THE GEOGRAPHICAL DISTRIBUTION OF NORTH DAKOTA PLANTS 237 
limits in that region; it is reported as far as Nebraska (11) and Iowa (10) 
but from Minnesota for the first time in 1901 (13) from farther north. On 
the Minnesota side near Fargo is a colony of Petasites sagittata which seems 
to be the most southeastern point known for that species. Pyrola elliptica 
and Viola conspersa are found in the same piece of aspen woods. Ilysanihes 
dubia, an austral species, has been found in quantity at Wild Rice which 
is ten miles farther south. Celtis occidentalis, which extends irregularly 
farther north, is frequent at Fargo. 
At Walhalla there is a typical butte, said by Willard (14) to be perhaps 
the easternmost in the United States. Upon this grow a number of plants 
which are otherwise found only in the western part of the state, such as 
Eriogynum flavum, Artemisia cana, and Juniperus horizontalis . In the 
woods of the river near by occur a number of woodland plants which are 
known from no other locality in the state: Mitella nuda, Rhamnus alnifolia, 
and Asarum acuminatum, which are purely eastern species; also Cardamine 
pennsylvanica, Petasites sagittata, Leptorchis Loesselii, Car ex leptalea, and 
Cinna latifolia, which also occur in western North America. 
From Sentinel Butte and Medora only, is recorded Dasiphora fruticosa. 
This is a Canadian to Arctic Zone plant of wide distribution and these 
stations are perhaps to be regarded as cut off from the Black Hills region, 
but it seems strange to find this plant where there is a prominent representa- 
tion of austral forms. Likewise, Juniperus horizontalis, which is mainly 
a Canadian Zone species, is common on the buttes and hills along the Mis- 
souri and westward. 
The distribution of the two species of lupine {Lupinus argenteus and 
L. pusillus) extends, as far as known, about to the southern limit of the 
glaciated area as indicated by Leonard (7) . 
Introduced Species 
Of the introduced species, the abundance of Brassicaceae and Cheno- 
podiaceae (including such recent introductions as Erucastrum PoUichii, 
Camelina dentata, and Axyris amaranthoides) , and the scarcity of Poly- 
gonaceae {Rumex spp. and Persicaria forms) and of Euphorbiaceae are 
noteworthy. Of Compositae, Carduus arvensis and Sonchus arvensis are 
by far the most important. 
The observations made by Upham (12) thirty years ago are interesting 
in comparison with present conditions. He notes of Thlaspi arvense: 
"long established and very abundant in the vicinity of Winnipeg, recently 
spreading into Minnesota and North Dakota." Of Taraxacum officinale: 
"frequent along roadsides, in pastures, etc., about Winnipeg and plentiful 
at the west end of the main street in St. Vincent; generally rare or absent 
throughout the Red River Valley." Both of these plants have since be- 
come particularly abundant in the valley. He also notes the absence of 
Ambrosia trifida (native weed) from the district about Langdon where it is 
