Summary: Also listed in Cups category. Features include deep brown cups with a white to yellow-brown stem about half as tall as the cup, sharp ribs on the stem continuing at least a third of the way onto the cup and sometimes to the margin, fruiting in spring, and microscopic characters. It is possible that the Californian variation is a different species from the northern variation, and this is the reason for the group designation. ''acetabulum'' does not agree in its ending with ''Helvella'' because it is a noun rather than an adjective.
Odor: none in particular (Lincoff(1))
Taste: none in particular (Lincoff(1))
Microscopic: spores 16-20 x 11-13.7 microns, broadly elliptic, smooth, colorless, with 1 droplet; asci 260-330 x 16-18 microns, pleurorhynchous; paraphyses 4-6 microns wide at tip, clavate to nearly equal, enlarged gradually to tip, "pale brown, contents finely granular", (Abbott), spores 17.5-19(20.5) x 11.5-13.5 microns, broadly elliptic, smooth, colorless, with 1 droplet; asci 8-spored, 270-320 x 15-20 microns, not turning blue in iodine; paraphyses cylindric, septate and branched at base, tips with slight clavate thickenings to 6-8 microns, (Breitenbach), 16-20 x 11-14 microns, elliptic, smooth, with central oil droplet, (Arora)
Notes: Collections were examined from BC, WA, OR, ID, and also AB, MB, ON, WY, Great Britain, Netherlands, France, and Scandinavia, and it has been reported from Asia, (Abbott). It has also been recorded from AZ, CO, and UT, (Larsen), CA (Arora).
EDIBILITY
poisonous (Phillips), sometimes reported as edible with caution, (McKnight), fair when cooked, especially after being boiled, poisonous raw, (Lincoff(1))
Habitat and Range
SIMILAR SPECIES
Helvella costifera has been separated on the basis of color (H. costifera is grayer and the underside is not yellow brown), ribbing (H. costifera ribs are blunt and often more widely spaced, but rarely ribs on H. acetabulum are blunt), and fruiting time (H. costifera fruits later, but overlaps with later collections of H. acetabulum), (Abbott). Harmaja describes other similar species from Fennoscandia including two with small fruiting bodies and spores averaging larger that fruit from late July to August, (Harmaja(9)). See also SIMILAR section of Helvella leucomelaena.
Habitat
single to gregarious on soil or litter in coniferous, mixed or hardwood woods, March to July, (Abbott), single to gregarious in hardwood and coniferous forests, in pastures, commonly on pathsides and roadsides, on sandy chalky soil, April to June, (Breitenbach), single to gregarious on ground in woods and at their edges, spring and summer, but in California may fruit in winter and early spring, (Arora), May to June (December to April in southwest), (Phillips)