MICROSCOPICAL DESCRIPTION 525 



collapsed ; cells of cotyledons, isodiametric or elongated with numerous oil globules 

 and aleurone grains. 



39ia. PETROSELINUM 



Powder. Grayish -brown ; fragments of pericarp of yellowish-brown cells in 

 which are the light yellow oil reservoirs; endosperm cells having numerous aleurone 

 grains each with a rosette of calcium oxalate (3 to. 7 p in diam.) ; tracheag small, 

 usually associated with sclerenchyma fibers. 



252. PHYSOSTIGMA 



Powder. Grayish- white; ellipsoidal or reniform starch grains numerous (5 to 

 15 n in diam.); cells of seed coats irregular or palisade-like; few small reticulate 

 tracheae. 



275. PILOCARPUS 



Powder. Dark green to brownish; epidermis in surface view of 5 to 6-sided cells 

 containing elliptical stomata about 30 n long and usually surrounded by 4 neigh- 

 boring cells ; tracheae spiral, reticulate or with bordered pits, and usually associated 

 with wood-fibers; few bast fibers; rosettes of calcium oxalate (10 to 25 ju in diam.); 

 fragments with large oil reservoirs; few non-glandular hairs. 



89. PIPER 



Powder. Brown or grayish-brown; nearly spherical starch grains (l to 3 /^ in 

 diam.) mostly in the angular cells of the endosperm; stone cells, varying from thick- 

 walled isodiametric or elongated to unevenly thickened and rather thin-walled, 

 and usually filled with reddish-brown substance; yellowish suberized oil cells; and 

 regular epidermal cells. 



161. PODOPHYLLUM 



Powder. Light brown; starch grains spherical to polygonal, simple or 2 to 

 6 compound (3 to 15 /* in diam.) ; few rosettes of calcium oxalate (about 6 to 8 /x in 

 diam.) ; and occasionally raphides (about 65 p long) ; tracheae reticulate or with sim- 

 ple pores; numerous large thin- walled parenchyma cells; and reddish-brown cork. 

 (See Fig. 88.) 



203. PRUNUS VIRGINIANA 



Powder. Light brown; bast fibers thick-walled usually associated with crystal 

 fibers: stone cells thick- walled, strongly lignified; nearly spherical starch grains 

 3 to 4 M in diam.) ; calcium oxalate in prisms and rosettes (10 to 40 ju in diam.). 



555. PYRETHRUM 



Powder. Light to dark" brown; tracheas reticulate or with simple pits; stone 

 cells in groups with thick, yellowish walls; cork fragments yellowish-brown; irregu- 

 lar masses of inulin in thin-walled parenchyma cells or free. 



287. QUASSIA 



Powder. Light yellow; tracheae large, with simple or bordered pits, usually 

 accompanied by thin-walled wood fibers which have oblique pits; crystal fibers 

 with 4 to 6-sided prisms of calcium oxalate (6 to 30 n in diam.) ; few nearly spherical 

 starch grains (10 to 15 /* in diam.). In Surinam Quassia, calcium oxalate crystals 

 are few or absent. (See Fig. 297.) 



120. RHEUM 



Powder. Orange-yellow to yellowish-brown; starch grains nearly spherical 

 simple or 2 to 4 compound (2 to 20 /* in diam.); calcium oxalate in rosettes (50 to 

 125 ju_in diam.) tracheae, spiral or reticulate. (See Fig. 297.) 



213. ROSA GALLICA 



Powder. Reddish; upper epidermis modified to conical papillae; lower epider- 

 mal cells rectangular, both filled with purplish-red color; loose mesophyll cells; 

 small spiral tracheae. 



47. SABAL 



Powder. Yellowish-brown; thick- walled whitish fragments of endosperm; 

 irregular stone cells (about 125 ju in diam.); parenchyma of the pericarp yellowish 

 to brownish-red. 



