122 



PLANT ORGANS OR PARTS OF PLANTS, 



chyma. The whole is enclosed in the brown, corky, 

 thick- walled endodermis. The sieve tubes are wider than 

 the surrounding cells. Their cross walls are at right 

 angles or only slightly inclined. They and the side walls 

 show many pores closed by the coagulated protoplasmic 

 substance in which are seen glistening spheres. Without 

 this central circle of fibro-vascular bundles are seen 

 irregularly distributed smaller ones. These lead out- 



FiG. 26. — Powdered Aspidium. 



S, Starch; G, glands; Pr, pitted parenchyma; P, parenchyma; Cr, 



thickened cortical tissues; T, tracheids: O, phloem parenchyma. 



ward to the fronds and have their origin in the central 

 bundles. 



< Powder. — This varies greatly in color according to the 

 age of the specimen, from greenish to yellowish, to yellow- 

 ish-brown. In a powdered condition the color-changes 

 take place more rapidly, even when the powder is kept 

 in a glass-stoppered bottle. 



