The North American Species of Crepidotus
13. Crepidotus mollis var. mollis (Fr.) Staude, Die Schwämme Mitteldeutschlands, p. 71. 1857.
Agaricus mollis Fr., Syst. Myc. 1: 274. 1821.
Agaricus (Crepidotus) fulvotomentosus Pk., N.Y. State Mus. Nat. Hist. 26: 57. 1874.
Agaricus haerens Pk., N.Y. State Mus. Ann. Rept. 35: 132. 1884.
Crepidotus calolepidoides Murr., Mycologia 5: 30. 1913.
Crepidotus mollis var. calolepis (Fr.) Pilát, Acta Musei Nat. Pragae 2B: 74. 1940.
Pileus 1-5(8) cm broad, sessile, reniform to obovate, soon plane, with a gelatinous cuticle, flaccid, brownish fibrillose or scaly to apparently glabrous, hygrophanous, olive brown (moist), becoming shining and ochraceous-whitish (dry), margin faintly striatulate. Context thin, white, odor mild, taste mild or more rarely bitter.
Lamellae decurrent, radiating, whitish, becoming cinnamon, broad or moderately broad or moderately narrow, crowded to close, the edges at times gelatinous and fimbriate.
Stipe none, or rudimentary and obsolete.
Spores 7-9 (10) x 4.5-5.5 (6) µ, ellipsoid in face view, slightly inequilateral in profile, smooth, brownish in 2% KOH, wall double. Basidia 23-34 x 5-7 µ, 2-4-spored. Pleurocystidia none; cheilocystidia of two types: (1) hymenial, 30-60 x 6-8 µ, flask-shaped to irregularly cylindric; (2) tramal, 70-105 x 4-6 µ, filamentous, the apices often more or less enlarged, gelatinous, in Sm-42732 the tips may be contorted. Gill trama subparallel, at times the hyphae irregularly branched, 4-9 µ broad. Subhymenium of parallel, narrow hyphae. Pileus trama interwoven, hyphae 5-12 µ broad. Cuticle a distinct gelatinous zone, 130-500 µ thick, the hyphae interwoven and narrow (1.5-2 µ), the surface bearing repent to erect tufts of fuscous or colorless hyphae, some of the former incrusted. Hypodermium distinct. Clamp connections none.
Habit, Habitat, and Distribution: On bark of deciduous, more rarely coniferous, trees, in the temperate zones of North America, South America, The British Isles, Europe; spring, summer, and autumn.
Material Studied: IDAHO: Smith 53835, 55309, 55311; MAINE: Bigelow 10569; MASSACHUSETTS: Bigelow 8251; MICHIGAN: Iltis (TENN-18251); Johnson 1649 (MICH.); Smith 11129, 18949, 21735, 25468, 33691, 42732, 49596, 49597, 49601, 49637, 49758, 49759, 49760, 49761, 49762, 50997, 51942, 57068, 57087a,57691, 57707, 63499, 63506, 63581, 63585, 63588, 66277, 66306, 66332, 6634 663466349, 66363, 66382, 66389, 66390, 66392, 66653, 66672, 66701, 67456; NEW HAMPSHIRE: Bigelow 11754 (MASS); NEW MEXICO: Barrows 249, 1288 (MICH); NEW YORK: Peck, type (NYS) of Agaricus (Crepidotus) fulvotomentosus, from Savannah, August; Peck, type (NYS) of Agaricus (Crepidotus) haerens, from Albany, September; NORTH CAROLINA: Hesler 20950, 25686; OHIO: Smith 32984, 33356, 33762; OREGON: Smith 20232, 28561, 28571; TENNESSEE: Hesler 5446, 9040, 11450, 11548, 17475, 18251, 19232, 21666, 21847, 24421, 25764; WASHINGTON: Pilát 23489 (PR), collected by Y. M. Grant, Sept., 1926; Smith 13704, 13928, 17947, 28925, 28927, 29369, 39861, 47825, 48482; ECUADOR: Rose 27364 (as C. calolepidoides, NY); JAMAICA: Murrill 556 (NY), type of C. calolepidoides, from Cinchona, 1908-9; ENGLAND: Reid & Donk, Burham Beeches, 6-10-57 (K); H.R.D. Ilston Valley, 19-10-14 (K); Dennis, Norbury Park, Surrey, Nov. 4, 1945 (K); Kew-3644, Haslemere, Oct. 1913 (as C. mollis var. calolepis); SCOTLAND: D. Boths (K), Fort William, Aug. 28,1956; Reid (K), Killiecrankie, Aug. 26, 1953; FRANCE: Smith 66264, leg.-det. Josserand; NETHERLANDS: Hesler 26101 (leg. C. Bas), 26102 (leg. Maas Geesteranus): CZECHOSLOVAKIA: Pilát (PR) 149083, 193926, 20565, 23487, 23496, 23503; SWEDEN: Lundell 23453 (UPS), as C. calolepis; Lundell & Nannfeldt 907 (UPS), Goteborg; Pilát 14465, Stockholm; Romell 1891 (NY).
Observations: The material examined, both European and American, shows wide variation in the abundance and density of the brownish fibrils and scales. In a given collection, one pileus may be very densely fibrillose, and another very lightly so, and in the latter instance appearing to the unaided eye as glabrous. Thus, it is understandable that C. mollis has at times been described as glabrous. In C. haerens, Peck originally described the pileus as glabrous, but the type clearly shows some brownish, erect, incrusted, epicuticular hyphae. In Peck's C. fulvotomentosus, the pileus is densely fibrillose, and these fibrils are brown, incrusted hyphae, as in mollis. Again, the pileus of C. calolepidoides was originally described by Murrill as beset with small conic elevations (scales); but, in the type, these scales were found to be composed of brownish, incrusted hyphae, as in mollis. The pileus of C. calolepis is described as fibrillose scaly. In European material we have seen the pileus bears brownish incrusted hyphae, again as in mollis. In view of the variation in C. mollis, the density of these brown incrusted hyphae does not offer a stable basis for the separation of haerens, fulvotomentosus, and calolepidoides from mollis. The material of calolepis we have seen is not different from mollis.
The structure of the gelatinized cuticle, and the morphological characters of the spores and cheilocystidia, are valid characters; but likewise, none of these characters provides a basis for separating the Peck and Murrill entities, listed in synonymy, from mollis.
In most of our collections, the spores are 7-9 (10) x 4.5-5.5 (6) µ. In a few collections (Shaffer-674; and Smith-63506 and 66264), the spores are about 1 µ shorter than in most collections; and in Smith-25468 and 31963, the range is from 6-9 x 4.5-6 µ. Otherwise, these collections exhibit the distinguishing characters as found in all other collections of C. mollis.