May a6 ,1923 
Graminicolous Species of Helminthosporium 
. 671 
portion of the terminal segment, giving the spore a general contour crudely 
suggesting that of a rifle cartridge with contracted tip. (PI. 7, Be, f.) 
It thus will be seen that while the smaller spores resemble those of H, 
dictyoidesy and in a measure those of H, gramineum, the larger ones are 
of a length not attained by the spores of any of these species, approxi¬ 
mating most closely that of the spores of H. tritici-repentis. (PI. 7, Bb.) 
The spores of the parasites on C. arundinacea and on Agropyron repens, 
moreover, show additional similarity in respect to coloration and general 
shape, both being subhyaline, as well as more or less irregularly curved 
and of variable width. The spores of H. tritici-repentis, however, have 
not been observed to show an apical hilum or apical attenuated prolonga¬ 
tion; nor has the fungus on wood reed grass exhibited the peculiar 
modification of the basal segment characteristic of H, tritici^repentis. 
In pure culture, on potato agar or com-meal agar, the parasite on 
Cinna arundinacea grows readily, producing a white mycelium, both in 
the form of erect compact tufts 2 to 5 mm. in height and usually developed 
at the point of inoculation, or of minute superficial flecks scattered 
sparsely over the surface. In any case, the hyphae usually remain sterile 
for a number of days before the spores begin to develop terminally. 
After this stage is reached the sporophore, instead of developing by 
alternately elongating and proliferating spores, as is usual in the genus, 
usually develops in the manner somewhat similar to that characteristic 
of members of the genus Altemaria. The tip of the primary spore (PI. 
7, Dba) may bud to produce a sessile secondary spore (PI. 7, Dbc) and 
this may produce a tertiary spore in the same way. Not infrequently, 
however, the tip of the spore (PI. 7, Dbc) grows out into attenuated 
segments (PI. 7, Dae) having approximately the diameter of the primary 
sporophore and obviously of a similar nature. These segments usually 
never attain any great length before proliferating a terminal spore 
(PI. 7, Dbf); and as growth continues, fructifications result, consisting 
of superimposed spores and sporophoric segments, that may exceed 0.5 
mm. in height. As the basal and distal segments of the spores not 
infrequently produce short sporophoric branches directed at oblique 
angles to the main axis (PI. 7, Dab, ac, ad, af) and bearing one or more 
spores (PI. 7, Dbd, be, bg), the fructifications usually are further com¬ 
plicated by the presence of a number of lateral sporiferous processes. 
It may be mentioned in this connection that the distinction between 
spore segment and sporophoric segment is not always well defined, but 
often may be partly obliterated, the fructification then being represented 
by a process of segments varying from 6 to 18 jw in thickness, and dis¬ 
articulating at certain constricted septa marked by the presence of hila. 
As far as the writer is aware, the parasite on Cinna arundinacea has 
not been described in literature. Atkinson (4), it is true, reported 
Helminthosporium turcicum as occurring on the leaves of this host in 
Alabama. While it is not impossible that Atkinson may have been 
dealing with the same fungus that causes injury to maize, there would 
seem to be much more probability in the assumption that this writer 
was confronted with the fungus under consideration, although with the 
exception of the pathological effects occasioned by them, the similarity 
between the two parasites can hardly be said to be a close one. Because 
of its tendency toward the formation of chains of spores in nature as 
well as in pure culture, the fungus on wood reed grass is named H, 
catenarium. 
