38 Bulletin of Wisconsln Natural History Society. Vol. 1, No. 1. 
referred to in the preceding paragraph. Many are surrounded by 
woodland of greater or less density, in other cases they lie in the 
midst of open fields or pastures. They are all characterized by 
the fact that open water stands in them during the spring and 
early summer, but disappears almost entirely after the middle of 
July. The duration of the open water period depends very large- 
ly on the amount of precipitation during the summer months. 
The soil is a black, deep muck, sometimes peaty. As soon as the 
water has disappeared, it covers itself with a rank, herbaceous 
vegetation, in which many species of Cypcraccac, especially Carcx, 
are prevalent, but a large number of other flowering plants are 
likewise found. This herbaceous vegetation covers every -inch of 
ground not occupied by woody plants, among which the willows 
are often dominant. 
The various localities of this kind differ somewhat in floristic 
detail, but the swamp found on section 34, in the large wood just 
west of the Soldiers' Home and north of the railway track, is per- 
haps the most characteristic, and has been least disturbed by hu- 
man action. This swamp is surrounded by vigorous hardwood 
forest, very mixed in species, but with Acer barbatnni and Qiierciis 
alba strongly predominating. Along the edge of the swamp are 
many vigorous trees of Fraxinus sainbiicifolia, together with a 
few young specimens of Acer rnbruin, a rare tree in this neigh- 
borhood. About two-thirds of the surface of swamp itself is 
covered with shrubs. The majority of these belong to the several 
species of Salix enumerated below. Besides these, there occur 
Cornus stolonifera. Vibiirniini acerifoliuin, V. 0 pubis. Spiraea 
salicifolia, and perhaps others. The number of shrubs of the 
genus Salix and the other species is about as three to one. Among 
Salix, again, Salix aiiiygdaloides is far more frequent than any of 
the others. (4) 
The habitus of the willows found in localities such as these is 
strikingly different from those along the rivers. In the willow 
thickets described above, the roots of the trees and shrubs can 
rarely be seen. In these swamps, however, stout, horizontal roots 
invariably lie on the surface of the soil The same peculiarity is 
noticeable with other trees and shrubs grown in very wet places. 
But still more striking is the prevailing narrowness of the leaves 
in S. ainygdaloides; they often approach almost the dimensions of 
5^. Hm'iatilis. The other species do not seem to be affected that 
way. It will be interesting to observe the difference in conditions 
4. In September. 1899, the leaves of S. amv^daloides in this swamp were al- 
most entirely covered with some mildew, probably Uncinula Salicis Winter. The 
other species seem to be immune. But the entire thicket, from a distance, looked as 
if white-washed in consequence; which shows how much S. amvgdaloides predom- 
inates. 
