The North American species of Psathyrella.

1972]

PSATHYRELLA

421

reach the stipe), moderately broad, color pale avellaneous when young, slowly
becoming fuscous-brown, edges even.
Stipe 2-5 cm long, 1-1.5 mm thick, equal erect, strict and rigid, tubular, densely
white pubescent (under a lens) at first, soon glabrous or with scattered fibrillose
flecks, whitish above, base sordid brown, in age yellowish or sordid brown over
all except the apex, base tinged reddish at times, occasionally longitudinally striate
over the lower half.
Spores 8-10 x 5-6 1k, smooth, truncate from a hyaline apical pore, ellipsoid, dull
fuscous in water mounts when fresh, blackish when revived in KOH under the
microscope but fading.
Basidia 4-spored. Pleurocystidia absent. Cheilocystidia Conocybe-like, 18 -23 x 10-14 x 3-4 /, ventricose in midportion, with abrupt narrow neck terminating
in a capitellum. Cuticle of pileus a palisade of pyriform cells measuring 18-50 X
10-30 /, slender hyaline hyphae with thin walls project from between the cells of
this layer to cause the pubescent appearance of the young pileus.
Type locality. Milford, Michigan.
Habit and habitat. Gregarious on sawdust in a shaded area, September.
Distribution. United States: Michigan, Tennessee. Canada: Ontario.
Observations. The pigment in the spores is apparently somewhat unstable
since, in revived material, at present the spores are by no means as dark as when
the original description was written. In fact they now appear to be "off-color
Conocybe spores."
Material examined. UNTED STATES. Michigan: Smith 9587, 10920
(Type), 36255. Tennessee: Hesler 15918. CANADA. Ontario: Smith 26469.
EXCLUDED SPECIES
Since the present work is not intended as a monograph of the genus for the
area designated, only certain species which I have been able to study and which
are clearly not recognizable or which clearly belong to some other genus are
included here.
1. alachuana (Drosophila) Murrill, Lloydia 5: 155. 1942.
No spores were located in the portion of the type studied. Pleurocystidia were
absent, and the cheilocystidia were 28-30x9-16 u, clavate to saccate and pale
yellow to pale cinnamon in KOH. My examination of the type material causes
me to suspect the species as being represented by sterile to partly sterile (possibly)
specimens. The "innate-squamulose" pileus, non-appendiculate pileus margin and
lack of pleurocystidia are a combination of features which does not allow it to be
placed in any of the infrageneric taxa recognized here.
2. amarus (Psathyrella) Ward & McDonald, Mycologia 57: 757-760. 1965.
When a description of this species (as a Psathyrella) was submitted to me, I
was forced to admit it was a species not in my key or ms. Later, on seeing the
type, I recognized it at once as belonging in the A. pediades group of Agrocybe!
Dr. Roy Watling of the Royal Botanic Garden of Edinburgh, Scotland, is engaged
in preparing a world monograph of Agrocybe and related genera.