CAPSELLA BURSA.PASTORIS. 223 



The materials needed for studying are alcoholic (or 

 fresh) specimens of roots, stems, leaves, flowers, and 

 pods ; fresh specimens of flower buds ; and potassic 

 hydrate. 



LABORATORY WORK. 

 GROSS ANATOMY. 



A. GENERAL CHARACTERS. Note 



1. The main axis, consisting of a root and stem. 



2. Three kinds of branches : 



a. One on the root, rootlets. 



/>. Another on the stem and simply repeating it, long 



or very short, or represented by small buds. 

 f. The third on the upper part of the stem, each 



bearing a single flower, pedicels. 



3. The position of the stem branches with reference to 

 the stem leaves, axillary. 



4. The nodes and internodes of the stem, as indicated by 

 the insertion of the leaves. 



5. The absence of lateral appendages on the root or its 

 branches ; those of the stem and its branches appear- 

 ing as foliage and flower parts. 



6. The absence of leaves or bracts subtending the pedi- 



cels. 



B. THE ROOT. Clean thoroughly, immerse in water 

 over a dark surface, and note 



1. The arrangement of the branches (rhtzotaxy). 



2. The thickened whitish tips of uninjured rootlets. 



1 A notable peculiarity of the order Cruel/era, of which Capsella is a 

 member, 



