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Remarks (internal):Sowerbyella imperialis is known in North America from three collections, i.e. New York (Peck, loc. cit.), west Quebec (above) and central Ontario (L. Rousseau, Sept. 1902, E.T. & S.A. Harper, in F, herb, no. 813). The latter record was brought to our attention by D.H. Pfister of Farlow Herbarium. Seaver (N. Am. Cup-fungi (Opere.), p. 318. 1928) dismissed it as a poorly known species. In Europe and North Africa it has been recorded infrequently and then under Abies sp. and Cedrus sp. (Malençon, Bull. Soc. Mycol. Fr. 95: 128. 1979).
The bright pigmentation, relatively small spores, the orientation of the rectangular cells of the ectal excipulum and broad, loosely woven medullary excipulum distinguish S. imperialis.
Korf (in The Fungi Vol. 4A. Eds. G.C. Ainsworth, F.K. Sparrow & A.S. Sussman. Ch. 9. Academic Press. 1973.) placed Sowerbyella and Caloscypha in the tribe Sowerbyelleae because their carotinoids (Arpin, Bull. Mens. Soc. Linn. Lyon 38: Suppl. 1-169. 1969) are primarily ß-carotene and carotine 444, a pigment unknown elsewhere in the Pezizales. However, there seems to be little morphological similarity between these genera. Eckblad (Nytt Mag. Bot. 15: 86. 1968) placed Sowerbyella close to Otidia on the basis of tissue structure and "hairs" but Otidia lacks carotenoids (Arpin, op. cit.).
Spores cast onto 1.25% malt agar failed to germinate at room temperature after 2 days of cold treatment at 5°C.
Description type:Non-original description 
Description:Sowerbyella imperialis (Peck) Korf, Phytologia 21: 206. 1971.
= Peziza imperialis Peck, N.Y. State Mus. Ann. Rept. 29: 54. 1878.
= Sarcoscypha imperialis (Peck) Sacc., Syll. Fung. 8: 157. 1889.
= Aleuria unicolor Gillet, Champ. Fr. Disco., p. 38. 1879, fide Korf (loc. cit.)
= Geopyxis unicolor (Gillet) Sacc., Syll. Fung. 8: 67. 1889.
= Peziza unicolor (Gillet) Boudier, Bull. Soc. Mycol. Fr. 14: 21. 1898.
= Sowebyella unicolor (Gillet) Nannfeldt, Svensk Bot. Tidskr. 32: 118. 1938.
= Pseudotis unicolor (Gillet) Heim, Bull. Soc. Mycol. Fr. 77: 299. 1962.
Apothecia when fresh to 3 cm diam., hymenial surface orange yellow (Munsell 5YR6/10), plano-concave. Margin slightly wavy to scalloped, pale brown but somewhat dry when collected. External surface yellow (2.5Y8/8), smooth to slightly rugose, matted tomentose. Stipe pallid (2.5Y8/4), to 5 cm long, 3-4 mm diam., broadening to 8 mm at the apex, mostly covered by adhering leaves and woody debris, with a yellow densely cottony interior and thin, pale brown rind. Flesh yellow (2.5Y8/6), 1-1.5 mm thick, no latex or sap when cut. Medullary excipulum a loosely interwoven textura intricata with broad, thin-walled, branched, pale yellow hyphae, 6-14 µm diam. which are swollen and oriented perpendicularly to the surface where they intergrade into the ectal layer. Ectal excipulum a textura globosa to textura angularis composed of isodiametric to rectangular, thin-walled, pale yellow to orange cells, 16-25 µm wide and up to 42 µm long which retain some linear orientation perpendicular to the surface. Hairs subhyaline to pale yellow, cylindrical, 3-5 µm diam., often with an abruptly swollen base 8-10 µm diam., thin-walled, septate, with obtuse apex, up to 240 µm long, often branched at the base, arising from short-celled hyphae, ca. 7 µm diam., which are often inflated to 10-20 µm diam. in the outer layers of the ectal excipulum. Asci octosporous, operculate, cylindrical, thin-walled, 170-180 x 6.5-8.5 µm, the apex not bluing in Melzer's reagent. Paraphyses filiform-clavate, septate, narrowing slightly and branched toward the base, usually with a slightly swollen apex, 3.6-4.5 µm wide, projecting slightly above the asci, filled with numerous, orange globules. Ascospores obliquely uniseriate, narrowly ellipsoid, biguttulate or triguttulate, (11.2-)12-13 x 4.8-5.6 µm, ornamented by numerous, solitary, low (-0.4 µm high), cyanophilic warts.
Substrate: Rotten leaves, twigs and bark, especially of Ulmus americana L.
Distribution: Quebec.
Taxon name: