MILDEWS, RUSTS AND SMUTS 43 
a few may be quite simple ; asci 4— 12 ; spores usually 
8, 22—26 X 13—^15 
Syn. Uncinula hicornis, Lev. 
Readily distinguished from all other species by the forked 
appendages. 
Parasitic on the leaves of the sycamore (Acer pseudo- 
platanus), Acer campestre, and other species of Acer. 
Uncinula salicis, Winter. Mycelium usually soon dis¬ 
appearing, sometimes forming white persistent patches ; 
perithecia usually much crowded, sometimes scattered, 
averaging 135 p diam., appendages usually crowded, 100— 
150, sometimes fewer, simple and curled at the tip ; asci 
variable in number, 4—14; spores 4—6, 20—26 X 10—15 p. 
Syn. Erysiphe adunca, Link. 
Uncinula adunca, Lev. 
A variable species as regards the size of the perithe- 
cium, but distinguished by the numerous, simple appendages 
which are not much longer than the diameter of the peri- 
thecium. 
Parasitic on the leaves of various species of poplar, as 
Populus halsamifera, P. alba, P. tremula, etc., also on species 
of willow, as Salix aurita, S. capraea, S. nigra, S. cinerea, 
etc. 
Uncinula prunastri, Sacc. Mycelium soon disappearing ; 
perithecia gregarious or scattered, variable in size ; appen¬ 
dages very variable in number, 12—60, becoming enlarged 
towards the curled tip, simple ; asci 7—18 ; spores 5—7, 
i6-—20 X 8—10 p. 
Syn. Uncinula wallrothii. Lev. 
A variable species as regards the size of the perithecium. 
and the number of appendages. Some forms approach^ 
U. clandeitina, which differs in the ascus containing only 
2—3 spores. 
Parasitic on the leaves of species of Prunus. 
Uncinula clandestina, Schroet. Mycelium usually soon 
disappearing, or persisting as a very thin, white him; 
perithecia crowded in small patches, or scattered, 85—^115 
p, diam. ; appendages few, 9—30, usually about 15, simple, 
usually rough near the base, becoming swollen at the 
curled tip ; asci 3—5, usually 4 ; spores 2, or rarely 3, 
30—34 X 15—18 p. 
Syn. Uncinula hivonae. Lev. 
Parasitic on the leaves of species of elm (Ulmus campes- 
