[Vol. 12 

 286 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Specimens examined: 

 Oregon: Waltersville, C. C. Epling & J. B. Shorett, 600, type, 

 comm. by S. M. Zeller, 2317 (in Mo. Bot. Gard. Herb., 

 63041). 



4- 64. P. crassa Burt, N. Y. State Mus. Rept. 54: 155. 1901. 



Stereum Karstenii Bresadola, I. R. Accad. Agiati Atti III. 3: 

 108. 1897; Bourdot & Galzin, Soc. Myc. Fr. Bui. 37: 126. 

 1921. Not Peniophora Karstenii Massee, Linn. Soc. Bot. Jour. 

 25: 153. 1889. Not Phanerochaete odorata Karsten, Finska 

 Vet.-Soc. Bidrag Natur och Folk 48: 427. 1889. Corticium 

 ochroleucum, in part, of Berkeley & Curtis, Grevillea 1: 165. 

 1875, but not of Fries. 



Type: in Burt Herb. 



Fructifications broadly effused, becoming thick, somewhat 

 fleshy, light buff to pinkish buff, separable from the substratum 

 when moistened if thick, the margin somewhat tomentose, deter- 

 minate; in section 500-1500 pi thick, not colored, 2-layered, with 

 the layer next to the substratum 200-300 pt thick, composed of 

 densely interwoven, rather thick-walled and stiff, non-incrusted 

 hyphae 3-4J^ y. in diameter, and with the hymenial layer 300- 

 1200 [i thick, more or less zonate, and composed of erect hyphae 

 and cystidia; no gloeocystidia ; cystidia even or sometimes some- 

 what incrusted, cylindric, flexuous, 100-500 X 43^-6 \l, pro- 

 truding up to 30 [l beyond the basidia, present in all parts of the 

 hymenial layer, destroyed and dissolved by potassium hydrate 

 treatment of sections; basidia 4-spored; spores white in spore 

 collection, even, curved, 43^-6 X lJ/-2 \i. 



Fructifications 3-20 cm. long, 1-4 cm. wide. 



On decorticated, decaying logs of Pinus, Abies, Picea, Tsuga, 

 and Pseudotsuga. In Europe and from Canada to Alabama and 

 westward to the Pacific states. Common. 



P. crassa is certainly cogeneric with P. glebulosa, belongs in the 

 same group of species, occurs on the same substrata and is prob- 

 ably equally destructive to wood. Its fructifications are thicker 

 than those of P. glebulosa and crack into larger masses. The 

 cystidia have thinner walls and larger lumen than those of P. 

 glebulosa and are noteworthy for the destructive action of potas- 



