Summary:
Features include 1) a somewhat spherical fruitbody with the base indented, 2) a surface that is white to olivaceous or brown but soon stained blue where bruised, 3) a spore mass that is white staining blue and becoming dark brown from spores, 4) an unbranched columella that extends through the spore mass, 5) underground growth under conifers, and 6) brown spores with even to irregular longitudinal ridges on 4-spored basidia. Kuo(12) provided evidence for the inclusion of Chamonixia caespitosa in Leccinum. Leccinum caespitosum was listed as a synonym of Chamonixia caespitosa in the online Species Fungorum accessed June 26, 2020. It is infrequent among false truffles in the Pacific Northwest (Trappe(13)).

Interior:
"with labyrinthine locules, nongelatinized", when young "white and staining blue when exposed, especially near peridium", when mature "dark brown from spores massed on the locule surfaces", (Castellano), "chambers small, oblong, not filled with spores at maturity", visible next to stem as peridium is absent or little developed around stem; "white at first, then dark army brown to vinaceous buff", (Smith), chambers irregularly oblong; spore mass white when young, brown-black when mature, (Breitenbach)

Odor:
pleasant, slightly resinous, (Castellano), not distinctive (Smith)

Taste:
not distinctive (Castellano, Smith)

Microscopic:
spores 13-22 x 10-16 microns excluding ornamentation, broadly elliptic, "6-14 straight to spiraling, often forked, dark brown, longitudinal ridges 3-5 microns tall, the lateral margins of the ridges ragged, the ridges not meeting at the spore apex", sterigmal attachment +/- 1 x 2 microns; basidia 4-spored, 32-38 x 15-20 microns; cystidia absent; trama of colorless, subparallel hyphae 3-5 microns wide, "the walls thin or slightly gelatinous thickened"; peridial subcutis of several tiers of more or less isodiametric, colorless, thin-walled cells up to 30 microns in diameter, often in radially aligned rows; peridial epicutis of loosely interwoven to appressed, colorless, thin-walled hyphae 7-9 microns wide; clamp connections absent, (Castellano), spores 18-20.5 x 12.7-15.2 microns, oblate, rich brown when mature, epispore long remaining colorless, finally brown, "irregularly wrinkled to form 8-10 longitudinal ribs", apex "slightly papillate but this often obscured by the wrinkles of the epispore", sterigmal appendage short, narrow, and colorless; basidia 4-spored, mostly about 36 x 18 microns, "in a true hymenium"; subhymenium "somewhat indefinite in thickness, of isodiametric cells"; hyphae of tramal plates 4-5 microns wide, colorless, only slightly gelatinous; "hypodermial zone of almost isodiametric cells somewhat radially arranged"; epicutis of peridium of appressed yellowish hyphae 7-9 microns wide; clamp connections absent, (Smith), spores 18-22 x 13-15 microns, oval, with longitudinal ribs, apex tuberculate, base with distinct apiculus; basidia 2-4-spored, 40-50 x 15-20 microns, clavate, (Breitenbach)

Notes:
It has been found in WA, OR, CA, NY, France, and Germany, (Castellano). It has been found from southwestern BC to northern CA, CO, (Trappe(13)). There is a Paul Kroeger collection from BC deposited at University of British Columbia.

Synonyms and Alternate Names:
Oligoporus tephroleucus (Fr.) Gilb. & Ryvarden
Polyporus tephroleucus Fr.