THE ORGANIZATION OF PLANTS INTO SOCIETIES 59 
Observation and study.—Character of the soil—clay, 
sand, rock, loam ? 
Observe the amount of moisture present. If moisture 
is abundant the conditions may be those of hydrophytes. 
If it is scantily supplied, the conditions may be xerophytic. 
Do you find cliffs showing both conditions? 
Observe the exposure to light. Is the slope such as to 
give direct exposure to the sun? 
List the plants found, and notice which are most abun- 
dant. Note which ones grow only near the top of the slope, 
and which grow only at the base. Which ones are found in 
both places? Are the last-mentioned equally vigorous in 
both places ? 
If the slope is quite steep, note how plants hold them- 
selves in place. Examine some specimens from about which 
the earth is being removed. Is any attempt at readjust- 
ment being made? 
Do these plants need deep roots for any other purpose 
than for support? Remove some of the herbaceous plants 
to see concerning the depth to which their roots penetrate. 
Do they have many surface roots? 
If the exposure to the sun is direct you may expect 
the foliage to have some devices for protecting the chloro- 
phyll regions. Determine what some of these are. 
If you can locate one steep slope that is dry and exposed 
to direct sunlight, and another shaded and damp, compare 
the plant life found in each with reference to the following 
points: 
Lists of plants represented. 
Luxuriance of growth. Are plants as large on the ex- 
posed as on the unexposed slope? Note especially the dif- 
ference in the leaves. Which slope shows the greater strug- 
gle for existence between different plant forms? 
Which slope shows the greater struggle with physical en- 
vironment? 
