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Page number:243 
Remarks (internal):Care must be taken not to confuse C. anceps with another related form which is not uncommon. One occasionally finds a Corticium in fruiting condition on the bases of stems of living ferns or of angiosperms. Sometimes this fungus may form a very delicate whitish film of mycelium and basidia not only on the stems or petioles but extending over considerable areas of the under surface of the living leaves. There is however in such cases no evidence of parasitism. The fungus is apparently growing superficially over the host, presumably spreading as a saprophyte from surrounding humus. No mycelial pads or sclerotia such as occur in C. anceps are formed and the host appears not to be affected. We have collections of this form from Bear Island, Lake Timagami, on the bases of stems of Pteridium aquilinum var. latiusculum, Dryopteris Phegopteris, Onoclea sensibilis, Aralia nudicaulis, Diervilla Lonicera, Aster macrophyllus, seedling Fraxinus nigra, and on stems and leaves of Viola sp., Rubus pubescens, and on an unidentified grass. A collection of the same form was also made at Inlet, New York, in 1934 on petioles and leaves of Rubus pubescens and on rachis and fronds of Onoclea sensibilis. While showing some variation in spore size and diameter of mycelium these collections are all referred, for the present, to Ceratobasidium cornigerum (Bourd.) Rogers (= Corticium cornigerum Hourd.) which, as at present interpreted, is also commonly found as a saprophyte on (lead bark and wood of various trees. This species does not form sclerotia or appressorial pads in culture. It is quite different from C. Solani though fruiting in a similar relation to the host and has perhaps sometimes been confused with that species. Mrs. Gregor (7, p. 403) refers briefly to another Corticium which she found at the base of bracken fronds in connection with her studies of C. anceps, which appeared to be quite harmless. It is possible that this may also have been C. cornigerum, though no description was furnished, and the species was not identified. 
Description type:Non-original description 
Description:Ceratobasidium anceps (Bres. & Syd.) comb. nov.
Tulasnella anceps Bres. & Syd., Ann. Mycol. 8 : 490. 1910.
Sclerolium deciduum J. J. Davis, Trans. Wisc. Acad. Sci. 19 : 689. 1919. Corticium anceps (Bres. & Syd.) Gregor, Ann. Mycol. 30 : 464. 1932.
Basidial fructification occurring as a delicate, closely appressed, often almost invisible film or weft of hyphae spreading over the apparently uninjured lower surface of the leaves of the host, usually observed as occurring at the margin or in advance of spreading necrotic lesions; sometimes developing sufficiently to form a delicate separable pellicle. The film or pellicle made up of intertwining, branching, thin-walled, simple-septate hyphae 3.5-5.5 µm in diameter, branching often at right angles. Basidia short cylindric, broadly clavate, obovate, or irregular, 10-18 x 8-12 µm, often formed directly from hyphal cells when they may have a truncate base drawn out at either side or to one side if formed terminally. "Epibasidia", usually four, occasionally three, developing at first as subglobose projections, becoming cylindric and finally terete, arcuate, or rather widely divergent, 10-16 µm long. Basidiospores asymmetrically ellipsoid, broadest below the middle, flattened and appearing straight on one side, with prominent lateral apiculus, varying somewhat in size on different hosts, 9-13 x 4.5-7 µm, germinating by repetition; walls thin, smooth, nonamyloid (Fig. 1).
Following the advancing basidial fructification and often beginning to appear before basidial production has ceased, the hyphae become aggregated at close intervals into what may be termed appressorial pads or infection cushions (Gregor). As these develop the hyphae intertwine closely with septa at frequent intervals. At maturity a compact palisadelike layer of parallel hyphal tips develops on the side next the host epidermis with looser intertwined threads on the free side. Necrotic tissue develops as the cushions mature and the latter persist on the dead areas as brownish specks and furnish a positive means of identification after the basidial fructification has disappeared.
Finally white fluffy masses of mycelium are developed on the surface of the dead areas at irregular intervals and these are gradually transformed into the characteristic brown sclerotia which, when frilly developed, are deciduous.
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