104 PRACTICAL COURSE IN BOTANY 
Ss eA ys S ( 
LEE EP EV? 
SEAT RS 0 
pera 
Fics. 120-121. — Transverse and longitudinal sections of a fibrovascular bundle 
in the stem of a sunflower. The two sections are lettered to correspond: AJ, pith 
(parenchyma) ; X,xylem region; P,phloém ; R, cortex ; s, spiral ducts; s’, annular 
ducts; t,t, pitted ducts; C, cambium between the phloém and xylem regions; sb, 
sieve tubes; b, bast; e, bundle sheath; tc, cambium (parenchyma) cells; h, wood fibers, 
