Summary:
Features include 1) a tough top-shaped fruiting body with a knobby or lumpy cap surface that is whitish when young or on the actively growing margin but otherwise orange to rusty cinnamon, 2) flesh that is orange to rusty-cinnamon and corky except for a thin upper spongy layer on cap, 3) short, blunt, whitish teeth, 4) orange to rusty cinnamon stem, 5) mild to faintly fragrant odor, and 6) bitter to farinaceous taste. Hydnellum aurantiacum, (and probably also H. peckii), have been reported to associate with the myco-heterotrophic plant Hemitomes congestum (gnome plant), according to Trudell(2003). The H. aurantiacum complex includes also H. conigenum, H. complectipes, and H. auratile; however, Harrison(3) describes H. conigenum as common in the Pacific Northwest and Harrison(4) does not include the other two in the list of North American Hydnellum species known to them, whereas Hall includes only the second and third for WA. Because Harrison(3) points out the similarity between H. conigenum and H. auratile of Europe, the two names could be referring to the same taxon in the Pacific Northwest. Hall(3) describe two varieties besides the type variety, 1) var. bulbipodium with abruptly bulbous stem thickened by a spongy layer, with brownish orange or brownish red cap and tawny to orange margin, depressed to funnel-shaped with thin cap flesh, some with one or two proliferating caps, with tomentum agglutinating into prominent radiating ridges, and spines that are brown at the bases, and 2) var. colliculosum, with dingy brownish orange cap (brighter than var. bulbipodium but less bright than var. aurantiacum) and yellowish orange margin but without bulbous stem, radiating ridges if present not prominent, nodules not present on cap, and flesh not as thin as in var. bulbipodium, teeth also with brownish bases. Hall''s description below is for the type variety; for the other descriptions the variety is not specified.

Chemical Reactions:
surface black with KOH, flesh dingy olive with KOH, (McKnight)

Odor:
mild (Arora), in drying faint but distinct and fragrant, "not at all like fenugreek", and undiminished for years, (Coker), fragrant, persistent, (Phillips), pungent, disagreeable, (McKnight)

Taste:
bitter to farinaceous (Arora), mild or slightly unpleasant (Miller)

Microscopic:
spores 5.5-7.5 x 5-6 microns, nearly round, prominently warted, (Arora), spores 6.0-7.0 x 5.0-6.0 microns, nearly round to round, coarsely tuberculate, inamyloid; basidia 3-spored or 4-spored, 30-35 x 6-8 microns; hyphae branched, incrusted, without clamp connections, (Hall), spores 4-5 x 3.7-4.2 microns, nearly round or round, strongly tuberculate; basidia 4-spored, 6 microns wide; hymenium about 40-45 microns thick, (Coker), spores 5.5-6.5 x 4.5(5) microns, nearly round, with coarse blunt tubercles, light brown; basidia 4-spored, 30-35 x 5.5-8.5 microns, slenderly clavate, without basal clamp connection; cystidia not seen; hyphal system monomitic, hyphae 2-5 microns wide, colorless to light brown, thin-walled to thick-walled, septa without clamp connections, (Breitenbach)

Spore Deposit:
brown (Arora)

Notes:
H. aurantiacum is found in FL, NC, NY, and RI, and reported throughout the United States and Canada from NS to FL, (Coker). It is found at least in WA (Hall), CA (Arora), CO (Lincoff), under conifers in Europe and North America generally, (Harrison(3)), and also occurs in Asia (Trudell(4)). There are collections from BC deposited at the Pacific Forestry Centre including some determined by K.A. Harrison. There are collections from OR deposited at Oregon State University. The University of Washington also has collections from AK.

EDIBILITY

no (Arora)

Synonyms and Alternate Names:
Boletus castaneus Fr.