Fig. 275. Powdered Rhamnus Frangula.

—Bark. (X 210.) col, Collenchyma of the cortex. cr, Prismatic and rosette crystals. fl, Bast fibers with pitted walls. l, l', Bast in longitudinal and transverse sections. pc, p'c', Cortical parenchyma longitudinal and transverse section. ph, Phelloderm. rm, r'm', Medullary ray in tangential and radial section. s, s', Cork in tangential and transverse section. tc, Rows of crystal cells.
—(From Greenish and Collin.)

This image is from Drug Powders (also see Frangula) in Sayre's Manual of Organic Materia Medica and Pharmacognosy, 1917.