The North American species of Psathyrella.

212

MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Distribution. Michigan.
Observations. The concept of P. gossypina current in Europe is for a Psathyrella having a globular inclusion in the very large pleurocystidia. Hence my
previous assignment of the material described here to P. gossypina is best regarded
as an error even though the macroscopic features with the exception of the slightly
colored veil answer the Friesian description rather well.
Material examined. Michigan: Smith 1743 (Type), 72629.
169. Psathyrella variabilissima A. H. Smith, sp. nov.
Pileus 1-2.5 cm latus, conicus demum campanulatus vel late convexus, sparse
fibrillose-squamosus glabrescens, pallide ochraceus demum rugulosus; lamellae
confertae, subdistantes, latae, ochroleucae demum purpureo-brunneae; stipes
4-5.5 cm longus, (1.5)2-4 mm crassus, albidus demum lateolus, fibrillosus, glabrescens; sporae 8-10 x 4.5-5.5 /, (12-15 x 3.5-4.5 /); pleurocystidia (42-) 56-70
(-84) x 9-16 u, fusoide ventricosa, obtusa vel subcapitata; fibulae adsunt. Typus.
Smith 5 (MICH); legit prope Ann Arbor, Michigan.
Illust. Text Figs. 380, 381.
Pileus 1-2.5 cm broad, obtusely conic when young, expanding to campanulate
and finally nearly plane, surface at first covered by scattered fibrils from the
remains of the veil but soon glabrescent, margin fibrillose-appendiculate for a
short time, color evenly pale yellow ("warm buff") over all and radially rugulose
at least near the margin, finally becoming drab as spores mature. Context
moderately thick but brittle, odor and taste slightly fungoid (not distinctive).
Lamellae close to subdistant, slightly adnexed, moderately broad, concolorous
with pileus or finally purple-brown.
Stipe 4-5.5 cm long, (1.5-)2-4 mm thick, white or sordid yellowish, hollow,
fragile, equal, with scattered pale buff fibrillose patches from the veil, nearly
glabrous in age or merely somewhat appressed fibrillose.
Spores very variable in size, typical range 8-10 x 4.5-5.5,u, variations include
spores up to 22x 4 /, narrow fusoid spores 12-15 x 3.5-4.5 /A, and various other
assortments of shapes (Fig. 381), wall smooth, pore present as a hyaline spot but
apex not truncate, shape typically (in face view) elliptic to oblong, in profile
subelliptic to obscurely inequilateral, color in KOH bister, slowly darkening
toward "mummy brown," in Melzer's dull tawny-red, wall about 0.2 g thick.
Basidia 23-32x8-11,, 2-spored and 4-spored, clavate, hyaline in KOH.
Pleurocystidia very abundant, (42-) 56-70 (-84) x 9-16 a, fusoid-ventricose with
obtuse to subcapitate apex or the apex branched or merely obtusely and obscurely
mucronate, sometimes irregular in shape, the upper part with one or more constrictions and the walls flexuous toward the base, wall thin, smooth and hyaline,
cell content in KOH or in Melzer's not distinctive. Cheilocystidia similar to
pleurocystidia or shorter and more saccate. Caulocystidia not located in revived
material. Hyphae of the veil with ochraceous content as revived in KOH.
Gill trama of parallel hyphae pale cinnamon to ochraceous in KOH. Pileus
with a cuticle of staggered inflated-pedicellate cells so arranged as not to form
a palisade and to appear to be several cells deep, their walls smooth, thin and
nearly hyaline in KOH. Hyphae of the trama pale rusty cinnamon in KOH in
the subcuticular region and with incrustations on them. Clamp connections
present.
Type locality. Whitmore Lake, Michigan.