, Andrus Voitk, (2010). Why Do Mushrooms Weep? Fungi, Vol. 3:4
N.B. In my original post, relying on the above article, I had repeated that Fomitopsis pinicola does not produce guttation drops in Newfoundland. Andrus Voitk has since kindly informed me that, in fact, they regularly do, as he notes in Omphalina Vol. III, No. 3. 

Hutwimmer, S., Wang, H., Strasser, H., Burgstaller, W. (2010) Formation of exudate droplets by Metarhizium anisopliae and the presence of destruxins. Mycologia, Vol. 102 no. 1, 1-10

Gerhard Saueracker. On the Exudates of Polypore Fungi. Fungimap Newsletter 48, Jan. 2013