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AMERICAN JOURNAL OF BOTANY 
[Vol. 9, 
Salix humilis occurred on the upper part of the slope. Dead bur oaks and 
shrubs, from one to five feet high, were scattered sparsely over the slope. It 
seemed probable that these were killed by a more xerophytic period following 
a more mesophytic one in which they had developed. A few bur-oak seed- 
lings were found, but the small leaves, the dryness, and often the yellowish- 
red color of the plants showed the effects of their hard struggle. 
Fig. 2. Portion of a prairie inclusion showing sharp transition to forest. 
Two Stations were selected in the prairie fragment described above and 
four in the shrubs and woods surrounding this fragment. Later in the 
summer two more stations were selected to study another fragment. One 
of the prairie stations in the first remnant was located near the summit of 
the slope, another near the shrubs at the base, called respectively "high 
prairie" and "low prairie" in the following discussion. Two shrub sta- 
tions were located on the gentle slope of the narrow shrub zone at the base 
of the remnant, and about two meters from the edge of the prairie. The 
shrub stations were about ten meters apart. In one, Cornus and young 
Quercus macrocarpa were dominant, while in the other Zanthoxylum ameri- 
canum, Cornus, and Toxicodendron radicans were dominant. The red oak- 
hickory forest station was located about fifteen meters from the base of the 
prairie. The most abundant tree was Quercus rubra, while Hicoria cordi- 
formis and Ulmus fulva occurred frequently. The luxurious undergrowth 
consisted of Quercus rubra, Ulmus fulva, Cercis canadensis L., Hicoria cor- 
diformis, Tilia americana, Parthenocissus quinquefolia. Toxicodendron radi- 
cans, and Symphoricarpos symphoricarpos. The bur- oak forest station was 
