The Urban Pantheist

These boletes, infected with what is probably Hypomyces chrysospermus were growing at the base of one of the eastern white pines in my yard.

Hypomyces chrysospermus is a fungus that feeds on other fungi. It has a preference for bolete mushrooms--those with porous undersides rather than gills--first attacking the spore-bearing surface with a white mold. After the mold has consumed the mushroom, its tissue turns bright yellow, the color of its own spore-producing cells.

A related mold, H. lactifluorum attacks Russula and Lactarius mushrooms, turning them into the sought-after edible called "lobster mushrooms." Boletes parasitized by golden bolete mold are not considered edible.

This bicolored bolete (Boletus bicolor/campestris complex) was growing beneath our shagbark hickory tree in the front yard.

"Bolete" is a non-specific term for mushrooms that produce spores through a spongy surface rather than the more familiar "gills." At one time all such mushrooms were in the genus Boletus, but as knowledge increased, these were split into dozens of other genera. Now just a few species of boletes are boletus. One dangerous misconception about these mushrooms is that none are poisonous--or that simple rules can distinguish poisonous ones from edible ones. The truth is that identification to species is the only way to be sure any mushroom is poisonous, and several species of bolete can make a person quite ill.

Bicolored boletes are a complex of several species of yellow and red mushrooms with flesh that bruises blue when damaged. You can see in the photograph that when I pulled some grass around the mushroom (to get a clearer shot of the mushroom) my hand brushed against the spore bearing surface which quickly turned blue. Boletus bicolor is supposed to bruise slowly, while B. campestris bruises quickly--but campestris has very small pores, and this mushroom has relatively large pores. This specimen was also heavily water-logged, which could probably affect both field markings. It will have exist in ambiguous realm of a "species complex" for now.


Not far away, a pair of dusky slugs work at making more mushroom-munching mollusks.

I've seen this one pop up outside the zoo hospital offices for a couple years now. Pretty sure it's Amanita rubescens. No one is quite sure if this species (if that's what this is) is edible for humans or not. A squirrel took one bite of this and decided that was plenty.

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A good number of interesting mushrooms have appeared at Franklin Park Zoo this summer. This one caught a lot of people's attention. It was much lighter when it first emerged, and you can see it's starting to decay. This is Bondarzewia berkeleyi. Most notable for it's large size, it's a parasite of oak trees. This one is emerging from the ground, feeding on the hidden wood of a now gone tree.

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This is one of the Amanitas growing in mulch , from this photograph. I was confused, since Amanitas are all mycorrhizal, growing in symbiosis with tree roots. Most of the time you see mushrooms in mulch, they are produced by a fungus that is consuming the mulch. I consulted the experts, one of whom wanted to know if the mushroom had a volva (the remains of the veil that encapsulated the mushroom when it was young) on the base. I dug it out and took this picture. It has a volva, and also has rhizomorphs: threads of rootlike mycelium coming from the base. Amanita rubescens, or a close relative, was the consensus.

Photo by cottonmanifesto. Age has made the strange, concave appearance of this individual mushroom: as a mushroom gets older, the edges curl upward, so that the spores closest to the stalk have more room to be released. Location: Olmsted Park, Brookline.

Urban species #249: Boletus bicolor

Like Russula emetica (the sickener), Boletus bicolor is probably a complex of several related species that look very much alike. Unlike R. emetica, B bicolor will not make you throw up when you eat it. In fact, this mushroom is one that is sought after by many foragers. An over-enthusiastic wild mushroom eater might mistake B. satanas or another poisonous species for B. bicolor, so caution is advised. In any case, this mushroom can be enjoyed simply for its attractive appearance. The distinctive contrasting colors of this mushroom demand attention, and are the reason for its scientific name (which is sometimes translated into a "common" name, bicolored bolete). The fungus that produces this mushroom, like most bolete fungi, are mycorrhizzal (an explanation of this term is found at the entry for amethyst deceiver). These mushrooms are usually found growing near mature oak trees, the tree and the fungus sharing nutrients in the soil.


The red cap of the mushroom is visible, here, from above. When younger, this mushroom would have had the familiar umbrella shape. Pores on the underside of bolete mushrooms release the spores, enabling the fungus to reproduce.