STRUCTURE OF HERBACEOUS DICOTYLEDONOUS STEMS 193 
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Fic. 172. — Diagrams of highly magnified sections of an Alfalfa stem. 
A, both cross sectional and lengthwise views of the tissues near the tip of 
the stem. a, epidermis; 2, colienchyma; e, chlorenchyma of the cortex; s, 
starch sheath; 7, pericycle; 6, bast fibers; 4, conductive portion of the phloem 
containing the sieve tubes and companion cells; c, cambium; z, xylem; and 
p, pith; v, vascular bundie. 8B, section farther from the tip, showing cambium 
ring and the closing together of the bundles. Lettering as above. 
