May 26, 1923 
Graminicolous Species of Helminthosporium 
729 
HEl^MINTHOSPORIUM CYCLOPS, N. SP. 
In July, 1921, the writer collected, near Lisbon Falls, Me., specimens 
of Danthonia spicata (L.) Beauv. that appeared to be slightly affected 
with a leaf spot of the type caused by Helminthosporium sativum. 
Although the grass had completely headed and most of the lower basal 
leaves were dead, the remaining foliage was still green and in an actively 
vegetative condition. The dark brown or black foliar lesions, usually 
not exceeding 0.5 by 2 mm. in length, were found distributed very 
sparsely over the living foliage. On the dead basal leaves correspond¬ 
ing spots were observed, although considerably faded; and in a number 
of instances microscopic examination revealed these as the foci of 
fructifications of a species of Helminthosporium differing markedly 
from a small-spored congeneric form that also was present in moderate 
quantity. Although the fructifications of the former species were not 
confined to the conspicuously discolored areas, their distribution on the 
dead leaves was such as suggest a causal relation between the fungus 
and the brown foliar lesions. Owing to the small size of the leaves of 
Danthonia spicata and the tendency of the foliage to begin withering early 
in the course of the growing season, the matter of referring such type of 
foliar discoloration to a fungus not appearing on the surface until after 
the death of the tissues involved, and then not in great abundance, is 
attended with some uncertainty, as has been noted in another connection. 
The possible damage resulting to the host from the leaf spot in any case 
would appear to be quite insi^ficant. 
The conidiophores (PI. 32, Ea-c) of the fungus are not especially 
characteristic, and show little to distinguish them from those of Hel¬ 
minthosporium sativum or H. vagans^ in size, color, or general appearance. 
The conidia (PI. 32, ca-m) also resemble the analogous structures of 
these two species in possessing, when mature, a conspicuously thick 
peripheral wall, and, associated with this thick wall, a dark olivaceous 
color. In length they are approximately equal to the conidia of H. 
sativum and not greatly inferior to those of H. vagans; while in diameter 
they fall slightly below the spores of the former species and more con- 
siderablv below those of the latter. Uniformly straight, and either nearly 
cylindrical or tapering more perceptibly toward the ends, they perhaps 
resemble most closely the spores of H. vagans in general shape. A specific 
difference readily distinguishing the spores of the iorm on Danthonia 
spicata from those of H. sativum and H. vagans is found in the more 
pronounced attenuation of the peripheral wall at the base and apex. 
The basal end, moreover, is distinguished by a conspicuous hilum, the 
largest observed in any species reported in this paper, which, because of 
a somewhat fanciful resemblance to an eye, has suggested the specific 
name cyclops. 
The conidia (PI. 32; Da, b) germinate readily in water, producing two 
polar germ tubes, which emerge, as might be anticipated, from the 
hyaline, thin-walled regions at the tip and immediately surrounding the 
hilum. In mode of germination the fungus thus again resembles 
Helminthosporium sativum. That the relationship with the latter species 
nevertheless is not a very close one is indicated in agar cultures, by the 
development from the imbedded mycelium of an abundance of inflated 
elements altogether analogous to those observed, for example, in cul¬ 
tures of H, tritici-repentisy H. hromi, H. teres, and H. turcicum. On 
potato-dextrose agar a moderately profuse gray aerial mycelium is 
