302 
PH A RMA COGNOS Y. 
2. CRYSTALS NOT LESS THAN IO A IN DIAMETER. 
* POLLEN GRAINS NUMEROUS. 
135. Caryophyllus. — Light brown ; pollen grains tetra- 
hedral, somewhat spherical, with three pores, about 
15 p in diameter; calcium oxalate in rosette shaped 
crystals 10 to 15 p in diameter, occasionally in crystal 
fibers; sclerenchymatous fibers spindle-shaped, thick- 
walled, strongly lignified and with simple oblique 
pores; ducts spiral, thick- walled ; oil globules numer- 
ous. The powder of clove stems is less aromatic and 
contains numerous nearly isodiametric and irregular 
thick-walled stone cells v r ith numerous canals and also 
scalariform and reticulate ducts. The powder of the 
fruit of cloves (known commercially as the mother of 
cloves) contains numerous single, oblong and irregular 
starch grains with excentral point of origin of growth. 
136. Insect Powder. — (See No. 5.) 
** POLLEN GRAINS FEW. 
f Ducts Present. 
137. Cusso. — Light brown ; calcium-oxalate crystals 
rosette-shaped, about 20 p in diameter; non-secretion 
hairs one-celled, curved, thick-walled, 0'2 to 0'5 mm. 
long ; secretion hairs with two or three-celled stalk, 
glandular head unicellular or consisting of one or two 
pairs of cells; ducts spiral, scalariform, or with bor- 
dered pores ; sclerenchymatous fibers long, thick- 
walled, strongly lignified, with numerous simple 
oblique pores ; parenchyma of pith more or less ligni- 
fied and with simple pores; pollen grains few, some- 
what ellipsoidal, 25 to 40 p in diameter, with three 
pores. 
tt Ducts Wanting. 
138. Viburnum Opulus. — (See No. 141.) 
