May 26 , Z933 
Graminicolous Species of Helminthosporium 
683 
altogether smooth, a detail in which the species shows more similarity 
to H, siccans and H, gramineum than to the barley net-blotch fungus. 
No tendency toward the production of secondary spores, such as is 
manifested in H. gramineum and H, catenarium^ has ever been observed. 
As in H. catenariumy however, the distal portion of the spore is frequently 
produced into a somewhat constricted apical prolongation. Apparently 
such modification is the result of development taking place subsequent 
to the proliferation of the spore in its original condition, and thus, in 
a sense, is of secondary origin. In any case, the apical extension is 
characterized by a conspicuous paucity of septa, such cross walls as 
are found present usually appearing to have developed tardily, as the 
delimited segments frequently have not contracted away from one 
another along the edge of the plane of contact. 
In pure culture on artificial substrata the fungus produces abundant, 
although not especially characteristic, growth. Normal sporulation on 
the media ordinarily employed in laboratories has not been observed, 
although on tap water agar a relatively sparse production of somewhat 
small, atypical fructifications was brought about. The imbedded 
mycelium shows abundant anastomosis resulting in numerous com¬ 
plexes of inflated cells similar to those produced, for example, by Heh 
minthosporium teres^ H. bromic and H. tritici-repentis; and, if the analogy 
is not misleading, pointing toward the existence of an ascigerous stage. 
The fungus appears to be quite distinct from any graminicolous species 
of Helminthosporium hitherto described; as well as from several un¬ 
described forms which the writer has collected on both wild and cul¬ 
tivated members of the genus Agrostis. Because of the somewhat 
attenuated distal prolongation characteristic of many of the spores, the 
specific name stenacrum is suggested. 
DIAGNOSIS 
Helminthosporium stenacrum, n. sp. 
Occurring on withered leaves of Agrostis stolonifera I/. 
Sporophores dark olivaceous, emerging singly or in pairs, usually between adjacent 
epidermal cells; measuring 7 to 10 11 in diameter, and 80 to 250 g. in length; 3- to 10- 
septate, the septa occurring at intervals of 10 to 35 ai; producing the first spore usually 
80 to 150 At from the base, the points of attachment of successive spores occurring at 
well-defined geniculations. 
Spores subhyaline to yellowish when fully mature; 15 to 23 by 53 to 135 /x; sub- 
cylindrical with hemispherical or hemi-ellipsoidal ends, or widest somewhat below 
the middle and tapering moderately toward the ends; the apical portion sometimes 
produced into a somewhat narrowed distal prolongation; i to ii septate, the septa 
not associated with constrictions, or marked by barely perceptible constrictions. 
The peripheral wall thin and including the dark hilum within its contour. Ger¬ 
minating by the production of germ tubes from several or from all segments, the 
intermediate segments proliferating usually not more than one tube, the end seg¬ 
ments occasionally giving rise to two or even three tubes. 
Habitat. —Collected near Stamford, Conn., and Norwalk, Conn., in September, 
October, and November, 1920. . 
HELMINTHOSPORIUM DEMATIOIDEUM BUBAK & WR6bLEWSKI 
In 1916, Bubdk and Wrdblewski {18) described as Helminthosporium 
dematioideum a fungus occurring in Galicia on the glumes and paleas of 
sweet vernal grass, Anthoxanthum odoratum T. 
Caespitulis minutis, dispersis, pulverulentis, atris. Mycelio dematioideo, repente, 
atrobrunneo. Conidiophoris cylindricis, 25-60 /z longis, 5-6 latis, subtorulosis, 
septatis, brunneis. 
Conidiis cylindraceo-oblongis, 38-42 fx longis, 9-13 /z latis, maturis 3 septatis, utrinque 
late rotundatis, flavobrunneis, crasse tunicatis, levibus. 
