Fruiting body 2.0-4.0 (5.0) cm tall, 2.0-3.0 cm broad, pear-shaped to turbinate, gradually to abruptly tapered below to a well developed pseudostipe, the latter attached to the substrate by thin, white rhizomorphs; exoperidium a mixture of dark-brown to blackish-brown, short spines, < 1 mm in height, typically grouped and united at the tips, plus minute warts, in age sloughing away from the apex; endoperidium before maturation visible between the spines, cream-yellow, to brassy-yellow, paper-thin; gleba white at first, becoming yellowish-olive, at maturity brown to olive-brown; subgleba alveolate, buff-brown to ochre-brown with lilac tints; odor and taste not determined.
Spores 4.0-5.0 (5.5) µ, globose to subglobose, asperulate (finely warted), moderately thick-walled, with a droplet and stub-like pedicel; spores dull olive-brown in deposit; capillitium Lycoperdon-type, slender, straight to undulate, with abundant round to elongate, variable-sized pores; paracapillitium present.
Solitary to scattered on soil or duff in hardwood and conifer woods; fruiting from late fall to mid-winter; occasional.
Unknown, presumably edible when immature with a whitish interior; untried locally.
Lycoperdon umbrinum is a blackish puffball often misidentified as Lycoperdon nigrescens (=L. foetidum). The confusion is probably the result of conflicting interpretations in older field guides. Here we have relied primarily on Pegler, Laessoe, and Spooner in British Puffballs, Earthstars, Stinkhorns to separate the two. As noted by the authors, Lycoperdon umbrinum is variable, the color of the exoperidium ranging from medium-brown, reddish-brown, to blackish brown. California specimens tend towards the latter, thus the confusion with the often similarly colored Lycoperdon nigrescens. The two species, however, can be distinguished with other characters. Lycoperdon umbrinum, a cosmopolitan species, has an exoperidium composed of very short spines,<1 mm long, while the spines of L. nigrescens are >1 mm long, and unlike the former, when shed, leave scars on the endoperidium, much like those of L. perlatum. Indeed, Lycoperdon nigrescens has the aspect of a dark-colored Lycoperdon perlatum and was once considered to be a variety of the latter. Based on collections in the herbarium of San Francisco State University, Lycoperdon umbrinum is the common black puffball found in the San Francisco Bay area, while L. nigrescens is rare, if present at all. Lycoperdon nigrescens appears to be northern in distribution, found primarily in Idaho, Oregon, and Washington, possibly far northern California. Lycoperdon umbrinum should be compared to Lycoperdon molle which is similar in size and shape, but typically has a greyish-brown to medium-brown exoperidium composed of spines of variable length, some grouped and mixed with furfuraceous granules. It is best distinguished microscopically by its coarsely warted spores and presence of sterigmatal remnants.