April, 1906.] Observations— Flora of the Shale Bluffs. 
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light humus going first, carrying with it the herbaceous plants, 
followed by the shrubs, leaving the larger trees with their securer 
holdfasts until last. The erosion may cease at this point, or it 
may go on until the slope becomes precipitous and is swept of 
its last vestige of vegetation. 
In either case, the plants 
mentioned as being in the 
xerophytic zone above, may 
begin to creep down as soon 
as sufficient earth has been 
washed down to enable them 
to thrive. 
Owing to the great isola- 
tion of the different ravines, 
there is less uniformity in the 
succession of the different 
plant societies than might 
otherwise be expected. Es- 
pecially is this true of the 
earlier stages. Some of the 
first plants to appear on the 
pure exposed shale are the 
annuals Anychia dichotoma, 
A. Canadensis and Oxalis 
stricta. In some places nearer 
to civilization, Melilotus alba 
is one of the earliest occupants of the naked cliffs. In the 
shrubby thicket which follows, there is usually a great dearth 
in the number of species. Rnbus nigrobaccus may be un- 
iformly relied upon to appear first, while V acciniuni vacillans, 
Gaylussacia resinosa, Amelanchier Canadensis and Acer rubum 
are always found in the dryest, hottest and most exposed shales; 
and these, with a carpeting of lichens, mosses and Danthonia, 
may immediately be followed by a young sturdy growth of white 
and red oaks. 
In ravines where the shale is kept moist by springs, or on 
the dry, southern and western exposures. Solidago caesia, S. 
fiexicaulis, Aster macro phyllus , Rubus occidentalis , as well as R. 
nigrobaccus, Hamamelis Virginiana, with ferns, mesophytic 
mosses and liverworts obtain a foothold here, perhaps earlier 
than usual and are quite abundant. 
An interesting plant society was found on a bluff at High 
Banks on the Olentangy River. This magnificent bluff is over 
one hundred feet in height, exposed to the rays of the afternoon 
sun, and in places so steep and the rock so loose that no vegeta- 
tion has been able to gain a foothold. But few trees are found 
on this exposure; straggling and shrubby red and white oaks. 
Fig. 1 . View in upper end of a narrow ravine 
showing character of the vegetation. 
