Cap 0.7–2.2 cm in diameter, convex to broadly umbonate, margin smooth to crenulate, tacky when moist, not hygrophanous, uniformly colored or indistinctly bicolored, at center clay-buff to dark olive buff, margin very thin, grayish pink or central color extending to margin, with no traces of veil. Lamellae initially pale, later sordid clay-brown, emarginate, maximum depth 2 mm, number of lamellae {L} 28–40, droplets often absent but occasionally visible even with the naked eye, white fimbriate edge present. Stem 0.8–2.5 × 0.2–0.3 {median} × 0.1–0.3 {base} cm, initially pale, later sordid brownish, cylindrical to clavate, occasionally tapering, stem Q (4–)4.6–7.6(–9.2), pruinose to slightly fibrillose. Context firm, interior stuffed, flesh discoloring weakly from base. Smell absent or raphanoid. Taste not recorded. Spore deposit grayish brown.

Spores amygdaloid, limoniform, weakly to strongly papillate, on ave. 12.0–13.0 × 7.0–7.5 µm, ave. Q = 1.6–1.8, yellow brown to brown, guttulate, almost smooth to weakly ornamented (O1O2), perispore not loosening (P0), indextrinoid to indistinctly dextrinoid (D0D1 (D2)). Basidia 24–56 × 6–12 µm, ave. Q = 3.2–4.6, mostly four-spored. Cheilocystidia clavate-stipitate, occasionally spathulate-stipitate or capitate-stipitate or clavate-lageniform, occasionally with characteristic apical wall thickening, occasionally bifurcate, septate or sinuate, on ave. 42–59 × 6–11 (apex) × 4.0–5.5 (middle) × 3.5–6.0 (base) µm, ratios A/M = 1.48–2.51, A/B = 1.99–2.92, B/M = 0.81–1.24. Epicutis an ixocutis, up to 100 µm thick (measured from exsiccata), maximum hyphae width 6 µm, sometimes encrusted, trama elements beneath subcutis cylindrical, sausage-shaped. Caulocystidia similar to cheilocystidia, up to 75 µm long.

W-Greenland: Kangerlussuaq, c. 2 km W of the Airport, 67.06°N, 50.68°W, 10 Aug 2000, A-M. Larsen, T. Borgen (TB00.061, C-F-103518), 50 m, with Salix glauca in ditch. Kangerlussuaq, Sandflugtsdalen, 67.06°N, 50.42°W, 25 Aug 2016, S.A. Elborne (SAE-2016.197-GR, C-F-106747), 110 m, with Salix glauca in dune slack. E-Greenland: Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 6 Aug 2017, H. Knudsen (HK17.128, C-F-105029), 40 m. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.76°N, 22.65°W, 6 Aug 2017, S.A. Elborne (SAE-2017.125A-GR, C-F-106763), 40 m, with Salix arctica at riverside. Jameson Land, Nerlerit Inaat/Constable Pynt, delta of Gåseelv valley, 70.77°N, 22.69°W, 6 Aug 2017, S.A. Elborne (SAE-2017.125B-GR, C-F-106763), 15 m, with Salix arctica at riverside.

Recently described from Svalbard (Beker et al. 2016). The five Greenland collections all occurred north of 67°N and thus provide evidence that H. louiseae is a species of the High Arctic zone. It has not yet been recorded in alpine regions. The Greenland collections are the first from North America and the first outside Europe.

Five collections, with Salix glauca and S. arctica in calcareous soil and seemingly moist localities. From Svalbard it was recorded with S. polaris (Beker et al. 2016).

Hebeloma louiseae is easily recognized among the arctic Hebeloma species by the small basidiomes, the relatively few lamellae and the large basidia, although not present in every collection.