Green-Mountain freeman. [volume] (Montpelier, Vt.) 1844-1884, 1879-05-14
LETTERS ON NATURAL HISTORY,
Cluster Cups on the Leaf.
No. 6.
by DIR. HIRAM A. CUTTING.

the atmosphere, which is as necessary 10
them as our breath is to us.
Anything that clogs or Injuries the s;o-
mata of any plant directly Injuries the
growth of that plant. This little fungi,
when the plant has become infested,
breaks through the epidermis, destroying
many of the breathing pores (stomata),
and also draws its own nourishment from
the life juices of the plant it infests. Be-
fore it breaks through the under surface of
the leaf, the infested leaf if closely ex-
amined. will appear to be covered with
little elevations or pustules, paler at the
apex; these soon become ruptured, and
the fungus pushes its head through the
opening, at the same time bursting by IA
dating assures. The teeth thus formed
resemble those of the peristome of some
moses. All around the orfice the teeth,
or fringe. becomes recurved, and the
orange spores, (fungi seed), are exposed,
crowded together within. At first, and in
fact while contained in the perdium (cup),
these spores are connected together rs n
string Of beads, but when dispersed they
are scattered singly about the orifice,
often mixed with colorless cells arising
from the partial breaking up Of the teeth,
or fringe, of the peridium, Let us now
for moment examine the manner in
which these cups are distributed upon the
leaf. They are scattered without any ap-
parent order over the under surface, with
now and then one upon the upper surface,
but they nowhere touch each other, unless
mt the margins of the leaf, but then they
are never joined, only crowded. Gener-
ally there is a space greater than the width
of the cups between them. The leaf is
not thickened by their growth, and the
upper surface gives you no indication of
what is going on beneath. If a leaf be
taken fresh and the epidermis from the
under side be stripped off, as it is often
very easy to do, the orifces through which
the fungi have burst will appear in irreg
ular holes, and the fungi will be left root
ed still upon the leaf, showing that they
are not confined to the surface, and thus
we see why the damage is so great to the
plant upon which they subsist.
The spores in this species are orange in
color, but variable both in size and form,
though the majority are comparatively
large. Each of these spores are capable
of reproducing the species, and if we COM
pute two thousand cluster cups as occur
ring on each leaf, and many leaves have
double this number, and supposing each
cup to contain two hundred and fifty
thousand spores, which again is much
below the actual number, then we shall
have not less than five hundred millions
of reproductive bodies on one infested
leaf, to furnish crop of parasites for the
plants of the succeeding year. AS we
thus so soon reckon by millions, our figures
and capacities fail in approaching the
myriads of spores which compose the
orange dust produced from one infected
cluster of plants. Nor is this ALL for it is
found that one of these spores is not only
capable of producing plant, but is in
itselfa bundle of vegetative spores, which
are exceedingly minute, and yet small as
they are, they have the capability to pro-
duce fresh crops Of cluster cups.
Naturally enough, our reader will ere
this be debating in his own mind how
these spores, which we have seen are shed
in such profusion, can enter the tissues OF
the plants which give subsequent evidence
of infection, rs have described. In fact,
how the yellow dust with which the at
mosphere may be filled to day can inocu-
late the young plants of next year. If one
or two of these spores are sprinkled upon
the cuticc which has been removed from
the leaf, rs we have before indicated, il
will be seen that they arc very mucl
larger than the stomata, or breathing
pores, which stud the cuticle; hence il is
clear they cannot gain admittance there
There remains but one other portal to the
interior of the plant, and that is through
the extremities of the roots Here another
difficulty arises; for the spores are as
large rs the cells through which they
would there have to pass. This difficulty
is however much lessened when we re
member that these spores are IL bundle oI
infinite particles, each particle of which i:
probably capable of infesting plant
Even under this consideration there il
much need of an active Imagination, t,
invent hypotheses, to cover the points upor
which we as yet know nothing definite.
The Rev. NJ. j. Berkeley proved man!
years ago that the spores of bunt, for ex
ample, may be caused to infect all TIN
plants the seeds Of which had been placed
in contact with them" But this did no
prove that the seeds absorbed them, as
is probable they did not, but they woul'
adhere to the seed and thus be conveyed t,
the ground, where infection to the sprou
would be probable. Much has been don
to elucidate this mystery. but much re
mains mystery still. No spores hav
ever been seen traversing the tissues o
growing plants.
The stems and leaves of violets, sweet
scented and scenlless all alike, are ofto
distorted AMI ruined altogether by vari
ETY. of cluster cups; tine singing nettl
does not escape; the hardy dock, the use
full currant, the wild geraniums, alik
feed with their juices fungi of this de
scription.