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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Big puffball mushrooms are pure white when young. © Don Blegen
Big puffball mushrooms are pure white when young.

© Don Blegen

October 2007

Smoke from a bald giant

This massive fungi is a creamy puffball but not a pushover.

Anita Carpenter

A co-worker unceremoniously placed the medium-sized cardboard box before me.

"Have you ever seen anything like this?"

I carefully opened the box to find the largest mushroom I had ever seen. It was the size of a volleyball, pearly white and positively dwarfed the walnut-sized puffballs that were more familiar to me. All I could exclaim was "Wow! This is cool!" Then my naturalist's curiosity took over.

I just had to measure this giant. The puffball was a somewhat flattened oval, not a perfect sphere. It measured seven inches high, 22 inches around from top to bottom with a circumference at the widest point of 32 inches. The specimen weighed in at a hefty two pounds eleven ounces. With no evidence of spines or small hairs, the surface was as soft and smooth to the touch as kid gloves. On the bottom, the behemoth had a cord-like root where it must have attached to the mycelium.

Taxonomically, puffballs belong to the fungi order Gasteromycetes and the family Lycoperdales. Gastero means stomach, alluding to its defining feature, and all members of this order produce their spores completely within a fruiting body. More typical gilled mushrooms produce their spores exposed to the air so they can drop when mature. Several puffball species populate Wisconsin ranging in size from the tinier walnut-sized individuals to this huge one appropriately called Calvatia gigantea, the bald giant.

The puffball part is the fruiting body or the visible portion of a fungal colony. For most of the year, the fungus remains undetected, thriving underground and taking nourishment from decaying matter. For a few days each year, the fungus sends up this fruiting body, which is the spore-producing stage of its life cycle. Some mushrooms only grow on specific substrates, but puffballs seem to be generalists that grow on decomposing vegetation in the soil. They appear from late summer into autumn in a variety of habitats including meadows, woods and lawns.

This mushroom emerges as a tiny button and quickly expands to its impressive size. The smooth outer covering, called the peridium, protects the fertile, spore-producing tissue (gleba) inside. During this early growth stage when it is snow-white inside and out with no stalk, it's considered a choice edible mushroom, but check the identification with an experienced mushroom picker before you decide if its in a prime eating stage.

Once the puffball starts to mature, the gleba turns a yellowish-brown and is no longer edible. In fact the gleba tissue disintegrates into a fine powder and the ripe puffball has millions of spores ready to release. Even slight pressure can send them sailing on the wind. Gentle pressure from raindrops, hooves or a gentle pinch from a passing animal can force the spores through an opening in the top called an ostiole. Escaping spores look like smoke billowing from a chimney. On other puffball species the rubbery outer skin dries out, flakes away and the spores start floating away on even gentle breezes. The giant "puffs" out a fine yellowish-brown powder that drifts away on fickle winds. Millions of the spores are released in the hope that a few will settle on suitable substrate and find adequate nutrition and moisture to grow.

My giant puffball never made it to the mature stage intact. A few days later I dissected it to discover a spongy brownish gleba with a really earthy mushroom odor. The spores had not completely matured, so I put the marvelous specimen outside next to a pile of sticks. When I checked a week later, the smooth covering had turned gray and dried to a papery texture. Spores wafted away in mustardy clouds. I wondered if I will have a yard full of these giant puffballs next year. We'll just have to wait and see.

Oh how I wished I had discovered a puffball for myself on one of my outings. In all my years of exploration, I've never found one or been at the right lace at the right time. I keep hoping that if the bald giant sprouts on the landscape, I can take a closer look and my prize will earn a well-deserved WOW! from others who discover it too.

Anita Carpenter searches out the tiny and gigantic, the long and the short of it on walks near her Oshkosh home.