178 



ECOLOGY 



forest floor, try to establish it, noting especially their relation 

 to the relative moisture of the soil and to light. 

 Keferences. Clements, 59 ; Principles, Chapter XXXVII ; 

 Wa rill ing-Groom-Balf our, 57 ; Schimper-Fisher, 56. 



an. 



Fig. 6. Model for grouping of drawings in type studies 



base of a plant of shepherd's purse (Capsella Bursa-pastoris) , x ^ ; /•, the main 

 root ; B, upper part of the inflorescence, X 1 ; C, two leaves, — I from the 

 upper part; II from the base of the plant, x 1; D, a flower, x 3; E, the 

 same, with sepals and petals removed, X 3; F, petal; G, sepal; H, stamen, 

 X 10; /, filament; an., anther; /, a fruit with one of the valves removed to 

 show the seeds, X 4; J", longitudinal section of a seed, X 8; if, the embryo 

 removed from the seed, X 8; Z, the first leaves (cotyledons) ; St., the stem end- 

 ing in the root ; L, cross section of the stem, X 20; fh., fibro-vascular bundle ; 

 M, a similar section of the main root, x 15 ; N, diagram of the flower. — After 

 Campbell 



160. Field study of zonation. 



A. Select any locality where two 

 meet and determine : 

 1. The characteristic plants of each association 



more plant associations 



