110 
IOWA ACADEMY OF SCIENCES 
the whole surface of the leaf. When it occurs in the latter waj it ser- 
iously impairs the vital functions of the plant. The mycelium occurs 
mostly on the lower surface, and is inclined to be distributed in definite 
spots at least during the early stages of the disease, the young leaf fre- 
uently becoming brown on the upper surface. 
Microscopic Characters. The mycelium is abundant and persistent, 
and spreading over the surface, sends small haustoria into tne epidermal 
cells. The perithecia are usually large, from 65-100"; appendages from 
8-20, much longer than the diameter of the perithecium, usually dark 
brow'n for about half their length, dichotomously forked, the forkings, 
however, not always evident; ascus elliptical or orbicular from 50-60", 
thick walled and containing usually eight spores. 
Injury. This species was found to be especially troublesome to 
Prunus demissa sometimes injuring the leaves of large numbers of plants^ 
It is also found in nearly all orchards, occasionally upon the seedlingi of 
Prunus domestica. The writer found it abundant in and about Colorado 
Springs^ It is also recorded by Nelson" as common in Wyoming and 
AndersoiT in Montana. 
Phyllactinia suffulta, (Reb.) Sacc. 
Historical. This species was described by Rebent^ as Sclerotium suf- 
fultum, but DeCandolle referred it to the genus Erisyphe using the specific 
name coryli; suffulta was restored to the species bj^ Saccardo^ 
It is not necessary in this connection to expand greatly on this species 
because it is not common so far as the writer’s observations extend, in the 
Rocky Mountains, although it is recorded by Anderson®. 
General Characters. The fungus occurs mostly on the lower surface 
of the leaf with a mycelium which is occasionally abundant and persist- 
ent or in some cases thin and evanescent. 
Microscopic Characters. The perithecia are large, from 150 to 275", 
with obscure reticulations; appendages few, usually large and rigid with 
a colorless base; asci from 4-20 or more, ovate and pedicellate; ascospores 
2, occasionally 4. 
UNCINULA, Lev. 
This genus was established by Leveilleh It contains comparatively 
few species, but some of importance as producing destructive diseases 
especially of our forest trees. They are as follows: U. clintonii, Peck, 
upon the basswood, Tilia americana; U. flexuosa. Peck, on several species 
of Aesculus; U. circinata C. & P. upon various species of Acer; U..aceris 
(Dc.) Sacc., upon some California species of maple; U. macrospora Peck, 
upon several species of Ulmus and Ostrya; V, parvula C. & P., upon 
Geltis occidentalis, the latter occurring according to Seymour from the 
1. See H. H. Hume. Proc. D'avenport Acad. 7 : 254, Contr. I. S. C. 15 : 
2. The Cryptogams of Wyoming. Kept. Agrl. Coll. Univ. Wyo. & Wyo. Agri. 
Ifixp. Sta. 10 : 20. 
3. Jour. Myc. 5 : 193. 
4. FI. Neom. 360. See also Leveille Phyllactinia guttata Ann. d. Sci. Nat. 
HI. 15: 144. PI. 7. f. 11. 
5. Michelia. 2: 50. 
6. Jour. Myc. 5 : 193. 
7. Ann. Sci. Nat. 111. 15: 151. 1851. 
