Summary:
Also listed in Puffballs category with other Scleroderma species. Features include 1) the size and ornamentation of the spores (an important differentiating character), 2) underground or somewhat underground growth, 3) shape spherical to somewhat pear-shaped, at times with irregular lobules, 4) color whitish to yellowish or yellowish brown, staining with injury iodine yellow or dark reddish, 5) surface smooth or lightly cracked at top, with poorly defined scales, 6) flesh up to 0.3cm when dried, staining reddish like surface, 7) dehiscence [opening] not observed much, opening by irregular tearing at top, also deliquescing, 8) spore mass white becoming olive-gray, blackish violet, or dark purple-chocolate, with inconspicuous whitish to yellowish threads, 9) somewhat downward projecting base with white rhizomorphs, 10) rubbery to farinaceous odor and taste, and 11) growth in coniferous woods, occasionally in sand, or under lawn sod. Guzman includes S. arenicola Zeller as a synonym but notes that S. arenicola Zeller sensu Smith 1951 is S. michiganense (Guzman) Guzman. It is common among false truffles in the Pacific Northwest.

Interior:
when young fleshy, alveolate and white, when mature powdery and olive-gray, blackish violet, or dark purple-chocolate; with filaments that are whitish or yellowish and not very conspicuous, (Guzman), violet with yellow threads (Ramsey), at first white, then yellowish, turning purplish umber when mature (drying black where cut), (Zeller)

Odor:
when fresh strongly rubbery, but when dried mild or sometimes disagreeable, (Guzman), farinaceous when young, but becoming strongly alkaline when deliquescing, (Zeller)

Taste:
when fresh strongly rubbery, but when dried mild or sometimes disagreeable, (Guzman), farinaceous when young (Zeller)

Microscopic:
spores (15)18-23(25.5) x (15)18-23(25.5) microns including spines, strongly spiny and reticulate, the spines curved or with T-shape, ornamentation 1.5-4 microns high, reddish brown in Melzer''s reagent, yellowish brown or dark brown in KOH; when immature the spores are smooth, oval, 8-16 microns in diameter and brown, (Guzman), spores 11-25 x 11-25 microns, average 14 microns, nearly round, alveolate-reticulate, dark purplish umber; basidia 10-13 x 8-10 microns, pyriform to subglobose, colorless, usually 4-spored, (Zeller), spores 17-20, with spines less than 1 microns long, (Sims)

Notes:
Scleroderma hypogaeum is found from southern WA to southern CA, (Trappe(13)). Collections were examined from BC, WA, OR, ID, CA, CO, MT, and Mexico, (Guzman).

Synonyms and Alternate Names:
Hypochnus violeus Quel.
Scleroderma arenicola Zeller