September 9th, 2010


50 More Urban Species #31 Giant Puffball; Urban Nature Pictures 9/7

Giant puffball Calvatia gigantea

Not everyone has encountered a giant puffball, but surely everyone who has remembers the experience. Often they are mistaken for deflated volleyballs, or soccer balls that have faded to all-white. A group of particularly large giant puffballs, dotting a meadow, might be taken to be a flock of sheep. Each mushroom ranges in size from that of a grapefruit up to a meter across. The fungus organism, hidden in the soil, is a larger creature made of millions of interlacing threads only a single cell wide. These threads exude digestive juices into the soil, breaking down chemicals into usable nutrients and reabsorbing the result.

All mushroom-producing fungi live this way, though many live in dead wood instead of soil, and others live within or among the roots of living trees. Secondary decomposers (or secondary saprobes in the terminology of mycologists) feed in places where other fungi and bacteria have already done some work breaking down formerly living things into smaller, more digestible parts. A microscopic puffball spore must drift to such a place, and somehow escape the predations of springtails, slime molds, earthworms and a myriad other creatures in order to grow into fungus organism, . The odds seem very bad for the spore, perhaps that's why each giant puffball produces more than a trillion spores. Surely one will reach the right spot.

Giant puffball links:

Tom Volk's page on the species:

David Fischer's page on the species and its relatives:

Michael Kuo's page on the species:

Two years ago they appeared three weeks earlier, for some reason. I ate one:

Goofballs with puffballs:

(Thanks to Tom Volk and David Fischer for responding to my questions about this species.)