148 BULLETIX OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 2 NO. i. 
in many details, agreeably to the more xerophytic character of 
the flora. 
In many places, the forest has given way altogether to a Poa 
heath. This is probably the normal case whenever the tree cover 
is entirely removed, unless there is an opportunity for coppice 
growth. The latter is more or less of an accident, as the small 
farmers who own the land rarely regulate their cutting with th^s 
end in view. Mesophytic thickets of witch hazel and its asso- 
ciates, such as are common farther east, seem to be absent in 
Waukesha County. Even north and east exposures become Poa 
heaths with hemixerophytic shrubs, and the only difference be- 
tween them and south or west slopes seems to be, that in the latter 
the progress from heath to thicket is a little faster. 
Among the shrubs that are most conspicuous in the early 
stages of a heath are hazelnut, several species of hawthorn, and 
the staghorn sumach. Later come choke cherries, wild plums, and 
crab apple. On the Kettle Range, clumps of red cedar are a 
prominent feature of these localities. They do not seem to be 
able to thrive in thickets, however, and therefore disappear, when 
the later stages are reached. The trembling aspen takes little 
part in the early development of a heath. But by the time the 
various groups of hawthorn and hazel begin to run together, it 
appears and multiplies very rapidly ; often it drives out its prede- 
cessors. The aspen is enabled to do so, because it spreads by root 
suckers ; plants that send out many of these, remain shrubby in- 
stead of assuming tree form like their brethren in the forest. 
After a thicket of this kind has grown to be rather dense, a con- 
siderable accumulation of humus may take place and much more 
mesophytic conditions be produced. This shows itself at once in 
the character of the herbs covering the soil. 
As long as the heath character is still pronounced, few foreign 
species are found in the Poa sward. Among these few are Ranun- 
culus fascictilaris, Viola pedafa (apparently not found east of the 
Kettle Range), Verbascum thapsus, Antcnnaria plantaginifolia, 
and the ever-present dandelion. The incipient thickets harbor 
Viola sororia, Anemone nenwrosa, Anemone nitttalliana, Fra- 
garia. When the thicket becomes quite dense, one may find 
Viola ohliqua, Ranunculus ahortiviis, Hepatica, Podophyllum pel- 
tatum, and now and then even so distinctively a mesophytic herb 
as Trillium grandiflonim. By the time this stage is reached, 
numerous young oaks, hickories and black cherries have usually 
appeared, which gradually overtop the shrubs, so that the latter 
thereafter form the underwood in an oak forest. It appears, 
therefore, that the most mesophytic stations in this region are not 
the forests, but the thickets which precede them. 
