THE MONOCOTYLEDONS 483 
(6) Medullary-rays generally absent. 
(7) Cambium generally absent. 
Fic. 361.—Pistillate and staminate inflorescences of corn (ea mays). Pistillate 
on left, staminate on right. (Roddins.) 
Druc YIELDING Groups OF MONOCOTYLEDONS 
The Monocotyledons comprise 45 families which contain 
about 25,000 species of described plants. Only those groups 
which yield drugs are considered in this chapter. 
OrDER GRAMINALES 
This is the most important economic order of Monocoty- 
ledons. It contains two families, the Graminee or family of 
grasses and cereals and the Cyperacee or family of sedges. The 
