Summary:
Principal fieldmarks are small size, a depressed, somewhat hygrophanous light brown to yellowish tan cap, decurrent gills, a thin stem, and an association with the green granules at and near its base. The squamules are the vegetative stage, the mushroom is the reproductive stage, and the joint organism forms a basidio-lichen which Bigelow called Botrydina vulgaris, later considered a synonym of L. umbellifera. The associated alga is said to be in the genus Coccomyxa. L. umbellifera is probably the most common arctic agaric and is also common further south.

Cap:
0.5-2.5(3.5)cm across, at first flat with an incurved margin, becoming deeply depressed or funnel-shaped when old, margin often wavy; "dull cinnamon to brownish, fading to yellowish or straw color or paler as it ages"; smooth, not viscid, margin striate, (Arora), 0.5-1.5(3.5)cm across, flat at first with margin decurved [downcurved], disc soon shallowly depressed, when old sometimes broadly funnel-shaped; somewhat hygrophanous, brown when young becoming paler and more yellowish when old and with loss of moisture, finally pale yellowish to whitish, disc often remaining dark for some time; moist but not viscid, bald, margin striate when moist and often somewhat crenate [scalloped], plicate [pleated] at times, opaque when old and fading, (Bigelow)

Flesh:
very thin, pliant, (Arora), very thin, pliant; colored as cap, (Bigelow)

Gills:
decurrent, well-spaced; pale yellowish; sometimes veined, (Arora), "moderately decurrent to long decurrent (evenly), subdistant or distant, narrow to moderately broad", 0.1-0.3cm broad, thin, arched, at times forking, sometimes interveined; pale yellowish to pale creamy; edges even, (Bigelow), decurrent, widely spaced, pale yellowish, (Phillips)

Stem:
1-3cm x 0.1-0.3cm, equal or widened at base, pliant, often curved; pale reddish brown in upper part, yellow-brown to pale brown in lower part, often pale yellowish when old; smooth, (Arora), 1-2.5(3)cm x 0.1-0.2(0.3)cm at top, equal or either end slightly enlarged, round in cross-section, often curved, solid or hollow, cartilaginous-appearing but pliant; vinaceous brown at top when young, paler below, top remaining with vinaceous brown tint for some time but fading to pale yellowish in lower part; bald or nearly so in upper part, base with slight white tomentum, sometimes pubescent in upper part if embedded in wet moss, (Bigelow)

Odor:
not distinctive (Bigelow)

Taste:
not distinctive (Bigelow)

Microscopic spores:
spores 7-9 x 4-6 microns, elliptic, smooth, inamyloid, (Arora), spores 7-9(10) x 4-6(7) microns and up to 12 x 8 microns from 1-spored basidia, elliptic, smooth, inamyloid; basidia often 2-spored but also 1-, 3-, or 4-spored, 23-40 x 5-8.5(10) microns, sterigmata long, proliferated at times; cystidia not differentiated; clamp connections absent, (Bigelow)

Spore deposit:
white (Bigelow), white to yellow (Arora)

Notes:
It has been found in BC, WA, OR, ID, NS, NL, NU, ON, QC, YT, AK, CA, MI, MT, and NY, (Redhead(6)), MB, NC, NH, and VT, (Bigelow), and Europe, Asia, Africa, and Australia.

EDIBILITY

of no value (Arora)

Synonyms and Alternate Names:
Gerronema ericetorum (Pers.: Fr.) Singer
Omphalina ericetorum (Fr.) M. Lange
Phytoconis ericetorum (Pers.: Fr.) Redhead & Kuyper