Fig. I. a, ..i portion o f an Elm-leaf, with D. Ulmi, natural size, b, A single pdant
or receptacle, c, A portion an old receptacle represented, part o f it having
fallen amay. d, A section o/' a part o f a receptacle in a 7-ather young state,
shewing the simple cellules, e, Thecoe and sporidia, magnifed-
DOTHIDEA BETULINA.
Birch-leaf Dothidea.
S PEC IF IC CHARACTER.
D o t h id ea betulina ; “ epiphylla angulato-difformis, subconfluens, tuberculosa,
alro-nitens, intus nigra, cellulis albis."—F r ie s .
D. epiphyllous, somewhat angular and irregular in form, subconfluent, tuberculose,
black, shining, black within, the cellules white.
D o t h id ea betulina. Fries, Syst. v. 2. p. 554.
X yloma betulinum. Fries, Óbs. Mycol. 1. p. I 98.—D e Cand. Mem. Mus. III.
p. 319. t. 3. f. 1.—Funck, Exsicc. No. 382.—Moug. et Nestl. Stirp. Exsicc.
No. 370.
X yloma p o p u lin um , Schum. Sælland, 2. p . V ig .fd e Fiies.
S p h æ r ia xylomoides. Fries, in Ac. Vet. Handl. 1816, p. 143.— Sclerom. Suec.
No. 144.
S p h æ r i a atro-nitens, HoU, et Schmidt, Deutschl. Schwaem. No. 29.
S ph æ r ia Betulæ nanæ, Wahl. FI. Lapp. p. 143. t. 30. f. 3.
H ab. On the living and dead leaves of the Common Birch (Betula alba) ,
in summer and autumn, not unfrequent. Common in the Highlands of
Scotland, where birch trees are plentiful. On the dwarf Birch ( B. nana) ,
more rare, Mr W a l k e r A r n o t t .
Receptacles very numerous, scattered, or a good deal crowded, minute, very
irregular in form, and several often running into each other, very black,
smooth, and shining ; the surface rendered uneven and tuberculated by
the inclosed cellules, which are large for the size of the plant. Cellules
round, white within, containing linear-clavate thecæ, which inclose a
few globose sporidia.
This plant, as well as the preceding, is a true Dothidea,
answering extremely well to the generic character of M. F r i e s .
It belongs to the Xyloma division of the genus, in which my
friend above named has included the Sphæria typhina of authors,
a situation, I fear, it can scarcely expect to hold, having
real perithecia.
Fig. 2. a, A leaf o f Betula alha, with D. betulina, natural size, b. Receptacles.
c, A receptacle transversely divided, d, Thecæ and sporidia,— magnif ed.