* 
Observations on the behavior of some species at the edges 
of their ranges* 
ROBERT F. Griccs 
Various writers on ecology and plant geography have spoken 
of the behavior of species at the edges of their ranges—of the 
habitats they affect, of their reproduction, and of their abundance. 
These statements are of course based on impressions from the 
experience of the authors, but there are few extensive records of 
detailed observations on these matters. It is clear that a knowl- 
edge of the causes which set the limits to the distribution of 
species is of fundamental importance to the student of plant 
geography and it is obvious that the termini of the ranges are the 
only localities favorable to the study of these conditions. But an 
understanding of the matter can be reached only after the collec- 
tion of a large amount of detailed evidence from numerous regions. 
It is with the desire of contributing one detail toward such a body 
of evidence that the present observations are published. 
The area in which these observations were made is unusually 
favorable for such studies since a large proportion of the native 
flora here reaches its territorial limits. 122 species, about I3 per 
cent. of the native flora, reach, so far as is now known, the limits 
of their ranges in one direction or another, in the Sugar Grove 
region. This is a narrow strip of country covering the area of 
maximum outcrop of a heavy sandstone, the Black Hand Con- 
glomerate, stretching from the edge of the terminal moraine a 
few miles north of the town of Sugar Grove in Fairfield County, 
Ohio, southward to the valley of Queer Creek, east of South Bloom- 
ingville, in Hocking County. The high cliffs and narrow ravines 
formed in the weathering of this sandstone impart a ruggedness 
to the country which is largely responsible for its botanical interest, 
providing suitable habitats for many of its rare plants and at the 
same time rendering the land unsuitable for agricultural purposes, 
a Contribution from the Botanical Laboratory of the Ohio State University, no, 
79. 
25 
