I30 



PLANT ORGANS OR PARTS OF PLANTS. 



centre resembles that of the outside. The cells are filled 

 with starch and are pitted, and contain few crystals. 



The structure of the stem, or practically the leaf stem, 

 is interesting in that the arrangement of the bundles is 

 very irregular and the bundle is of the closed collateral 



i^9.>>:p^^.£pj'- 



Fig. 29. — Podophyllum in Powder. 

 Starch; Cryst, crystals of calcium oxalate; Ck, corky tissue, side 

 view; PD, duct with bordered pores; RV, PV, reticulated and pitted 

 ducts; Tr, tracheids; SV, spiral vessel ; WF, wood fibres or bast fibres; 

 Par, parenchyma, in longitudinal view; P, parenchyma in cross-sec- 

 tion. 



type, so characteristic of the monocotyledons, though 

 not unknown for dicotyledons, as, for instance, in the 

 stems of Ranunculus. 



Powder. — The most characteristic and conspicuous fea- 

 tures of the powder are starch grains, crystals, vessels, 

 parenchyma, and fibres. Less conspicuous tissues found 



