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E R IN E U M GRISEDM.
P u rp lish -g re y Erineum.
C l a s s a n d O r d e r CRYPTOGAMIA FUNGI, Linn.—N a t . O r d . G A S T ROM YC I,
GrCT—MUCEDINES, Link.
G EN ERIC CHARACTER.
Peridia Jhccifarmia, subdiaphana, varia, subsimplida, aggregato-caespitosa, f o liis
vivis parasitica. Spondee niinutissimoe, sæpissime subnullæ.
Peridia flocciform, subdiaphanous, various, subsimpie, aggregato-cæspitose,
parasitic on iiving ieaves. Sporuies most minute, very frequentiy in-
visibie.
S P E C IF IC c h a r a c t e r .
E rineum g ris eum ; hypophyllum, late effusum, sericeum, purpurascenti-griseum;
peridiis rninutissimis, numerosissimis, clavatis.
E. on the iower surface of the ieaf, broadiy effused, sericeous, purpiish-
grey ; peridia excessiveiy minute and numerous, ciub-shaped.
E rineum griseum , Pers. Mycol. Europ. 1. p. 8— Kunze, Mykol. Hefte, 2. p. 135.
—Grev. Fl. Edin. p. 449.
E rineum minutissimum, Grev. hi Edin. Phil. Journ. v. 6’. p. 81. t, 3. f. 15.
H ab. On th e leaves of the Oak, not unfrequent. Spring and summer.
The first commencement of this plant is nothing more than a reddish or
purplish stain on the inferior surface of the leaf. In a short time the
central portion becomes developed, and assumes a grey colour, and minutely
silky or rather velvety appearance. Under the microscope, the
peridia are found to be of a nearly uniform shape, obtusely clavate,
perfectly simple, and excessively crowded.
Like most species of Erineum, the present one is remark-
ahly gregarious, and when it has once taken possession of a tree,
scarcely allows a leaf to escape. The spots of aggregated plants
have no determinate figure, but spread irregularly over the surface
so widely as sometimes to obliterate all trace of the original
colour.
Fig. I. a, E. griseum, nat. size, h, Peridia. c. Ditto; the two last magnified.