Vascellum pratense

California Fungi—Vascellum pratense

Sporocarp
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
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.

Habitat
Solitary, gregarious to clustered in grassy areas; fruiting during the summer months in watered areas and after the fall rains.

Edibility
Edible when white and immature, but of little value.

Comments
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.