Summary:
Features include 1) a spherical to irregular fruitbody with a surface that has wood brown fibrils over a whitish ground color, and changes to bright pink where injured, 2) a spore mass that is white when young, becoming olive, 3) growth in very rotten wood, 4) an olive reaction of the peridial surface to KOH and FeSO4, and 5) microscopic characters including narrowly elliptic spores from 4-6-spored basidia, rare to scattered cystidia, and peridial epicutis with versiform cells 2-11 microns wide, many seta-like cells (flagellate hyphal ends). Molecular evidence has been presented to support the contention that Rhizopogon hawkerae (or at least a paratype and other collections identified as this species) is a synonym (along with R. parksii and paratypes of R. colossus var. colossus) of R. villosulus A.H. Sm. (Martin, M.P.(2)); on the other hand, other molecular evidence suggests that R. villosulus (different collection), R. colossus (holotype), R. hawkerae (same paratype), and R. villescens (non-type) are close and could be a single species that shows variation, whereas two non-type collections of R. parksii were more distant, (Grubisha(2)). Rhizopogon hawkerae is abundant among false truffles in the Pacific Northwest (Trappe(13)).

Chemical Reactions:
FeSO4 on peridium dark olive, KOH quickly pale olive, (Smith(30))

Interior:
"pallid becoming olive-buff" and finally nearly fuscous when old; "chambers empty, small and irregular", (Smith(30)), white when young, darkening to olive, (Trappe, M.(3))

Odor:
mild or slightly spicy (Trappe, M.(3))

Taste:
mild (Trappe, M.(3))

Microscopic:
spores 6.5-8 x 2.2-2.8 microns, cystidia 26-30 x 8-10 microns, "projecting 10-15 microns beyond the basidia"; "epicutis of hyphae with versiform cells 2-11 microns wide", "many setalike cells present, flagellate hyphal ends also present", (Smith(4)), spores 6.5-8 x 2.2-2.8 microns, narrowly elliptic to suboblong, in Melzer''s reagent weakly yellow, in KOH colorless singly and in masses along hymenium, no basal truncation seen; basidia 4-6-spored, 20-23 x 4-5 microns, "clavate, thin-walled, readily collapsing"; paraphyses "resembling basidioles, none seen with thickened walls, in KOH many with minute highly refractive globules"; cystidia rare to scattered, 26-30 x 8-10 microns, projecting 10-15 microns beyond hymenium, fusoid-ventricose, colorless, thin-walled; tramal plates of somewhat interwoven, narrow, refractive, colorless hyphae (revived in KOH), nongelatinous in water mounts when fresh; peridial subcutis of colorless appressed-interwoven hyphae, bluish in places in KOH (fresh) and with amyloid granules as revived in Melzer''s reagent, 2-11 microns wide, no pockets of enlarged cells present, "as revived in KOH dingy vinaceous and with darker brown pigment pockets abundant"; peridial epicutis of hyphae with dark brown walls in KOH and water, "and the walls thickened (1-2 microns), smooth to rarely incrusted, the cells versiform, 2-11 microns diam", "many seta-like elements present in or projecting from the layer and tapered to a whiplike flexuous nearly hyaline apex about 1 micron in diam; the bases 3-6 microns in diam (the so-called flagellate hyphal ends)"; clamp connections absent, (Smith(30)), peridial subcutis has a characteristic red layer revived in KOH (use 25X objective), although this fades after about 5 years of dried storage to pale pink and may disappear entirely after 7-10 years, (NATS)

Notes:
It is found from southern BC to northern CA and ID, (Trappe(13)). It has been reported to the North American Truffling Society for OR and for Sproat Lake in BC. It was reported from OR by J. Smith et al. A specimen from WA was used in study (Grubisha(2)).

Synonyms and Alternate Names:
Clavaria pseudoflava Britzelm.
Clavaria rugosa Fr.