514 Lueders—Vegetation of the Toivn Prairie du Sac. 
ner where some bluffs reach a height of three hundred and fifty 
feet above the surrounding country. 
The foot of these bluffs is well protected by detritus and 
supports a mixed growth of trees and a few characteristic 
shrubs and herbaceous plants as: Staphylea trifolia, Arabis 
Canadensis, Astragalus Canadensis, Polypodium vulgare and 
Camptosorus rhizophyllus. The sides of the bluffs are fre¬ 
quently too steep for larger vegetation; but we notice Pellaea 
gracilis, P. atropurpurea, Cheilanthes lanuginosa, Woodsia 
Ilvensis, Sullivantia Ohionis, Aconitum uncinatum; and on the 
brow of the bluffs, Symphoricarpus racemosus, Juniperus Vir- 
ginianus, J. communis, Opuntia Rafinesquii, and Zygadenus 
elegans. 
We have now mounted four successive terrace-steps and found 
on each some vegetative forms that reached there a fuller de¬ 
velopment than at other levels and we have in this way covered 
the greater part of the surface of the town. Two groups have 
however escaped our notice. The greater part of the course of the 
Wisconsin river and parts of Honey and Otter creek are fringed 
by a narrow belt of alluvial sand with hardly any organic or 
other material to hold the sand together. Its vegetation is 
therefore wholly dependent upon the streams for moisture and 
nourishment. Out of similar material the Wisconsin builds its 
islands that wax and wane at every freshet. The flora of this 
alluvial sand is not a large one, and is very homegeneous. 
Vilfa cryptandra, Spartina cynosuroides, Salix longifolia, Betula 
nigra, Fraxinus Americana, Acer dasycarpum, Thalictrum pur- 
purascens, and Ranunculus abortivus, are its most prominent 
species. 
Another quite distinct group of vegetation is represented by 
an area of about 40 acres in the centre of section 7. The tam¬ 
arack swamp, with its characteristic Larix Americana, Cypri- 
pedium spectabile, Betula pumila, Rhamnus alnifolius, Trien- 
talis Americana, Cornus Canadensis, and Rhus venenata, has 
here its typical representation. 
With this I close my hasty survey of the vegetation of that 
region. We see that the surface of the town is mostly dis¬ 
posed in a series of steps differing from one another in charac- 
