no petals. Of the purslane
family the portulacas of the gardens, and the common purslane or
"pusley," and the spring-beauty (_Claytonia_) (Fig. 98, _A_) are the
commonest examples. The pink family is represented by many common and
often showy plants. The carnation, Japanese pinks, and sweet-william,
all belonging to the genus _Dianthus_, of which there are also two or
three native species, are among the showiest of the family. The genera
_Lychnis_ and _Silene_ (Fig. 98, _L_) also contain very showy species.
Of the less conspicuous genera, the chick-weeds (_Cerastium_ and
_Stellaria_) are the most familiar.

The third group of the _Choripetalae_ (the _Aphanocyclae_) is a very
large one and includes many common plants distributed among five
orders. The lower ones have all the parts of the flower entirely
separate, and often indefinite in number; the higher have the gynoecium
composed of two or more carpels united to form a compound pistil.

The first order (_Polycarpae_) includes ten families, of which the
buttercup family (_Ranunculaceae_) is the most familiar. The plants of
this family show much variation in the details of the flowers, which
are usually showy, but the general plan is much the same. In some of
them, like the anemones (Fig. 99, _A_), clematis, and others, the
corolla is absent, but the sepals are large and brightly colored so as
to appear like petals. In the columbine (_Aquilegia_) (Fig. 99, _F_)
the petals are tubular, forming nectaries, and in the larkspur
(Fig. 99, _T_) one of the sepals is similarly changed.

Representing the custard-apple family (_Anonaceae_) is the curious
papaw (_Asimina_), common in many parts of the United States
(Fig. 100, _A_). The family is mainly a tropical one, but this species
extends as far north as southern Michigan.

[Illustration: FIG. 99.--Types of _Aphanocyclae_ (_Polycarpae_), family
_Ranunculaceae_. _A_, Rue anemone (_Anemonilla_), x 1/2. _B_, a fruit,
x 2. _C_, section of the same. _D_, section of a buttercup flower
(_Ranunculus_), x 11/2. _E_, diagram of buttercup flower. _F_, wild
columbine (_Aquilegia_), x 1/2. _G_, one of the spur-shaped petals, x 1.
_H_, the five pistils, x 1. _I_, longitudinal section of the fruit,
x 1. _J_, flower of larkspur (_Delphinium_), x 1. _K_, the four petals
and stamens, after the removal of the five colored and petal-like
sepals, x 1.]

The magnolia family (_Magnoliaceae_) has several common members, the
most widely distribut