212 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
jumping from one tuft of grass to another may pass over it without 
doing much injury, and the mosses and fruticose lichens are 
mostly in gravelly places, where the vegetation is too sparse to 
make much of a blaze. 
The vegetation of the wet valleys seems to be practically 
exempt from fire. 
Plant census. The approximate relative abundance of the 
species has been ascertained by a rapid reconnoissance method 
which is a crude modification of Clements's quadrant method. 
I have traversed the area on foot repeatedly in every direction 
(mostly in the summers and falls of 1907 to 1909, with a few 
additional observations made in passing through in 1916 and 1917), 
and in so doing have stopped every few yards or rods and jotted 
down the name of every plant in sight, indicating relative abund- 
ance by a somewhat arbitrary scale. When hundreds of such 
little lists are combined they ought to give the relative abundance 
(combined with size and duration) of the species pretty accurately, 
for the largest and most abundant species of course are noted 
oftenest. Herbs which are recognizable only during a brief period 
when they bloom naturally do not figure as largely in the returns 
as the more lasting ones, but that is all right, for the ephemeral 
species do not take as much water, etc., from the soil and make as 
much hay as the others. 
On account of the difficulty of making proper allowance for 
plants of different sizes, ranging all the way from lichens to trees, 
and the great preponderance of one species among the herbs, 
I have not ventured to assign percentages to the several species. 
But when the percentages are finally worked out and arranged in 
numerical order they will probably make something like a geo- 
metrical progression, for in all areas of natural vegetation that are 
large and homogeneous enough there seem to be many more small 
and rare species than large and abundant ones; just as in human 
society there are always more insignificant people than celebrities, 
more poor men than millionaires, or more small towns than large 
cities. 
In the following lists trees, shrubs, herbs, and cellular crypto- 
gams are separated, and arránged in order of abundance in each 
group, as usual. A few of those seen least often are omitted, on 
