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Excerpts from Jim Conrad's
Naturalist Newsletter
from the September 6, 2009 Newsletter, issued from the Siskiyou Mountains west of Grants Pass, Oregon:
EARTHBALLS
For about a month as I've been watering Anita's flower garden each morning I've been watching some fungi develop. They look like medium-size brown potatoes lying on the moist ground below a pot's overflow tap, as you can see above.
I'd assumed that they were puffballs -- that on their tops eventually holes would develop where spores would escape, but instead the things began developing cracks with no signs of holes. To figure things out I had to pick one, and the moment I had one in my hand I knew that it was no puffball: It was too hard and too heavy for that. I cut one open and saw what you can see below:
Not a puffball, this, but something close to it, something sometimes called an earthball, a fungus of the genus SCLERODERMA. Species are separated in Scleroderma mainly on the basis of spore shape, which I can't see, but my specimens' form, habitat and external appearance suggest that they may be Scleroderma areolatum, or close to it. Scleroderma areolatum appears to be the most commonly collected earthball species found in Oregon.
The first time you recognize an earthball you think you've discovered something extraordinary, but once you have an eye for what they look like suddenly they show up all over the place; you've just been overlooking them. Even in the most ecologically ravaged urban apartment zone sometimes earthballs show up in abundance emerging from woodchip mulch strewn around ornamental shrubs and trees planted it and around parking lots.
The dark purple mass in the earthball's center eventually matures into a mass of dry spores, similar to what happens with the puffballs. However, no exit pore for the spores ever develops. The fungus's leathery cover simply gets progressively thinner and more brittle as the dark purple, firm, heavy spore mass -- the gleba -- dries into a powdery mass of dusty black spores. This week while thinning the strawberry beds I found several old ones that practically shattered when I poked them, releasing clouds of spores.
How would their spores ever have escaped if I hadn't come along? One earthball had completely collapsed into a messy black pile and I'd never have noticed it if I hadn't been watering the garden, and puff's of spores erupted from the pile each time a drop of water hit. Maybe this fungus's strategy is simply to wait for some random event to shatter it, releasing its spores, depending on some feature of chaos the human mind finds it hard to grasp.
Members of the genus Scleroderma are "ectomycorrhizal fungi," which means that their threadlike mycelium forms a sheath around a host plant's root tip, with both the fungus and the host benefiting from the resulting symbiotic relationship. Mycelia are the white fungal strands you see growing through humusy soil like roots, decomposing organic matter as they go.
The ectomycorrhizal relationship is regarded as one of the most ecologically and economically important of all of Earth's natural relationships. Therefore, these humble-looking little earthballs are to be respected for the services they render us all.
Most sources regard earthballs as poisonous or at last undesirable for eating.