California Fungi—Vascellum pratense
Fruiting body 3.0-6.0 cm tall, 2.0-5.0 cm broad; shape variable: turbinate, obovoid, cylindrical with a slightly enlarged apex, sometimes laterally compressed and appearing fan-shaped, typically tapered towards the base, the latter often with characteristic wrinkles and folds; apex rounded to truncate; exoperidium consisting of a dense covering of evanescent, whitish to cream-colored, short spines and granules, less conspicuously ornamented towards the base; endoperidium thin, smooth to slightly roughened, white becoming cream to ochraceous-brown, grey-brown to medium-brown in senescent specimens; spores dispersed via a gradually enlarging apical tear; sterile base prominent, a subgleba occupying up to half of the fruiting body, composed of relatively large, whitish cells becoming yellowish to yellowish-olive, finally brown to purple-brown; subgleba separated from the spore case by a thin membrane, i.e. a diaphragm; gleba white, soft, becoming yellowish-olive, in age olive-brown, powdery; odor and taste mild when young; capillitium sparse, located mostly near the endoperidium; paracapillitium common.
Spores 3-3.5 µm, round, with a minute pedicel, finely warted in KOH, appearing spinulose in cotton blue, moderately thick-walled, with a single oil droplet.
Solitary, gregarious to clustered in grassy areas; fruiting during the summer months in watered areas and after the fall rains.
Edible when white and immature, but of little value.
Vascellum pratense is one of several modest-sized puffballs found in lawns and playing fields. Its distinguishing characteristics include a prominent sterile base and spore case separated by a thin membrane (best seen by longitudinally sectioning the fruiting body), an exoperidium of pallid, evanescent spines and granules, and a thin endoperidium that changes from whitish to ochraceous, to brown. In old, dried specimens, the spore case may disintegrate leaving only a sterile cup-like base. Two other puffballs encountered in grass include Bovista plumbea and Bovista aestivalis. These can be told at a glance by a more or less round shape, relatively smooth surface, and lack of a sterile base. Vascellum lloydianum is a closely related species which differs in having an indistinct diaphram and more abundant capillitium. It is also commonly collected.