North American species of Mycena.

64 NORTH AMERICAN SPECIES OF MYCENA

pressed or slightly incurved margin, becoming obtusely conic to campanulate, sometimes broadly convex to nearly plane, small individuals
sometimes papillate, surface lubricous to subviscid, glabrous or
appearing somewhat granulose near the margin owing to the slight
checking of the cuticle, translucent-striate on the margin when moist,
pellicle tenacious and completely separable, colors extremely variable,
when perfectly young and fresh a beautiful pale blue or greenish blue,
soon tinged with brown and assuming various degrees of bluish,
greenish, or grayish brown with a pallid margin, often sordid yellowish in age, bluish tints often lingering on the margin; flesh thin, pallid,
pliant, odor and taste mild, lamellae close to crowded, 18-25 reach
the stipe, two or three tiers of lamellulae, ascending-adnate, sometimes narrowly adnate or practically free, narrow to moderately
broad, white or tinged grayish, edges slightly fimbriate; stipe 3-8 cm.
long, 1-2 (2.5) mm. thick, equal, terete, flexuous or strict, tubular,
cartilaginous, elastic, at first densely pruinose or minutely pubescent
over all from a dense coating of caulocystidia, somewhat glabrescent,
base mycelioid, the mycelium blue at first but soon fading to white,
bluish to greenish blue above at first, soon fading to grayish or finally
sordid brownish.
Spores 6-8 X 6-7 (8) u, globose or subglobose, amyloid; basidia
four-spored; pleurocystidia not differentiated; cheilocystidia abundant, 32-60 X 5-8 pu, subfusoid with obtuse apices but becoming more
or less cylindric, sometimes flexuous, smooth, hyaline; gill trama
homogeneous, very faintly brownish in iodine; pileus trama characterized by a thick gelatinous pellicle (blue color located along the surface
of the pellicle in incompletely gelatinized hyphae), homogeneous beneath the pellicle and faintly vinaceous in iodine; stipe covered with
numerous cystidia similar to those on the gill edges or more elongated
and flexuous, the tissue of the stipe becoming deep vinaceous red in
iodine.
Habit, habitat, and distribution.-Single, scattered or gregarious
on debris, decaying wood, or on the bark around the bases of live
trees of oak in particular, but also occurring quite frequently on decaying wood of basswood, elm, beech, and other hardwoods. I have
seldom collected it in great quantity, but have found it regularly
every season near Ann Arbor. It fruits during both the spring and
fall, though it is more abundant locally in the spring. It is widely
distributed in eastern North America; I have examined material from
Alabama, North Carolina, Tennessee, Pennsylvania, New York,