The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Subsection Obtusatae
Key to the Species of Subsection Obtusatae
1. Pleurocystidia measuring up to 60 A long or more. 2
1. Pleurocystidia seldom over 50 u long. 8
2. Spores 6.5-9 X 4-4.5. 3
2. Spores 8-10 X 4.5-6 ). 6
3. Pleurocystidia up to 85 )u long; some cheilocystidia with dull cinnamon content
in KOH. 356. P. directa.
3. Not as above. 4
4. Pileus milk-white before maturing. 357. P. angusticystis.
4. Not as above. 5
5. Veil of grayish fibrils; gills at maturity grayish brown. 358. P. subsimilissima.
5. Veil whitish; gills dark reddish brown at maturity. 359. P. obtusata.
6. Gills cinereous becoming black. 360. P. betulina.
6. Gills more or less cocoa-color at maturity. 7
7. Brachybasidioles present; stipe white and unchanging. 361. P. subargillacea.
7. Brachybasidioles absent; stipe soon brownish below. 362. P. fulvescens and variants.
8. Spores 6-7.5 X 3-4.5 u. 9
8. Spores larger. 10
9. Odor of camphor when fresh; veil grayish. 363. P. camphorata.
9. Odor mild; veil white. 364. P. albocinnamomea.
10. Pleurocystidia yellow in KOH and some up to 20 I wide. 366. P. subsquamulosa.
10. Not as above. 11
11. Spores up to 6 A/ wide; many caulocystidia ellipsoid to subglobose and with yellow
slightly thickened walls. 365. P. griseifolia.
11. Not as above (see P. velatipes also). 12
12. Lower portion of stipe soon discoloring. 13
12. Stipe not discoloring as in above choice. 14
13. Lamellae very narrow. 367. P. umbrosa.
13. Lamellae moderately broad (see 352. P. heterocystis and 362. P. fulvescens
also). 368. P. communis.
14. Pileus when young white to whitish. 369. P. lactobrunnescens.
14. Pileus some shade of brown when young. 15
15. Spore apex distinctly truncate. 370. P. wilsonensis.
15. Spore apex not truncate. 371. P. subterrestris.
356. Psathyrella directa A. H. Smith, sp. nov.
Pileus 1-3 cm latus, late conicus vel convexus, sparse fibrillosus, cinnamomeobrunneus dein subochraceus; lamellae subdistantes, latae, brunneolae demum cinnamomeae dein fusco-brunneae (in exsiccatis vinaceo-brunneae); stipes 3-5 cm
longus, 2-3.5 mm crassus, deorsum brunneus, sursum albidus, fibrillosus, glabrescens; velum fibrillosum; sporae 7-9.5 x 4-5 I,; pleurocystidia 50-80 x 10-16 u,
fusoide ventricosa, elongata, obtusa vel subacuta; fibulae adsunt. Typus. Smith
23789 (MICH); legit prope Still Creek, Mt. Hood National Forest, Oregon.
Pileus 1-3 cm broad, obtusely conic becoming broadly conic to convex, surface
moist and hygrophanous beneath a thin coating of white outer veil fibrils which
aggregate into fascicles and finally disappear, when moist cinnamon-brown, fading
to warm buff (yellowish) but when dried dull cinnamon (near "Sayal brown").
Lamellae subdistant, broad, adnate, brownish becoming dull cinnamon before
shaded chocolate-color by spores, near "Natal brown" as dried in oldest cap
(cocoa-color in younger ones), edges pallid-crenulate.
Stipe 3-5 cm long, 2-3.5 mm thick, equal fragile, hollow, white above, brownish
beneath the veil remnants toward the base, coarsely fibrillose at first from remains
of the white veil.
Spores 7-9.5x4-5,/, smooth, apex obscurely truncate from a distinct pore,
shape in face view oblong to elliptic, in profile subelliptic to obscurely bean