
A KEY TO THE FAMILIES. 
A. Parts of the flower nearly always in threes; 
leaves almost always parallel-veined. 
a. Ovary superior. 
b. Leaves often arrow-shaped; pistils many, in a head. 
Alismaceae 
b. Leaves not arrow-shaped; pistil one. Liliaceae 
a. Ovary inferior. 
b. Flowers regular; stamens three. Tridaceae 
b. Flowers irregular; stamensoneortwo. Orchidaceae 
A. Parts of the flower mostly in fours or fives; 
leaves mostly netted-veined. 
B. Corolla absent; calyx mostly present, some- 
times showy. 
a. Ovary superior. 
b. Pistils several to many, distinct. Ranunculaceae 
b. Pistil one, one to several-celled. 
c. Flowers in long spikes with a white involucre 
at base. Saururaceae 
ec. Flowers not in long spikes. 
d. Stipules if present sheathing the stem; 
sepals three to six. Polygonaceae 
d. Stipules absent; sepals mostly five. 
Chenopodiaceae 
a. ae, inferior or appearing so by the closely fitting 
calyx. 
b. Ovary six-celled; stamens six to twelve. 
Aristolochiaceae 
b. Ovary one-celled; stamens three to five. 
c. Leaves opposite; flowers often showy. 
Nyctaginaceae 
c. Leaves alternate; flowers not showy. 
Santalaceae 
B. Both corolla and calyx present. 
C. Corolla of separate petals. 
D. Ovary superior. 
a. Stamens more than ten in number. 
b. Pistils several to many, separate or 
united below. 
c. Pistils separate and distinct. 
d. Pistils enclosed in a hollow recep- 
tacle. 
e. Leaves opposite; petals num- 
erous. Calycanthaceae 
e. Leaves alternate; petals most- 
y five. Rosaceae 
d. Pistils not enclosed in a recep- 
tacle. 
e. Stamens attached to the 
calyx. Rosaceae 
e. Stamens not attached to the 
calyx. Ranunculaceae 
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