lO 



PHARMACEUTICAL BOTANY 



Fig. 6. — Closed bundle of stem of Zea mays. VG, Bundle sheath; L, inter- 

 cellular space; A, ring from an annular tracheal tube; SP, spiral tracheal tube; 

 M, pitted vessels; V, sieve tubes; S, companion cells; CP, crushed primary sieve 

 tubes; F, thjn- walled parenchyma of the ground or fundamental tissue. {From 

 Sayre after Strasburger.) 



Fig. 7. — Transverse section of a concentric bundle from the rhizome of Iris 

 Xylem surrounding the phloem. I, Tracheae; t\ protoxylem; s, sieve tubes; g 

 companion cells of the internal phloem portion. {From Sayre after Vines.) 



g- 



