30 SUGGESTIONS ON THE COLLECTING AND STUDY
right, or our own "Microscopic Fungi," where he will see the names
of the plants on which he is likely to find some species of AEcidium.
Putting the knowledge so acquired to use, he will go in search of
the plants indicated, and when found will hunt up the fungus.
Later in the season the pilewort will be sought again, but this
time for the sake of purplish-black blotches on the leaves, but defi-
cient of any cups. This is quite another kind of fungus, and the
spores may be submitted to the microscope, in a drop of water,
under a quarter-inch objective. Each spore has a short uncoloured
stem, and is somewhat globose, consisting of a single cell. A little
experience will be necessary to distinguish the spores of Uredo
from Uromyces, but this will be Uromyces. Both Uromyces and
Puccinia have a Uredo form, and were formerly called Uredo, and
believed to belong to different species, instead of conditions of the
same species. In Uromyces the peduncle or stem is persistent,
whereas in Uredo it is deciduous. In many species of Uromyces the
coating of the spore is thickened at the apex, whereas in Uredo it is
of equal thickness throughout. The species of Uromyces are fond
of the pea family. They are found on peas, beans, vetches, clover,
laburnum, &c., and upon plants of other orders. The clusters of
spores usually are darker in colour than those of Uredo.
Examples of Uredo may be seen on the leaves of docks, dande-
lion, and other Composites, and as the red rust of wheat and grasses.
In passing, it may be remarked that the parasite is most com-
monly developed on the under sides of the leaves, although some-
times upon both. In many cases seedlings are more subject to
attack than full-grown plants. These, however, are generalisations
to which there may be many exceptions.
In past times minute distinctions were taken advantage of to
separate into different genera the species which are now usually
classed as simply Uredo. Practically, therefore, Trichobasis and
Lecythea are synonyms of Uredo.
There is one group of species which resemble Uredo in habit,
but mostly with bright yellow or orange spores which differ essenti-
ally in the spores growing attached to each other in chains. This is
Coleosporium. One species is common on the coltsfoot.
We come now to the large genus Puccinia, with the spores divided
by a septum across the middle so as to be bicellular. These are
later in the year in coming to maturity than AEcidium or Uredo.
The tufts of spores are darker, and generally more compact than in