Download the full PDF (13Mb)

62 MICROSCOPIC FUNGI.
the same species
: tlie latter we liave foimd in tlie
montli of May, and the former in August and
September. The lower leaves of young seedlings
have generally rewarded us with the best
specimens of the septate-fruited brand {Puccinia
variahlUs, Grev.). The pustules occur on both
sides of the leaf, and are
very small and scattered
(fig. 82). The spores are singularly variable in
form : sometimes both divisions are nearly equal
in size ; sometimes the upper,, and sometimes th&
lower^ division is the smallest; occasionally the
septum will be absent altogether;
and more rarely,
the spores will contain three cells. From the very
variable character of the spores (fig. 83), th&
specific name has been derived.
No species in the entire genus makes so prominent
an appearance as the one found on the radical
leaves of the spear thistle {Carduus lanceolatus)
,
This latter plant is exceedingly abundant, and so
is- its parasite [Puccinia syngenesiarumj Lk.). From
the month of July
till the frosts set in we may be
almost certain of finding specimens in any wood.
The leaves have a paler roundish spot, from onetwelfth
to one-fourth of an inch in diameter, on the
upper surface, and a corresponding dark brown
raised spot on the under surface, caused by an
aggregation of pustules, forming a large compound
pustule, often partly covered with the epidermis.
The individual pustules are small, but this aggregate
mode of growth gives the
clusters great pro-