678 



SCIENTIFIC AND APPLIED PHARMACOGNOSY 



characteristic are the groups of broadly elliptical stomata about 

 0.035 mm. in length, having wide pores, which project above the leaf 

 surface; and the depressed, multicellular, glandular hairs, having an 

 irregular, ellipsoidal summit, about 0.065 mm. in diameter; cells of 

 mesophyll spheroidal, filled with large chloroplasts, and about 0.010 



FIG. 298. Scaly Grindelia (Grindelia squarrosa). Flowering plants showing the 

 oblong, sharply serrate, sessile leaves; and the heads, composed of numerous 

 imbricated, squarrosely tipped or spreading scales, the yellow ligulate, ray 

 florets directed upwards, and the central cone of numerous tubular florets. 

 From Bulletin 219, Bureau of Plant Industry, U. S. Department of Agri- 

 culure. 



mm. in diameter; large, somewhat elongated, thick-walled, colorless 

 cells of water-storage tissue, mounts in glycerin usually show the pre- 

 cipitation of a granular resinous mass, and acicular or narrow rod- 

 shaped crystals; pollen grains, spheroidal, about 0.035 mm. in 

 diameter, having 3 pores and a spinose cuticle; stem fragments 



