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Page number:107 
Description type:Non-original description 
Description:Poria medulla-panis (Jacq. sense of Pers.)Bres. Fig. 92
Accad. Rover. Agiati Atti 3 (3):84. 1897. Poria medulla-panis Pers.,
Neues Mag. f. Bot. 1:109. 1794. Boletus medulla-panis Jacq, Miscel. Austr. 1:141. 1778. Polyporus tremor Berk. & Curt., Hooker's Jour. Bot. 1:104. 1849. (K; BPI; FH; S). P. xylostromatis Fuckel; Nassuicher Ver. Natur. Jahrb., 27 & 28:86. 1873. P. limitatus Berk. & Curt., Grevillea 1:54. 1872 (K; BPI; FH; NY). P. dryinus Berk. & Cooke, same, vol. 6:130. 1878 (K; BPI; NY). Poria amara Burt, n. nudem, in Bresadola, Studi Trent. 2 (7):80. 1926. "P. unita (Pers. ) Karst." of many writers.
Perennial up to 3-4 years, becoming widely effused, up to 10 mm thick, separable or adnate, usually bitter; margin white to cream or sometimes more or less brown, arachnoid or fimbriate to matted, narrow to wide; pore surface white or sordid white, occasionally somewhat yellowish on drying, dull, the tubes firm or corky when fresh, drying hard and brittle or leathery, up to 2.5 mm long in each layer, the layers indistinct to distinct, pores round to angular, about 5-8 per mm, edges remaining thick or rather thick, entire; context white, soft-corky when dry, thin, continuing without change into the trama, becoming indistinct when the adjoining tube tissue becomes stuffed.
Tissue not changing color in KOH; hyphal system somewhat uncertain, probably trimitic, the context apparently of intricately branched, thickwalled to solid, nonseptate (?)binding hyphae 1.5-3 µm in diameter or occasionally inflated to 7 µm and often tapering to a fine point, of (?) skeletal hyphae which are similar except unbranched or rarely branched, and of generative hyphae which are often branched, thin-walled, infrequently nodose-septate (perhaps also simple-septate?), 2-3 (-4) µm in diameter; trama continuous with the context and the hyphae similar; hymenium 9-14 µm; thick; hyphal pegs present; cystidioles sometimes present, imbedded, inconspicuous, 3-7 µm. in diameter; basidia clavate, 9-12 x 6-9 µm; spores hyaline, smooth, IKI -or reddish brown (dextrinoid), walls often thickened, oblong-ellipsoid to oval or subglobose, usually truncate, 4-7 x 2.5-5 µm.
On angiosperms or rarely on gymnosperms and very widely distributed; associated with a white rot, see Findlay in Brit. Mycol. Soc. Trans. 34:36. 1951.
The name Poria unita (formerly used for this fungus) seems inapplicable, because a specimen in the Bresadola collection at Stockholm, annotated by Bresadola as "fragm. type", is P. megalopora Pers. The name "medulla-panic" is favored by Donk on the basis of specimens in the Persoon Herbarium at Leiden (1960, p. 266). The name Poria medullaris S. F. Gray is also used for this fungus. P. f ulviseda Bres., from France, is extremely similar and may be a thicker, softer form with somewhat smaller spores than usual, 4-5 x 2.5-3.5 µm. P. alboincarnata (Pat. & Gaill.) Sacc., from Venezuela, is very similar except it seems to differ in having simple-septate generative hyphae, and P. roseoisabellina (Pat. & Gaill.) Sacc. from Venezuela, differs principally in having pores about 2 per mm.
It is very likely that more than one species is included in the concept accepted here. P. tenuis and P. subacida intergrade with this species and the synonomy, particularly the several species proposed by Berkeley, must be considered provisional. P. medulla-panic, in southern and tropical areas, is often truly reflexed and can be referred to the genus Fomes.
This species was selected as the type for the genus Poria by Persoon in 1794 and made the lectotype by Donk in 1949, as type for genus Perenniporia by Murrill, and type for the genus Poria as emended by M. C. Cooke.
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