mon trees from a
_Capnodium_, which covers the foliage as if with a coating of soot. In
fact most useful plants appear to have some enemy to contend with, and
it is fortunate, not only for the plant, but its cultivators, if this
enemy is less exacting than is the case with the potato, the vine, and
the hop.

Forestry in Britain is an insignificant interest compared to what
it is in some parts of Europe, in the United States, and in our
Indian possessions. In these latter places it becomes a matter of
importance to inquire what influence fungi exert on forest trees.
It may, however, be predicated that the injury caused by fungi is far
outstripped by insects, and that there are not many fungi which
become pests in such situations. Coniferous trees may be infested
with the species of _Peridermium_, which are undoubtedly injurious,
_Peridermium elatinum_, Lk., distorting and disfiguring the silver
fir, as _Peridermium Thomsoni_, B.,[j] does those of _Abies
Smithiana_ in the Himalayas. This species occurred at an elevation of
8,000 feet. The leaves become reduced in length one-half, curved,
and sprinkled, sometimes in double rows, with the large sori of
this species, which gives the tree a strange appearance, and at
length proves fatal, from the immense diversion of nutriment requisite
to support a parasite so large and multitudinous. The dried specimens
have a sweet scent resembling violets. In Northern Europe _Caeoma
pinitorquum_, D. By., seems to be plentiful and destructive. All
species of juniper, both in Europe and the United States, are
liable to be attacked and distorted by species of _Podisoma_[k] and
_Gymnosporangium_. _Antennaria pinophila_, Fr., is undoubtedly
injurious, as also are other species of _Antennaria_, which probably
attain their more complete development in _Capnodium_, of which
_Capnodium Citri_ is troublesome to orange-trees in the south of
Europe, and other species to other trees. How far birch-trees are
injured by _Dothidea betulina_, Fr., or _Melampsora betulina_, Lev.,
or poplars and aspens by _Melampsora populina_, Lev., and _Melampsora
tremulae_, Lev., we cannot say. The species of _Lecythea_ found on
willow leaves have decidedly a prejudicial effect on the growth of
the affected plant.

Floriculture has to contend with many fungoid enemies, which sometimes
commit great ravages amongst the choicest flowers. Roses have to
contend against the two forms of _Phragmidium mucronatum_ as well as