The North American species of Psathyrella.

19721

PSATHYRELLA

149

6. Pleurocystidia nine-pin-shaped, clavate-mucronate, or with an acute to blunt
apical extension, rarely obtusely fusoid-ventricose. 7
6. Pleurocystidia not as above. 11
7. Stipe base yellowish; on wood of conifers.
(see 413. P. turnagainensis also) 108. P. bigelowii.
7. Not as above. 8
8. Terrestrial; gregarious under aspen; pleurocystidia ventricose-rostrate.
109. P. utahensis.
8. Lignicolous; pleurocystidia nine-pin-shaped to mucronate, rarely with subapical projections or obtusely fusoid-ventricose. 9
9. Pileus "cinnamon"; spores 7-9(-10) X 4.5-6 /u. 110. P. madeodisca.
9. Pileus dark cinnamon-brown to russet at first; spores 6.5-8 X 3.5-5.5 u; on logs,
stumps etc. later in the season than the above. 10
10. Spores 3.5-4.5 u wide, terete; pleurocystidia subfusoid with a narrow extended acute apical projection. 111. P. canadensis.
10. Spores 4.5-5.5 u in broadest view; pleurocystidia more or less mucronate but
mucro often enlarged slightly at apex. 112. P. delineata.
11. Habitat lignicolous (often on chip-dirt). 12
11. Habitat typically terrestrial. 21
12. On wood of conifers. 13
12. On wood of hardwoods. 16
13. Spores compressed slightly; lamellae drab-gray when mature. 113. P. oregonensis.
13. Spores terete; gills rusty brown or chocolate-color when mature. 14
14. Spores with a distinct apical pore and spore apex truncate; pleurocystidia
38-50 / long. 114. P. rugulosa.
14. Spore apex not distinctly truncate; pleurocystidia up to 70,u long. 15
15. Some pleurocystidia with slightly thickened yellow walls as revived in KOH; a thin
outer veil showing on young pilei. 115. P. pseudoparadoxa.
15. Pleurocystidia with thin walls; outer veil absent. 116. P. wapinitaensis.
16. An appreciable number of pleurocystidia with slightly thickened highly
refractive walls. 17
16. Pleurocystidia thin-walled throughout. 18
17. Spores 6.5-7.5, long; on alder logs. 117. P. indecorosa.
17. Spores 7.5-9 / long; on canes of Rubus and adjacent alder debris. 118. P. rubicola.
18. Stipe 1.5-3.5 mm thick; spores coffee-color in KOH; spore apex truncate.
119. P. fallax.
18. Stipe 3-8 mm thick. 19
19. Spores deep garnet brown in KOH; pileus grayish clay-color. 120. P. tahquamenonensis.
19. Spores cocoa-brown to tawny in KOH; pileus dark rusty brown. 20
20. Spores dingy ochraceous tawny when first revived in KOH; stipe distinctly
fibrillose-squamulose below veil line. 122b. P. iterata var. ochraceispora.
20. Spores in KOH dark cocoa-brown when first revived; stipe less scaly than
in above choice. (see P. velibrunnescens also) 122a. P. iterata var. iterata.
21. Stipe 1-3 mm thick. 22
21. Stipe 3-6 mm thick. 26
22. Spore apex truncate. 23
22. Spore apex not truncate. 24
23. Growing on barren sandy soil; pleurocystidia obtuse. 124. P. houghtonensis.
23. Growing under larch; pleurocystidia sharply pointed. 123. P. laricina.
24. Brachybasidioles present at maturity. 125. P. fulva.
24. Not as above. 25
25. Outer veil buff-colored; pileus russet. 126. P. similis.
25. Outer veil white; pileus cinnamon to clay color. 127. P. subtenacipes.
26. Pleurocystidia mostly under 50 u long. 27
26. Pleurocystidia often 50, or more long. 30
27. Lamellae grayish brown when mature; stipe grayish in the base. 128. P. subcinerascens.
27. Lamellae rusty to purple-brown; stipe white. 28
28. Stipe 5-10 cm long, on needle duff under conifers. 129. P. microcystis.
28. Not as above. 29
29. Stipe 2-4 cm long; on sandy soil along roads; pileus squamulose at first with outer
veil particles. 130. P. crassulistipes.