No. 33.] 385 
years, in order that any mycelium or spores. of the disease, which 
it may have previously contained, will first become thoroughly 
exhausted and dead. 
Rusr on Canapa Tuiste. 
Puceinia suaveolens, Pers. 
There are a few instances in which fungi are beneficial by preying 
upon noxious plants, and doubtless no more conspicuous example 
can be given than that of the Canada thistle rust. 
This fungus is an endophytic -form, pervading the whole plant, 
and producing its spores on the under surface of the leaves chiefly. 
It is such a voracious feeder that the thistle is much weakened by it, 
the leaves being smaller and paler, and the flowers rarely opening, 
and never setting seed. The fungus may be known by the brown 
spores which thickly clothe the under surface of the leaves, and 
which can be partially jarred off as a brown powder. 
A thistle infested with rust should be allowed to stand, in 
order that it may produce as many spores as possible to spread the 
disease to other plants. No harm, but only good, can thus result, 
because this form of rust lives upon no other plant, whatever, but 
the Canada thistle. It will probably never exterminate the thistle, 
but it. will aid in: keeping it in check, and should be encouraged. 
REPORT OF THE ASSISTANT. 
A Classification of Barley and Oats. 
Famity. The barleys and oats are, botanically speaking, grasses, 
and belong to the Graminesx or Grass Family. This family is di- 
vided up into many tribes, sub-tribes and genera, of which the barleys 
and oats each compose a genus. The flowers are hermaphrodite, 
that is the male and female parts are located in the same flower, and 
are borne in the spikelets of the head or panicle. The two lowest 
scales of the spikelet have no flower, but instead act as envelopes 
for the whole spikelet ; these are called empty glumes. The flowers 
of oats and barley are inclosed within two scales, one above and one 
below, and the latter, which surrounds the flower and often produces 
an awn, is termed the flowering glume; the upper scale is called the 
palet or pale. The palet has no midrib, but two lateral nerves in- 
stead, which causes the tip to be slightly divided. The number of 
[Assem. Doc. No. 33.] 49 
