BIOLOGY OF HIGHER SEED PLANTS 9 



THE RELATION OF THE CATNIP, EAGWEED, OR ASTER TO 

 THE ENVIRONMENT 



1. Read Chapter I of the text carefully. Indicate in connec- 



tion with a diagram of a catnip, ragweed, or aster the 

 income and outgo of the plant as outlined in Fig. 4 

 of these exercises. 



2. Summarize in your notes the essential differences between 



the income and outgo of the plant sketched and that of 

 a man. Consult Figs. 2 and 3 of the text and the 

 accompanying discussion in Chapter I. 



TREES 

 SPRUCES AND PINES 



1. Form and general arrangement of parts. 



a. Are the pines and spruces of the erect or of the spreading 



type ? Compare them with oaks, maples, and similar 

 trees. What determines the fact that the pine has 

 a continuous excurrent trunk ? What determines 

 the uniform gradation in the length of the branches 

 from the apex to the base of the tree ? Do the 

 branches appear to have any regular arrangement on 

 the trunk ? Eecall your work on the growth of buds 

 and branches in the lilac. 



b. Are the leaves properly disposed over the crown to 



secure the maximum amount of sunlight ? Does the 

 form and the angle of divergence of the upper and 

 lower branches from the tree trunk contribute to the 

 exposure of the leaves to light ? Are the cones and 

 seeds favorably situated for seed dispersal? 



c. Sketch the spruce or pine tree examined, in a manner 



similar to that outlined for the lilac and the herb. 



