The North American Species of Crepidotus

110. Crepidotus cesatii (Rab.) Sacc., Michelia 1: 2. 1877.

Agaricus cesatii Rab., Fl. Ratisb., p. 564. 1851.

Illustration: Fig. 184.

Pileus 5-20 mm broad, pure white, sessile or nearly so, cupulate, then conchoid and reflexed, base often bilobed, villose, fibrillose behind, margin involute, villose. Context thin at the margin, thicker at the center, soft, white; odor and taste mild or none.

Lamellae radiating from a lateral or eccentric point, white, then pale flesh-color, finally rusty-flesh color to rusty, with numerous lamellulae, medium broad, moderately close.

Spores (6.5) 7-9 (10) x 5.5-7 (7.5) µ, broadly ellipsoid, punctate-echinulate, pale yellowish-brown in 2% KOH. Basidia (18) 25-32 x 6-8 µ, 4-spored. Pleurocystidia none; cheilocystidia 28-50 x 6-7 (10) µ, contorted, forked, knobbed, subcylindric, ventricose. Gill trama subparallel, hyphae 6-12 µ broad. Pileus trama interwoven. Cuticle of repent hyphae, or at times not sharply differentiated, the surface bearing a turf of colorless hyphae, 3-4.5 (6) µ broad. Clamp connections present.

Habit, Habitat, and Distribution: On hardwood and conifer wood, Europe, summer and autumn.

Material Studied: CZECHOSLOVAKIA: Pilát 23173,23456,23457, 149096, 487852, 487965, 488570 (PR); NETHERLANDS: Reijnders, on Salix, Oct. 31, 1954 (L).

Observations: The very broad, more or less echinulate spores, contorted cheilocystidia, and straight epicuticular hyphae are distinctive characteristics of C. cesatii. On a basis of material we have seen, C. cesatii differs from C. sphaerosporus, which has shorter spores and crooked or coiled epicuticular hyphae. Thus far, we have seen no material of C. cesatii from North America, but we include it here for comparison, and in the hope that it might later be found here.