WHITE-PINE BLISTER RUST. 53 
Grossularioides. — Ribes lacustre: Dead spots formed early on infected leaves; 
sori sparse or diffuse, irregular spots; telia rather scattered. 
Grossularia. — Ribes lobbii: Sori thickly crowded on rounded spots, telia well de- 
veloped. 
Ribes menziesii: Sori sparse on small irregular spots. 
Ribes speciosum: Sori seated closely together on large rounded spots, telia 
rather short. 
EuGROSsiLARiA. — Ribes alpestre: Sori thickly crowded on large rounded spots, 
telia short. 
Ribes curvatum: Sori crowded on rounded spots on young leaves, on irregular 
spots on old leaves; telia quite plentiful; spots with reddened edges late in 
season. 
Ribes cynosbati: Sori plentiful on definite spots, which are usually rounded 
(PI. V, fig. 1); spots sometimes wedge shaped, lying between two branching 
veins of the leaf; telia crowded in small groups, 1 to 1| mm. long, rarely over 
entire leaf surface. 
Ribes divaricatum: Sori scattered on rounded spots. 
Ribes missouriense: Sori crowded on rounded indefinite spots on young leaves, 
densely crowded on small leaves, dead irregular spots on old leaves. 
Ribes leptanthum: Sori very scant; dead spots appear so early that uredinia 
can form with difficulty, often only one uredinium on a spot, many spots with- 
out sori; produces the least sori of any species ye t t noted. 
Ribes hirtellum: Sori usually crowded thickly on small spots; uredinia on 
small rounded spots; telia small, crowded densely; on older leaves, on small 
indefinite, irregular spots bounded by veinlets; spots sometimes purplish on 
the edges. 
Ribes oxyacanthoides: Like R. hirtellum. 
Ribes reclinatum: Sori rather sparse, on small irregular spots of dead tissue. 
There is a tendency toward a reddening or purpling of the edges of the spots 
on old leaves. (PI. V, fig. 3.) 
Ribes rotundifolium: Sori crowded on small irregular spots. The spots die 
early and are likely to become reddish around the edges even on rather young 
leaves. It is rather rare for the entire leaf to become covered with sori. 
Ribes setosum: Much like R. cynosbati. 
Hemibotrya. — Ribes fasciculatum vars. chinense and japonicum: Sori densely 
crowded on large rounded spots. 
Diacantha. — Ribes diacantha: Sori on rounded spQts. 
Ribes giraldii: Sori scattered on rounded spots. 
In general, it may be said that R. nigrum and its varieties is the 
optimum host species among the Ribes for Cronartium ribicola. 
Ribes aureum and R. odoratum and their varieties are perhaps next 
to R. nigrum in favoring the growth of the fungus. R. reclinatum 
does not take the disease readily, but is by no means immune to it. 
In fact, no species or variety yet fully tested is entirely immune. 
R. leptanthum probably produces fewer sori for the extent of infection 
than any other species. This is caused by the very early death of 
the infected tissue. 
PALE COLOR OP INFECTED SPOTS ON THE LOWER SURFACE OF RIBES LEAVES. 
The production of sori on an infected spot on the lower surface of 
Ribes leaves is often preceded for one, two, or three days by a pale 
