1890.] 
157 
[Upham. 
spread the entire Red river basin, advancing with the increase of 
settlement and the subjection of the whole country to tillage ; and 
many new species of weeds also, according to experience elsewhere, 
will inevitably come in. 
The agriculture of onr Atlantic slope was necessarily preceded 
by the clearing away of portions of the primeval forest ; for no 
naturally prairie district existed there. Few of the indigenous 
plants of that area were fitted by their inherited tendencies to sur- 
vive and thrive in the open land and cultivated fields, which were 
therefore chiefly supplied with their weeds by unintentional impor- 
tation from Europe, as in grain, grass seed, and in the many almost 
mysterious ways by which they always accompany the farmer colo- 
nist. But in the great campestrian region of the West some of the 
native species, long accustomed to open and unshaded land, find 
still more favorable conditions for rank growth and rapid extension 
of their geographic limits when the soil is broken by the plow and 
sown and planted with crops. Hence it will be desirable, in the 
following annoted list of the most plentiful weeds of this basin, to 
distinguish the naturalized species, which is done by printing their 
names in Italic type. 
PRINCIPAL WEEDS, INDIGENOUS AND NATURALIZED, IN THE BASIN 
OF THE RED RIVER. 
Ranunculus acris , L. ( Tall Buttercups ) , infrequent, yet observed 
at many places, in Minnesota ; reported by Macoun as becoming 
common in eastern Manitoba. 
Arabis lyrata, L. (Rock Cress), occasionally plentiful on dry 
fallow land near Brandon, Manitoba. 
Draba nemorosa, L., var. leiocarpa, Lindb., plentiful in a fallow 
field on the bluff at the Elbow of the Souris river, Manitoba. 
Camelina sativa, Crantz ( False Flax), becoming frequent in cul- 
tivated fields, and along railways, in Minnesota, North Dakota, 
and Manitoba. 
Barbarea vulgaris, R. Br. (Winter Cress, Yellow Rocket), some- 
times a weed in grain-fields, North Dakota, apparently the var. ar- 
cuata, Koch, which is found there indigenous in dried sloughs. 
Erysimum cheiranthoides, L. (Wormseed Mustard), a frequent 
weed in gardens and cultivated fields. 
Erysimum parviflorum, Nutt. (Small-flowered Prairie Rocket), 
