Fairy Umbrellas

Here's a familiar little critter:

Umbrella Inky-cap (Parasola plicatilis), Ryerson FP, Lake Co, IL 9/29/2011

Well, it's familiar if you like looking real closely at lawns. This is an Umbrella Inky-Cap (Parasola plicatilis), a common lawn mushroom in much of the country.

What we call a mushroom is actually just the reproductive structure of a fungus (of some fungi, at least). The majority of the fungus is a mass of thread-like cells called hyphae that extend, in this case, into the soil. They're rather hard to distinguish from each other this way, of course, so we generally use the mushroom characteristics to identify the fungi. Modern DNA and chemical analyses are proving that to be a good way to grossly underestimate fungal diversity, though. (1)

But why do the mushrooms differ so widely? This is a difficult question -- all a mushroom should have to do, it seems, is to disperse as many spores as it can as widely as possible without being eaten first. There seems to be an awful lot of structural diversity for such simple functions. Bright colors may well be aposomatic, but what is the functional significance of a scaly versus a smooth top to a mushroom, when the spores are produced on the underside?

Nagy, et al. have looked at this question with regards to the Parasola shown above, as well as related species. This one, as well as many others in the family Psathyrellaceae, exhibit a phenomenon known as deliquescence -- the gills on the underside dissolve into an inky liquid as the spores mature. (Hence the name Inky-caps.) Using the family and the evolution of deliquescence as a platform for testing recently developed statistical techniques for phylogenetic analysis, they found multiple origins for this trait, and found no support for its loss in any lineage. (2) Apparently deliquescence produces some sort of notable advantage for those lineages that develop it. They also found that certain structures on these mushrooms appear to have co-evolved with the emergence of deliquescence, suggesting some form of functional significance to them as well. (3) They suggest that it's a way of avoiding desiccation of the spores, which is an interesting hypothesis that appears to need testing. Whether or not avoiding desiccation is the primary function, this process appears to have driven a rapid adaptive radiation in the family, along with some correlated structures that serve to protect the spores from predators. (4)

Parasola isn't, as far as we know, edible, and it doesn't cause infections. It doesn't appear to be poisonous, or damage anything we find useful. In the words of Leopold, "Just a small creature that does a small job quickly and well."



(1) Nagy, L. G., Desjardin, D. E., Vágvölgyi, C., Kemp, R., & Papp, T. (2013). Phylogenetic analyses of Coprinopsis sections Lanatuli and Atramentarii identify multiple species within morphologically defined taxa. Mycologia, 105(1), 112-124.

(2) Nagy, L. G., Urban, A., Örstadius, L., Papp, T., Larsson, E., & Vágvölgyi, C. (2010). The evolution of autodigestion in the mushroom family Psathyrellaceae (Agaricales) inferred from Maximum Likelihood and Bayesian methods.Molecular phylogenetics and evolution, 57(3), 1037-1048.

(3) Nagy, L. G., Walther, G., Hazi, J. U. D. I. T., Vágvölgyi, C., & Papp, T. (2011). Understanding the evolutionary processes of fungal fruiting bodies: correlated evolution and divergence times in the Psathyrellaceae. Systematic biology,60(3), 303-317.

(4) Nagy, L. G., Hazi, J. U. D. I. T., Szappanos, B., Kocsubé, S., Bálint, B., Rakhely, G., ... & Papp, T. (2012). The evolution of defense mechanisms correlate with the explosive diversification of autodigesting Coprinellus mushrooms (Agaricales, Fungi). Systematic biology, 61(4), 595-607.