May 26, 1923 
Graminicolous Species of Helminthosporium 
653 
these tend to remain wedged in the sheath, from which, indeed, they may 
fail to become completely liberated. * The condition thus brought about 
is in a measure characteristic of the disease, although Hegyi (57) reports 
a similar type of malformation due to the attack of aphids and to a 
period of cold weather at a critical time just before heading. In a 
relatively small proportion of plants, the inflorescence emerges from the 
sheaths, but for a smaller distance than in normal plants. However, 
even then the ovaries rarely develop anything beyond abortive seeds, 
the enveloping lemmas and paleas showing a decided brownish tinge. 
Viable seed certainly is not generally produced, the few instances recorded 
by Ravn being apparently more or less exceptional. 
In southern Wisconsin, the life of diseased plants usually comes to an 
end between June 20 and June 25, depending to a large extent on the 
earliness or lateness of the season. Altibough at first readily distinguish¬ 
able in the field, the dead plants are soon hidden as a result of the con¬ 
tinued growth of the healthy individuals. By harvesting time, ordi¬ 
narily soon after the middle of July, they have usually collapsed to such 
an extent that their remains are not found without special search. 
Owing to the production of immense numbers of fructifications during 
the several intervening weeks, particularly on the dead foliar parts, the 
spores of the fungus may be distributed to the floral parts of healthy 
plants. The experimental work of Ravn showed that the reappearance 
of the disease in successive seasons is due to the resultant contamination 
or infection of the seed with spores of the fungus. When seed thus 
naturally inoculated germinates, the seedling tissues are immediately 
infected. As the gro^^ of the fungus keeps pace with that of the host, 
the parasite maintains itself in the growing point and, indeed, in all 
parts of the plant, even when at the time no outward symptoms are 
visible. The development of the disease, including its eventual mani¬ 
festation toward flowering time, thus presents a striking analogy to that 
of the systemic smut diseases, and is brought about by a similar mode 
of parasitism of the fungus concerned. To this manner of development 
also must be attributed the fact observed by von Post (ru), ^.ostrup 
{124)^ Pammel (102), Ravn (/J5), and others that the affected single 
individual plants or affected stools are quite uniformly diseased in all 
their parts, and are, with possible rare exceptions, totally destroyed. 
The use of terms like “moderate/' “slight,” “more or less,” while not 
inappropriate in describing the extent to which a barley crop may be 
affected by stripe, is altogether inapplicable in describing the severity 
of attack of individual plants, and can in such connection be interpreted 
only as evidence indicating an erroneous diagnosis. 
While in morphology Helminthosporium gramineum exhibits no striking 
characteristics, the writer is of the impression that its similarity to 
other congeneric species, particularly to those occurring on the same 
host, as well as on other cereals, seems to have been somewhat exag¬ 
gerated. It is certainly conspicuously different from H, sativum, and 
is usually not so difficult to distinguish by microscopical examination of 
its fructifications from H. teres and H. avenae as Ravn's statements 
might lead one to believe. The sporophores occur usually in clusters 
of 2 to 6, fascicles of 3 to 5 being common (PI. i, Ea-Ee), whereas the 
corresponding clusters of H, teres (PI. 2, Ea-Ec) and H, avenae (PI. 4, 
De-Dg) rarely include a larger number than 3. Although, just as in the 
latter two species, the basal segment is considerably distended, the 
width of the sporophores of H. gramineum is perceptibly smaller in the 
