The first family (Polygoneæ) is represented by the various species of Polygonum (knotgrass, smart-weed, etc.), and among cultivated plants by the buckwheat (Fagopyrum). The goose-foot or pig-weed (Chenopodium) among native plants, and the beet and spinach of the gardens are examples of the family Chenopodiaceæ. Nearly resembling the last is the amaranth family (Amarantaceæ), of which the showy amaranths and coxcombs of the gardens, and the coarse, green amaranth or pig-weed are representatives.
The poke-weed (Phytolacca) ([Fig. 98], K), so conspicuous in autumn on account of its dark-purple clusters of berries and crimson stalks, is our only representative of the family Phytolaccaceæ. The two highest families are the purslane family (Portulacaceæ) and pink family (Caryophylleæ). These are mostly plants with showy flowers in which the petals are large and conspicuous, though some of the pink family, e.g. some chick-weeds, have 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 Choripetalæ (the Aphanocyclæ) 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 gynœcium composed of two or more carpels united to form a compound pistil.
The first order (Polycarpæ) includes ten families, of which the buttercup family (Ranunculaceæ) 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 (Anonaceæ) 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.
Fig. 99.—Types of Aphanocyclæ (Polycarpæ), family Ranunculaceæ. A, Rue anemone (Anemonilla), × ½. B, a fruit, × 2. C, section of the same. D, section of a buttercup flower (Ranunculus), × 1½. E, diagram of buttercup flower. F, wild columbine (Aquilegia), × ½. G, one of the spur-shaped petals, × 1. H, the five pistils, × 1. I, longitudinal section of the fruit, × 1. J, flower of larkspur (Delphinium), × 1. K, the four petals and stamens, after the removal of the five colored and petal-like sepals, × 1.
The magnolia family (Magnoliaceæ) has several common members, the most widely distributed being, perhaps, the tulip-tree (Liriodendron) ([Fig. 100], C), much valued for its timber. Besides this there are several species of magnolia, the most northerly species being the sweet-bay (Magnolia glauca) of the Atlantic States, and the cucumber-tree (M. acuminata); the great magnolia (M. grandiflora) is not hardy in the northern states.
The sweet-scented shrub (Calycanthus) ([Fig. 100], G) is the only member of the family Calycanthaceæ found within our limits. It grows wild in the southern states, and is cultivated for its sweet-scented, dull, reddish flowers.