The North American species of Psathyrella.

62

MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Key to the Species of Section Pseudostropharia
1. Pileus white to pallid when young and moist. 2
1. Pileus honey-brown to darker at first. 3
2. On burned areas; spores 8-10.5 X 4.5-5.5 u. 26. P. gruberi.
2. On or around hardwood stumps; spores 6.5-7.5 X 3.2-3.8 g. see 23. P. insignis.
3. Spores 11-15 X 6-7.5 /L. 29. P. annulata.
3. Spores smaller. 4
4. Taste very disagreeable (See 32. P. kauffmanii also). 27. P. pseudocotonea.
4. Taste mild or slight. 5
5. Spores 9-12 X 4.5-6 u; odor aromatic. 28. P. caputmedusae.
5. Spores 7-10(-11) A long. 6
6. Growing on Sphagnum. 30. P. sphagnicola.
6. Not as above. 7
7. Pleurocystidia more or less utriform to fusoid-ventricose with broadly rounded
apex. 8
7. Pleurocystidia acute to obtuse or subcapitate (but then the neck narrow) more
rarely some with a rounded apex. 11
8. Annulus pallid, thin and membranous. 9
8. Annulus thick and cottony. 10
9. Spores 8-10 X 4.5-6 L. 31. P. solheimii var. solheimii.
9. Spores 7-9 X 4-5 f,. 32. P. kauffmanii.
10. Spores (many of them) somewhat truncate (in face view) at the base.
see 34. P. barrowsii and 400. P. battarae also.
10. Spores 8-10 X 4.5-6; annulus soon avellaneous to wood brown; spores not
truncate at the base. 31. P. solheimii var. sanjuanensis.
11. Pileus dark purple-drab to vinaceous-gray; walls of some pleurocystidia slightly
thickened but hyaline and highly refractive. 33. P. subpurpurea.
11. Not as above (walls of cystidia yellowish if thickened slightly). 12
12. Annulus thick and cottony, becoming gray-brown in drying; pleurocystidia
obtuse to subcapitate. 34. P. barrowsii.
12. Not as above. 13
13. Spores with a truncate apex; walls of some pleurocystidia yellowish in KOH
(especially if slightly thickened), acutely pointed. 35. P. ellenae.
13. Spores not truncate at apex (under a low-power oil immersion); pleurocystidia all
hyaline and obtuse to subacute. 36. P. longistriata.
26. Psathyrella gruberi A. H. Smith, sp. nov.
Pileus 3-6 cm latus, obtusus demum late campanulatus, albo-squamulosus,
ad marginem appendiculatus, pallidus demum ligno-brunneus; odor graveolens;
lamellae pallidae demum violaceo-fuscae, confertae, latae, adnatae; stipes 5-8
cm longus, 8-10 mm crassus, fibrillosus, deorsum squamulosus, sursum annulatus;
annulus albidus, gossypinus; sporae 8-10.5 x 4.5-5.5 g, apiculatae; pleurocystidia
40-60 x 10-15 (-20), ad apicerum obtusa vel late rotundata; caulocystidia 40-80
x 10-15 A, flexuoso-subeylindrica, anguste clavata vel fusoide ventricosa; fibulae
adsunt. Typus. Smith 28041 (MICH); legit prope Bear Springs, Mt. Hood
National Forest, Oregon.
Illust. PI. 15; Text Figs. 75-78.
Pileus 3-6 cm broad, obtuse with a slightly bent in margin when young, at
maturity broadly campanulate to umbonate, surface at first covered by a dense
coating of white superficial squamules, soon glabrescent from the disc out, near
"tilleul buff" (whitish) when young, darkening to near avellaneous or wood
brown or grayish cinnamon-buff on disc by maturity, margin long remaining
paler and at first coarsely appendiculate from the remains of the membranous
veil or veil breaking to leave a thick cottony apical annulus. Context pallid,
taste mild, odor very strongly sweetish-fragrant.