The Botany of Iceland - 01.12.1932, Síða 25

FUNGI OF ICELAND
473
raany different host-plants, its density is much less than in Central
Europe. In this respect it falls far short of Pyrenophora chrtjsospora.
As is well known, Pleospora herbamm is a very polvmorphous species,
especially with regard to the dimensions of the perithecia, asci and
spores. Bul the species is variable in other respects, too. On Saxi-
fraga corniculata, Primula veris, Pulsatilla vulgaris and Poly-
gonatum multiflorum the spores of P. herbarum may have a wide
coating of mucus. OnLotus corniculatus, on which ])lant the peri-
thecia may be found on the stem as well as the pods, I have found
4-spored asci on the stem, and at the same time 8-spored asci on the
pods. The spores in the 4-spored asci were 48—50X18—20/1, whereas
the spores in the 8-spored asci measured 30—50X14—15,11. Typically
the upper and lower halves of the spores are asymmetrical, but on thin
dead branches of Hippophaés rhamnoides, where P. herbarum also
occurs, these halves are symmetrical If these deviations from the type
are constant, the species P. herbarum should rightly be divided into
several species, but as this has by no means been established, I have
included the various Icelandic forms under one species.
The most divergent forin of P. herbarnm which I have seen in Ice-
land, is that occurring on Rumex acetosella, which has both spore-
ends somewhat acuminate, whiie the breadth of the spores is small com-
pared with their length, the dimensions being 33—36XH—12/x; hence
the proportion of length to breadth is 3 in this case, whereas the typical
value of this ratio ranges from 2 to 2.5.
Leptosphaeria Cesati et De Notaris.
81. L. Equiseti Karsten, Fungi in insulis Spetsbergen, p. 101. Stock-
holm 1872.
Tröllafoss [Svend Andersen]; Hallormstaðir, the plantation at Grund
south of Akureyri, Almannagjá near Þingvellir [P. L.]. — On withered
pieces of the stem of Equisetum variegatum.
In the literature two different views of this species prevail. However,
Karsten’s description of L. Equiseti in Mycologia Fennica II, Pyrenomy-
cetes. p. 101, will perhaps cover both of them. In The Micromycetes of
Svalbard, Skrifter om Svalbard og Ishavet, N. 13, Oslo 1928, Pl. II, tigs.
15a and 15b, J. Lind has given a figure of the asci and spores of L.
Equiseti Karsten, which agrees perfectly with the Leptosphaeria, found
on Equisetum variegatum in Iceland. But a different conception of L
Equiseti Karsten has been given by Berlese in Icones Fungorum.
Pyrenomycetes Vol. I, p. 54. The Leptosphaeria figured here by Berlese
shows considerable deviation, in regard to the dimensions botli of the
asci and the spores, and especially in regard to the form of spore, from
Lind’s Svalbard form and from the Icelandic form. On the other hand,
thc diagnosis given in Berlese’s figure agrees with a Leptosphaeria, which
is very common — at any rate in Denmark — on Equisetum hiemale,
where it grows on the dead internodes of the stems so common at the
apices of the stems in all growths of Equisctum hiemale. It must,
however, be supposed that Berlese received the material for his flgure
of this Leptosphaeria from Karsten, and that Karsten must have in-