6 
MILDEWS, RUSTS AND SMUTS 
SCLEROSPORA 
Agreeing with Bastdiophora in the oosphere being pro¬ 
vided with a very thick wall, but distinguished by the stout, 
short conidiophores bearing several stout branches near 
the tip, from which the conidia originate. 
5. graminis has been recorded as proving destructive 
to Indian corn, attacking the inflorescence and seed. 
PLASMOPARA 
Forming more or less effused, delicate white patches, 
generally on living leaves, and mostly on the under surface ; 
the portions on the upper surface of the leaf, correspond¬ 
ing to the diseased patches on the under surface, are at 
first yellowish-green, then brown and dead. The conidio¬ 
phores are more or less branched, and are more persistent 
than in some other genera. The wall of the oosphere is 
exceptionally thick. Some are very destructive parasites 
on cultivated plants. 
BREMIA 
The single species included in this genus is readily dis¬ 
tinguished by the very remarkable structure of the tips 
of the ultimate branchlets of the conidiophores, which 
are expanded into a more or less saucer-shaped structure, 
having four or five projections situated at intervals along 
the edge, each of which bears a conidium. 
The fungus often proves very destructive to lettuce, 
especially when grown under glass, the leaves become more 
or less covered on the under surface with an exceedingly 
delicate white mould, turn yellow, and die, the whole 
plant being stunted in growth. Chicory and artichokes 
are sometimes also severely attacked, as are also cultivated 
Cinerarias. 
PERONOSPORA 
Distinguished by the structure of the conidiophores, 
which emerge through the stomata, usually in small tufts. 
There is a fairly long, unbranched stem, which near the tip 
becomes branched by repeated forking in pairs ; the upper 
branchlets are frequently curved, the ultimate ones, which 
bear the conidia, taper to a point. The conidia are blunt 
and broadly rounded at the tip. Plasmopara most nearly 
approaches the present genus, but differs in the branching 
not being regularly forked in pairs, and in the tip of the 
