22 A LABORATORY MANUAL OF BOTANY 
same for the turned-up tip of a branch? Standing a short 
distance from the tree, see whether the leaves present an 
essentially solid surface of green to the sunlight. Then 
standing beside the main stem or climbing up among its 
branches, see whether the leaves grow abundantly on the 
inner part of the tree top. Explain the conditions found. 
What evidence from dead twigs and branches within the 
tree top that conditions were once different? With the 
maple or oak compare other trees, especially the elm and 
pine, showing by notes and sketches their outline of stem 
and branches and where the leaves are borne. Which have 
their branches mostly directed upwards? 
Why do trees growing in a forest become taller than 
those growing in fields? In an open space find two trees 
which have grown quite close together, so that the branches 
from one crowd those from the other. Account for the 
conditions found among the branches. 
LESSON VII 
Plants and the light—rosette and prostrate plants 
Materials—Dandelion, wild lettuce, mullein, plantain, 
sour dock, trumpet-creeper, sweet potato, pumpkin, and any 
species of ivy. 
Observation and study.—Use the plantain as a specimen 
of the rosette form. Study the leaves. Sketch, showing 
various forms and sizes, and indicate the relative height 
on the stem from which each leaf is taken. Note the differ- 
ent positions of the leaves. In notes describe how this ar- 
rangement permits abundant lighting. Compare with the 
other rosette plants. How do dandelion and wild lettuce 
differ from the plantain? What advantages have these two 
plants in the form of their leaves? What would be the re- 
sult if in these rosette plants the large and small leaves 
should change places? What would be the result if the 
