BOTANIC MATERIA MEDICA, 2I 
A KEY TO THE NATURAL ORDERS OR 
FAMILIES OF PLANTS DESCRIBED 
IN THIS WORK. 
SERIES 1.—Flowering plants. Plants with 
flowers, having stamens and pistils, and pro- 
ducing seeds, which contain an embryo. 
Crass 1, — Exogenous or Dicotyledonous 
plants. Stems distinctly formed of bark, 
wood and pith; the wood in stems lasting 
from year to year, increasing by annual 
layers on the outside next to the bark. 
Leaves netted-veined. Embryo with two 
opposite cotyledons, or (in the Pine family) 
several in a whorl. Parts of the flowers 
usually in fives or fours. 
Sub-class 1. — Angiosperms. Pistils, a 
closed ovary, containing ovuls and becom- 
ing the fruit. Cotyledons, 2. 
Division 1.—Polypetalous. Calyx and 
corolla both present (except in some 
genera of order I); petals entirely 
