May 26,1923 
Graminicolous Species of Helminthosporium 
681 
by its smaller dimensions, thicker peripheral wall, and absence of attenu¬ 
ated apical prolongation. 
Although not much importance can be attributed to the length of 
the conidiophores as a diagnostic characteristic, it may not be super¬ 
fluous to mention that in the species under consideration these struc¬ 
tures show a rather usually wide range in this dimension. This vari¬ 
ability apparently is less due to differences in length of intervals between 
the points of insertion of successive spores than to pronounced differences 
in length of the sterile portion below the insertion of the first conidium. 
It is not difficult to suppose that changes in environmental conditions are 
responsible for either greater or lesser development of the sporophore 
preliminary to the proliferation of the first conidium, resulting in con¬ 
ditions like those illustrated in Plate 12, Fe-j, on the one hand, and like 
those figured in Plate 12, Fa-d, on the other. 
A fungus quite indistinguishable from the form on Italian rye grass 
was found to occur abundantly in Virginia and Maryland on the closely 
related host, Lolium perenne. An examination of numerous specimens 
of diseased perennial rye grass collected near Annapolis in May, 1921, 
and in the vicinity of Washington, D. C., during the months of May 
and June, 1922, revealed no constant or significant morphological charac¬ 
teristics by which the form parasitic on this forage crop could be dis¬ 
tinguished from the parasite on Italian rye grass. In the absence of 
any cross-inoculation work the writer is inclined to regard the fructifi¬ 
cations on the two hosts as belonging to the same species of Helmintho¬ 
sporium. It must be noted, however, that the attack of the fungus on 
L. perenne is usually not associated with the conspicuous spotting of the 
leaves readily observed on affected foliage of L. multifiorum, the dis¬ 
coloration being generally less evident and in many instances scarcely 
demonstrable. In the latter event, the withering of the foliage due to 
the parasite is, without microscopical examination, not very easily 
distinguished from the vegetative decline associated with drought or 
normal ripening. 
As a large proportion of the leaves of the two species of Lolium are 
killed prematurely, it is safe to assume that the parasite interferes with 
the development of the plants sufficiently to cause appreciable economic 
loss. According to the writer's observations, the leaf disease attributable 
to the parasite constitutes the most destructive fungus trouble affecting 
the two valuable forage grasses in Maryland, Virginia, and the District 
of Columbia. That it has hitherto apparently escaped the attention of 
American pathologists is indicative more, perhaps, of neglect of diseases 
destructive to the graminaceous forage crops than to a possibly limited 
distribution. 
It is interesting to note that in 1903 Diedicke (29) made mention of the 
occurrence of a species of Helminthosporium on Lolium perenney causing 
a local infection similar to that occasioned, for example, by Helmintho¬ 
sporium hromi or //. teres on their respective hosts. No further description 
was given, and this investigator, after failing to connect the fungus with 
any ascigerous stage, apparently paid no furtlier attention to it. Whether 
the American fungus is the same as that observed by Diedicke in Germany 
is a question open to conjecture. In any case, it appears not to have been 
described; and it evidently is distinct from the o^er species parasitic on 
grasses studied by the writer. It appears expedient to recognize it as a 
species, for which, because of its pathological effect on the foliage of its 
hosts, the specific name siccans is proposed. 
