Summary:
Features include growth on old fabric or on wood, small size, a kidney-shaped, dry, brown cap, light purple brown to pinkish cinnamon gills that are white-edged and stain dark brown with handling, an off-center, curved stem that is brown, furry, and narrows toward base, and a purple brown to dark brown spore deposit. The description derived from Redhead(18) except where noted.

Gills:
"adnexed to adnate and sometimes with short, decurrent teeth", close to subdistant, 3 or more tiers of subgills, gills narrow becoming moderately broad; "cinnamon" to "pinkish cinnamon" becoming ''light brown'' to ''moderate brown'' or ''grayish brown'', staining ''dark brown'' on handling, edges whitish; edges entire

Stem:
0.5-1.5cm x 0.1-0.5cm, eccentric [off-center] but not lateral, usually distinctly curved and tapered toward base; near "mikado brown" to "sayal brown" or ''dark brown'' to ''brownish black''; "often with a ''light brown'' to whitish pruinose to tomentose vestiture"

Odor:
faintly aromatic or not distinctive

Taste:
not distinctive

Microscopic spores:
spores 6-7(7.5) x 3.5-4.5 x 4.5-5 microns, 8.5 x 6 microns on ?2-spored basidia, oval and only slightly compressed, smooth, relatively thin-walled (<0.5 micron), with apical germ pore; basidia (?2)4-spored, 17-22 x 5.5-6.5 microns, "somewhat urniform, clamped, often appearing to be subtended by a small basal cell", colorless; cheilocystidia forming a sterile margin, 15-26 x 4.5-5.5 microns, "lageniform to fusoid-ventricose with a slightly undulate neck and obtuse narrow apex, often with a prominently swollen base", often capped by a colorless resinous drop, (Redhead(18)), spores 6.4-7.2(8) x 4-5 microns, in side view elliptic to subamygdaliform [somewhat almond-shaped], with an apical germ pore, in mass brown-vinaceous, wall up to 1.0 micron thick, smooth; basidia 4-spored, 17-24 x 5-7 microns, cylindric to clavate, often constricted subapically, thin-walled, colorless; pleurocystidia numerous to scattered, 17-30(35) x 4-5 microns, "always embedded but with an emergent neck", easy to overlook, "similar in shape to cheilocystidia, often with an apical droplet", cheilocystidia numerous, 15-30(33) x 4-5 microns, "clavate, lageniform to ventricose-rostrate", neck often wavy, apex narrowing and thin-walled, often with a membrane-bound hydrophobic golden droplet up to 7 microns diameter, (Sime), clamp connections present (Watling)

Spore deposit:
purple brown to dark brown (Redhead(18)), mid-brown (Buczacki)

Notes:
Deconica horizontalis was examined from BC, WA, OR, and CA, (Redhead). It was examined also from United Kingdom, France, South Africa, (Sime).

EDIBILITY

Synonyms and Alternate Names:
Melanotus horizontalis (Bull.) P.D. Orton