Download the full PDF (13Mb)

EUSTS. 103
of mint, especially tiie
of August. We have found a few of the two-celled
watermint_, about the month
spores of the Puccinia imbedded in the pustules of
this rust almost constantly, whilst the one-celled
spores are not uncommon in the pustules of what
is regarded as the true mint brand {Puccinia Menthee.,
P.).
In spring the young leaves of the periwinkle
{Vinca major) will, in some situations, become
thickened considerably, and ultimately browned on
both faces with the pustules of a rust (Trichohasis
Vincce), which though covered with a conidioid dust
are often very tardy in bursting the epidermis. It
is almost impossible, after the pustule is ruptured,
to find one in which the bilocular spores of Puccinia
(fig. 132) are not largely intermingled with the
unilocular spores of the ^^rust'^ (plate YI. fig. 131).
Later in the season by two or three months, other
leaves of the same plants will be found occupied
by the smaller and more widely scattered pustules
of Puccinia Vincce, in which the unilocular spores of
the ^^rust ^' will seldom be found. In this instance
the leaves are scarcely thickened, and the colour of
the spores is much darker. The under surface of
the leaves is
commonly alone occupied, and corresponding
paler spots on the upper surface indicate
the presence of the parasite beneath.
The garden and field bean is Hable in some seasons
to become quite rust-coloured in consequence
of the profusion of spores with which the leaves