4 BULLETIN 759, U. S. DEPARTMENT OF AGRICULTURE. 
exposed to the sun, or it may be more or less dendritic, with a fringe 
of olive-colored rays. No marked killing or sinking of the leaf 
tissue occurs. In size, the spot rarely exceeds 2 or 3 millimeters in 
diameter. | 
The disk at the center of the spot is the fruiting structure of 
the fungus and consists of a mass of asci which discharge large 
numbers of spores when sufficient moisture is present. These disks 
usually occur on the upper side of the leaf, sometimes on the lower 
side, and rarely on both sides from the same spot. Typically they 
are 1 to 14 millimeters in diameter, slightly raised, and when fully 
developed surrounded by the torn edges of the epidermis of the leaf. 
Rarely the central disk is found surrounded with several smaller 
disks at its margin. Under very moist conditions the disk may ap- 
pear as a jellylike drop of exudate at the center of the spot. Under 
arid conditions it becomes very dark in color, often almost black. 
There is not usually a striking difference in color between the dis- 
cased tissue and the disk at the center. This color varies from dark 
brown to almost black. If the leaf has begun to yellow, the green 
color is sometimes retained longest around the diseased area. 
The disease often occurs on succulent stems, where it has an ap- 
pearance so characteristic that it can hardly be confused with injury 
from any other cause. The spot is elliptical in shape, with perfectly 
smooth edges. In size it is about 1} by 3 mm. It is not abundant, 
and rarely bears a fruiting disk. 
DESCRIPTION OF THE DISEASE ON RED CLOVER. 
The leaf-spot on red clover caused by Pseudopeziza bears a very 
close resemblance to the similar disease on alfalfa. The spots are 
limited in size, usually slightly larger than on alfalfa, in early 
stages tending to be angular (PI. I, C). The border of the spot is 
more frequently dendritic in outhne. In early stages the color is 
dark olive, becoming brown or almost black in later stages. After 
the death of the entire leaf, the spot usually becomes almost indis- 
tinguishable. Fruiting-disks are not as frequently found abundantly 
on the spots while the leaf is still alive as in the case of the leaf-spot 
of alfalfa, but they may develop abundantly after the death of the 
leaf. In early stages they are brownish or dirty yellow, but later 
they become almost black. They are more frequently found on the 
under side of the leaf than on the upper side, and occasionally occur 
on both sides from the same spot. On dead leaves they appear as 
amber drops of jelly in wet weather, but when dried they shrink to 
bodies so small and inconspicuous that it is practically impossible 
to find them. The disease has not been noted on any other part of 
the plant than the leaves. 
