The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Spores 10-13 x 5.5-6.5 u, smooth, truncate from a broad apical pore, shape in
face view ovate-pointed (at apiculate end) to elliptic but pointed somewhat at
apiculate end, in profile somewhat to obscurely inequilateral, color in KOH date
brown, paler when immature, dark date-brown when mature, in Melzer's tawnyred to bay, wall about 0.16 au thick.
Basidia 4-spored, hyaline in KOH, 10-12, broad, hyaline, readily collapsing.
Pleurocystidia and cheilocystidia none or a few clavate hyaline cells present as
the latter.
Gill trama hyaline in KOH. Pileus trama slightly yellowish to sordid tawny
in KOH for the subcuticular region. Cuticle a layer of inflated cells 2-3 deep;
the walls thin, smooth and hyaline. Clamps present.
Type locality. Highland Cemetery, Geary County, Kansas.
Habit and habitat. Cespitose on herbaceous stems and decaying vegetation in
the soil.
Distribution. Known only from the type locality.
Observations. The grayish brown color of the pileus when young but drying
clay color, white stipe, slight veil, and the spores somewhat pointed at the
apiculate (basal) end, appear distinctive in this subsection.
Series Atricastaneae A. H. Smith, ser. nov.
Sporae 5-10 t longae. Typus. Psathyrella atricastanea.
Observations. The presence or absence of pleurocystidia has not been finally
ascertained for a number of southern species because it was impossible to revive
sections of the types well enough to give reliable data. These species are placed
here because no evidence of pleurocystidia was obtained, and because there
appears to be a rather large group of southern taxa lacking these structures. For
additional species possibly lacking a veil see Candolleanae.
Key to the Species of Series Atricastaneae
1. Spores lemon-shaped but smooth. 240. P. diminutiva.
1. Spores not as above. 2
2. Spores when first mounted in KOH nearly hyaline to ochraceous-hyaline. 3
2. Spores in KOH cinnamon, avellaneous or darker. 7
3. Spores 7-9 X 4-5 4
3. Spores smaller. 5
4. Pileus dark chestnut-brown at first; on buried wood, Cuba. 241. P. atricastanea.
4. Pileus merely dull dingy yellow-brown, on humus, U.S.A. 242 P. subhyalinispora.
5. In Melzer's the region next to and including the subhymenium of the hymenophoral
trama orange-red in revived mounts. 243. P. hoseneyae.
5. Not as above. 6
6. Lamellae broad; stipe shining white. 244. P. albipes.
6. Lamellae narrow; stipe white (see 44. P. singeri also) 245. P. musae.
7. Spores 5.5-6.5 X 3.2-3.8 ps, stipe snow white. 246. P. plana.
7. Spores larger (if cespitose see 348. P. multipedata also) 8
8. Lamellae narrow. 9
8. Lamellae broad (use mature basidiocarps). 11
9. Pileus grayish brown then argillaceous; spore apex not truncate. 247. P. campestris.
9. Spore apex truncate (or pore "bubble-like" revived in KOH). 10
10. Pileus pale chestnut color; spores 4.6-6,/ wide. 248. P. castaneidisca.
10. Pileus pale fawn-color; spores 4-5 u wide. 249. P. australis.
11. Stipe base furnished with a conspicuous mass of tomentum; spores with a distinct
apical pore. 250. P. byssina.
11. Not as above. 12
12. Terrestrial. 13
12. Lignicolous. 14