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112 MICROSCOPIC FUNGI.
remains of tlie ruptured epidermis. The spores are
globose and brown (plate YII. fig. 139). We have
not met with any other Uredine on the sorrel
leaves^ though one having a similar appearance
to the naked eye
is not uncommon on several
species of dock.
The fern rust {Uredo Filicmn), which occurs on
the under surface of the fronds of two or three
species of ferns^ we have never met with^ and do not
think that it can be considered common. It has
been found in the West of England, on Cystopteris,
and Sowerby collected it_, probably not very far
from London.
One of the most common is the rust found on
the leaves of the enchanter's nightshade {Circcea
lutetiana), sometimes nearly covering the under surface
with its
tawny snuff-coloured spores (plate VII.
fig. 135). The plant on which it is found is rather
local,, but the rust [Uredo Circcece) seems to abound
wherever the plant on which it is parasitic flourishes.
Another fungus of a very similar external appearance
may be collected, more rarely, from the leaves
of the same plant ;
but in this the spores are twocelled,
or divided by a transverse partition. This
fact is mentioned to guard against disappointment,
should the spores be found to differ from the
characters of this section, and to show that the
microscope is essential to the study of fungi. The
spores of the true Uredo are globose and without
any partition (plate VII. fig. 136).