E-Flora BC: Electronic Atlas of the Flora of British Columbia

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.

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.

Cap:
3-15cm, columnar or somewhat top-shaped becoming flat or depressed when old, often with pine needles and other debris incorporated; "white when young or on actively growing margin, otherwise orange to rusty-orange to rusty-cinnamon", and eventually darker (brown) when old; velvety and suede-like when fresh, "often roughened by projecting knobs and lumps when mature, or in some forms with radiating ridges", (Arora), fruitbodies 7-8cm tall, cap 4-6.5cm wide, convex to top-shaped, margin thick wedge-shaped or rounded; two-colored, "Persian orange" to pale orange on disc, becoming "orange-white" to pale orange on the margin bruising to brown (colors in quotation marks from Kornerup(2)), (in the key Hall(3) give margin as whitish for this variety); nodular or reticulately scrobiculate, with suede-like tomentum, (Hall), fruitbodies "mostly very irregular, with protuberances, cavities, channels, and proliferations, often confluent", caps 3-7cm, thick; growing margin about salmon-buff, deepening toward center through rich orange-salmon to deep rust; finely tomentose on unweathered parts, (Coker), margin whitish to tan, or more often strong reddish orange, (McKnight), 2-7cm across, 0.3-0.8cm thick, irregularly rounded, top-shaped to funnel-shaped with undulating-crenate [wavy-scalloped] margin; when young whitish, later with weak concentric zones, orange-brown toward center, lighter to whitish toward the marginal zone; when young tomentose, smooth, later radially wrinkled-ribbed and with scattered tubercles, (Breitenbach), colors range from dull brown to brilliant orange, the texture and spongy layer on the surface grades from soft and thick to firm and thin, (Harrison(3))

Flesh:
"thick, tough and corky except for frequent presence of a spongier outer or upper layer"; orange to rusty-cinnamon to orange-red in both cap and stem, (Arora), fibrous woody, "reddish orange" in the disc, becoming "pale orange" to light orange toward the cap margin (colors in quotation marks from Kornerup(2)), in stem "may be duplex, if so then with only a thin outer layer", (Hall), in cap duplex, the upper layer about 0.03-0.1cm thick, soft and corky (and very friable when dry), colored like cap surface, when exposed to rain collapsing and becoming denser and inconspicuous, the lower layer thicker, tough and firm, red or reddish brown, horizontally zoned, often with layers of paler or darker color; in stem "consisting of a red, corky, usually rather thin outer layer and a hard, paler red or brownish core which is distinctly zoned", (Coker), in cap white to pale orange, sometimes zoned with dark lines, increasingly intense orange to orange-brown toward the stem, stem flesh duplex, (Breitenbach), when cut in half, the flesh is deepest orange in the lower part of the stem, even when old - usually the flesh of the cap is paler, sometimes almost white, (Trudell(4))

Teeth:
0.1-0.4cm long, short, blunt; "whitish to grayish or orange", becoming brown when old and with tips often paler, (Arora), up to 0.2cm long (up to 0.4cm long in var. colliculosum and var. bulbipodium and especially long in the latter), 2-3 per square mm, fleshy, round in cross-section, tapered, not subulate [not awl-shaped], not decurrent, or irregularly so; whitish, (Hall), 0.15-0.25cm long, small and slender; "grayish tan near the margin, deepening to a rich reddish brown and in age to a deep brown", (Coker), up to 0.5cm long, decurrent onto stem, whitish when young, later brownish to orange-brown, (Breitenbach), 0.5-0.7cm long, decurrent, close; dark brown with grayish buff tips, (Harrison(3))

Stem:
2-6cm x 1-3cm, usually central, tough or woody, equal or narrowing downward or in one form widened at base; orange to bright rusty-cinnamon becoming dark brown when old, with large mat of needles and debris usually stuck to base, (Arora), 4-5cm x 2cm, central, narrowing toward the base and pointed, "dark brown" (Kornerup(2)), duff sticking to exterior parts, (Hall), short, about 0.7-1.3cm wide, subequal [more or less equal], usually widening somewhat in lower part, very firm; undergoing the same changes of color as the cap, (Coker), 2-5cm x 0.5-2cm, gradually merging with cap, swollen toward base; orange-brown to dark brown; finely tomentose, (Breitenbach)

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)