North American species of Mycena.

224 NORTH AMERICAN SPECIES OF MYCENA

slightly acidulous, odor weakly or strongly nitrous if fresh material
is crushed, occasionally lacking or somewhat radishlike; lamellae
ascending-adnate and usually toothed, subdistant to distant (sometimes appearing close in young pilei), 12-18 reach the stipe, one to
three tiers of lamellulae, narrow to moderately broad, faces pale or
dark grayish vinaceous, edges colored pale pink or rose color at least
on the larger gills, the edges of the lamellulae sometimes concolorous
with the faces; stipe (2) 3-6 (8) cm. long, 1-1.5 (2.5) mm. thick, equal,
hollow, very fragile, with a faint bloom at first, soon naked and
polished, translucent, base sparsely white-strigose, color pale or dark
grayish vinaceous, apex sometimes pallid and base sordid.
Spores ellipsoid to slightly obovoid, 7-9 (10) X 4-5 A (10-13 [14]
X 4.5-6 j in two- and three-spored forms), amyloid; basidia two-,
three-, and four-spored; cheilocystidia and pleurocystidia similar in
size and shape but variable in distribution, usually abundant though
at times rather rare on either the sides or the edges or both, fusoidventricose with obtuse apices or elongating and subcylindric with
slightly tapered apices, smooth to rarely forked, contents pale or dark
pinkish brown; gill trama vinaceous brown in iodine; pileus trama
with a thin adnate surface pellicle, beneath it a broad region of vesiculose cells half the trama in thickness (the hypoderm), the remainder
filamentous, dark vinaceous brown beneath the pellicle in iodine,
contorted lactiferous hyphae present in both cap and gill trama.
Habit, habitat, and distribution.-Densely gregarious to scattered
on needles under conifers, summer and fall, often common. Occasionally on humus or moss in oak woods; Tennessee, New York, Michigan,
Idaho, Washington, Oregon, and California in the United States and
Ontario in Canada.
Material studied. -Smith, 33-1021, 691, 701, 713, 724, 834, 1270,
1345, 1418, 1616, 1649, 1741, 1742, 2509, 2532, 2548,2743,4041,4060,
4378, 5037, 7001, 7976, 8042, 8111, 8414, 8765, 8768, 8771, 8826,
13772, 13953, 14202, 14631, 18115. Atkinson, 18381. Kauffman,
September, 1915, Michigan; September 12, Idaho, 1922. Mains,
34-116, 34-191, 34-194. Morse, California. Stuntz, 589.
Observations.-The two color forms were collected in the same
plantation at the same time and appeared to be genetically distinct.
Both were two-spored. The dark-red form has been found only in
the one locality.
The color of the gill edges varies directly with the number of
cystidia present, and in forms with only scattered cheilocystidia the