136 Rhodora [Jurv 
A New VARIETY OF SALIX DISCOLOR FROM SOUTH DAKOTA. 
At the junctureof Minnesota, South Dakota, and North Dakota is a 
district very interesting geologically and botanically. It was once the 
scene of great glacial activity. In general, it lies between the Dakota 
and Minnesota lobes of the Wisconsin glaciation. 
Topographically this district may be separated into 3 fairly dis- 
tinct parts, namely, (1) the trough, occupied by Big Stone and Tra- 
verse Lakes, which lies on the boundary line between Minnesota and 
the Dakotas, at an elevation of about 1,000 feet above sea level; (2) 
the gently sloping plain which lies directly west of the trough and 
reaches an elevation of 1200 to 1300 feet on its western edge, and (3) 
the rough and dissected morainal hills which extend north and south, 
forming the western boundary of the plain some 10-15 miles west 
of the lakes, and extending a little way into North Dakota. These 
hills, known as the Sisseton Hills, probably reach an elevation of 
nearly or quite 2,000 feet at the highest points. Beyond these hills, 
the higher plains stretch away to the westward. 
This district is made interesting also by another topographic fact. 
Big Stone and Traverse Lakes lie end to end in a curved glacial valley. 
They are separated only by a low ridge or moraine a few miles wide 
lying transversely across the valley floor. In spite of this proximity 
and slight separation, however, they belong to entirely different 
drainage systems. 
Big Stone Lake drains through the Minnesota River to the Missis- 
sippi and thence to the Gulf of Mexico and the Atlantic. Traverse 
Lake is drained by the Red River of the North to Lake Winnipeg 
and thence to the Arctic. 
From these facts it follows that these lakes lie on the “Height 
of Land” of the old geographies, which separates the Arctic and 
Mississippi drainage basins. Furthermore, they are about 300 miles 
south of the Canadian line. As the Missouri River enters North 
Dakota far to the northwest and not far from the Canadian line, and 
as the Mississippi River rises far to the northeast in Minnesota it 
is seen that Traverse Lake occupies the southern apex of a triangle 
of Arctic drainage projecting far south into Mississippi Basin drainage. 
The Red River has its source in Traverse Lake but the Minnesota 
River does not rise in Big Stone Lake. Its sources are 10 to 15 miles 
northwestward in the Sisseton Hills, previously described. The 
abrupt eastern face of this low range is cut by numerous deep, 
