May 26,1923 
Graminicolous Species of Helminthosporium 
723 
rate, no species of Helminthosporium having canidiophores with the 
swollen pestle-like tip mentioned in the diagnosis of H. hadotrichoides was 
found. However, a fungus obviously belonging to the genus was ob¬ 
served with considerable frequency on the dry leaf blades. As the form 
has never been found occurring on other grasses, it would appear to be 
more or less closely restricted to Eragrostis major. The mature condition 
of the grass precluded any inquiry into the biological relation of the fungus 
to its substratum; so that the present account is necessarily confined to a 
discussion of morphological facts. 
The conidiphores (PI. 29, Ca~h), which are of moderate dimensions, 
differ in no important detail from those of many other congeneric grami¬ 
nicolous species. They show usually a pronounced tendency to fuse at 
the base, the whole cluster often appearing to arise from a single super¬ 
ficial basal portion communicating with file mycelium within the leaf 
structures by hyphal connections passing through stomata or between 
adjacent epidermal cells. A similar tendency has been observed not 
infrequently in Helminthosporium gramineum. The conidia (PI. 29, Aa-q) 
resemble those of H, sativum in possessing, when mature, a dark oliva¬ 
ceous color and a thick peripheral wall. An even greater degree of simi¬ 
larity to H. monoceras is manifested in the conspicuously protruding 
hilum, as well as in the attenuation of the peripheral wall in the small 
subhyaline regions at the apex and immediately adjacent to the hilum, 
from which file two polar germ tubes are destined to emerge. (PI. 
29, Ba-c.) Although most of the spores taper moderately toward the 
base, the pronounced acuminate tapering of the proximal portion charac¬ 
teristic of the spores of the parasite on barnyard grass is not frequently 
approximated. Many, although certainly not all, of the spores exhibit 
the same accentuation of basal and distal septa as H, halodes (PI. 29, Ag, 
i, o). The basal septum is more frequently found modified than the 
distal one, mainly because in the longer, rostrate individual conidia the 
distal septum apparently never differs perceptibly from the intermediate 
septa. (PI. 29, Ah, k, q.) Where a septum is conspicuously thickened, 
the delimited proximal or distal segment usually is noticeably paler in 
color, being grayish brown rather than dark olivaceous (PI. 29, Aa, g, o), 
although in other cases such differentiation is exceedingly slight or alto¬ 
gether absent (PI. 29, Ai, k, p, q). Another point of similarity to H. 
halodes is evident in the germination of immature spores, the peripheral 
wall of which has not undergone the processes of thickening and indura¬ 
tion incident to maturation, by the production of germ tubes from one 
or several intermediate segments as well as from the end segments 
(PI. 29, Bd). On artificial media the fungus produces abundant growth, 
with numerous conidiophores bearing conidia altogether similar to those 
found in nature. 
The species is readily distinguished from the other graminicolous forms 
discussed in this paper by the production of the distal portion of many of 
the conidia into a more or less attenuated apical prolongation (pi. 29, 
Ad, e, h, p, q), which in extreme cases may appear as a pronounced ros¬ 
trate termination (PI. 29, Ak, Bd). A very similar condition was illus¬ 
trated by Saccardo (126), in his figures of Helminthosporium leptosporium 
Sacc. and H, tiliae Fr. And the same author illustrated a greatly exag¬ 
gerated modification of the same type in some figures of H, hormi- 
sciodes (Corda) Sacc., a fungus which he later referred {128) to the genus 
Clasterosporium. From these three forms the fungus on Eragrostis 
major differs markedly, being considerably superior, for example, in the 
