498 PHARMACEUTICAL BOTANY 
(4) Stems, leaves, and roots of secondary growth with open 
collateral or (excepting roots) bi-collateral fibro-vascular bundles; 
in stems radially arranged about a central pith. 
(5) Exogenous stems. 
(6) Medullary-rays present in stems and in roots of secondary 
growth. 
(7) Cambium present in the plant axis. 
Fic. 372.—At left, fruiting branch of Black Pepper (Piper nigrum). Portion 
of shoot with inflorescences. Terminal portion of an inflorescence (enlarged). 
(After Wossildo.) 
At right, the Cubeb (Piper Cubeba). a, cluster of fruit; b, staminate flower; 
¢, pistillate flower in longitudinal section; d, fruit in longitudinal section. (After 
Berg and Schmidt.) Both from Gager after Strasburger, Noll, Schenck and Schimper. 
(8) Roots developing secondary structure. 
(9) Flowers usually pentacyclic and tetramerous or pentam- 
erous (parts of each whorl, four or five or multiple thereof), 
with usually a reduced number of parts in the gyncecium. 
This is the largest class of angiosperms containing more than 
100,000 species of described plants which have been grouped 
into 240 families. We shall consider in this chapter only those 
groups of dicotyledons which yield drugs. 
