40 
IOWA ACADEMY OP SCIENCE 
Rocky Mountains and along irrigation ditches and in fields in the east- 
ern states. It rarely occurs in Iowa. The T, porrifolius also occurs 
in the Rocky Mountains. The Galinsoga (Galinsoga parviflora) of trop- 
ical America was first observed by the writer in Missouri near hotbeds 
and greenhouses in 1886. It had made its way northward to Wisconsin 
in 1903, and was observed in Iowa about the same time. It has spread 
to Utah and adjacent regions. Generally found near hot beds and 
greenhouses. 
A few weeds of the Gruciferae are widely distributed in the older 
cultivated portions of the Northwest, especially in Manitoba. The com- 
mon Mustard {Brassica arvensis) is one of the most common weeds of 
grain fields and associated with it, but somewhat more widely scat- 
tered, the Penny-cress or Stink Weed {Thlaspi arvense) should be men- 
tioned. This weed is common throughout the provinces of Saskatchewan, 
Alberta, and Manitoba, less frequent in British Columbia. It occurs 
along railways and it is abundant also in the grain fields of the Dakotas 
and Minnesota but less frequent in Iowa. Not infrequent in Utah to 
Montana and Washington. Its spread in Canada is attributed to seed 
and hay. The Black Mustard {Brassica nigra) is less frequent than 
Charlock. It is common in Iowa. The Brassica campestris is more fre- 
quent on the coast in Vancouver, Washington and Oregon. The Shep- 
herd’s Pudse {Gapsella Bursa-pastoris) is common from Winnipeg to 
the coast, south to Texas, the Rocky Mountain region and to the Atlantic 
coast. It is more abundant in the north than in Iowa because of the 
cooler climate. 
The Small Pepper Grass {Lepidiiim apetalnm) is common from Winni- 
peg to the mountains, though more frequent in Manitoba than westward. 
It, however, has spread westward through British Columbia south ti> 
Washington. It is a common weed throughout the Mississippi Valley 
from Missouri to Kansas to the Dakotas east to Wisconsin. Dr. Robinson 
says ‘‘perhaps native in the west, recently introduced eastward.” It 
is certainly the common species in the west; the larger Pepper Grass 
{L. virginicum) is common southward, rare northward and not observed 
in Canada. Of the Hedge Mustard {Sisynibrium) the latest of the 
European immigrants, the Tumbling Mustard {Sisymbrium alUssimum) 
which has had but a comparatively short history in this country, is 
frequent in many parts of Minnesota, North Dakota through Montana 
to Washington and to the south in Utah, and parts of Colorado and 
occasionally in Iowa. It is abundant in the provinces of Manitoba,- Sas- 
katchewan, Alberta, and British Columbia, occurring everywhere along 
railroads and in grain fields. The Berteroa incana is a recent introduc- 
