Fig. 106.—Types of Aphanocyclæ (Columniferæ). A, flower and leaf of the common mallow, Malva (Malvaceæ), × ½. B, a flower bud, × 1. C, section of a flower, × 2. D, the fruit, × 2. E, section of one division of the fruit, with the enclosed seed, × 3. em. the embryo. F, diagram of the flower. G, leaf and inflorescence of the basswood, Tilia (Tiliaceæ), × ⅓. br. a bract. H, a single flower, × 1. I, group of stamens, with petal-like appendage (x), × 2. J, diagram of the flower.
The fourth group of the Choripetalæ is the Eucyclæ. The flowers most commonly have the parts in fives, and the stamens are never more than twice as many as the sepals. The carpels are usually more or less completely united into a compound pistil. There are four orders, comprising twenty-five families.
Fig. 107.—Types of Eucyclæ (Gruinales). A, wild crane’s-bill Geranium (Geraniaceæ), × ½. B, a petal, × 1. C, the young fruit, the styles united in a column, × ½. D, the ripe fruit, the styles separating to discharge the seeds, × ½. E, section of a seed, × 2. F, wild flax. Linum (Linaceæ), × ½. G, a single flower, × 2. H, cross-section of the young fruit, × 3. I, flower. J, leaf of wood-sorrel, Oxalis (Oxalideæ), × 1. K, the stamens and pistil, × 2. L, flower of jewel-weed, Impatiens (Balsamineæ), × 1. M, the same, with the parts separated. p, petals. s, sepals. an. stamens. gy. pistil. N, fruit, × 1. O, the same, opening. P, a seed, × 2.
The first order (Gruinales) includes six families, consisting for the most part of plants with conspicuous flowers. Here belong the geraniums ([Fig. 107], A), represented by the wild geraniums and crane’s-bill, and the very showy geraniums (Pelargonium) of the gardens. The nasturtiums (Tropæolum) represent another family, mostly tropical, and the wood-sorrels (Oxalis) ([Fig. 107], I) are common, both wild and cultivated. The most useful member of the order is unquestionably the common flax (Linum), of which there are also several native species ([Fig. 107], F). These are types of the flax family (Linaceæ). Linen is the product of the tough, fibrous inner bark of L. usitatissimum, which has been cultivated for its fibre from time immemorial. The last family is the balsam family (Balsamineæ). The jewel-weed or touch-me-not (Impatiens), so called from the sensitive pods which spring open on being touched, is very common in moist ground everywhere ([Fig. 107], L–P). The garden balsam, or lady’s slipper, is a related species (I. balsamina).
Fig. 108.—Eucyclæ (Terebinthinæ, Æsculinæ). A, leaves and flowers of sugar-maple, Acer (Aceraceæ), × ½. B, a male flower, × 2. C, diagram of a perfect flower. D, fruit of the silver-maple, × ½. E, section across the seed, × 2. F, embryo removed from the seed, × 1. G, leaves and flowers of bladder-nut, Staphylea, (Sapindaceæ), × ½. H, section of a flower, × 2. I, diagram of the flower. J, flower of buckeye (Æsculus), × 1½. K, flower of smoke-tree, Rhus (Anacardiaceæ), × 3. L, the same, in section.
The second order (Terebinthinæ) contains but few common plants. There are six families, mostly inhabitants of the warmer parts of the world. The best-known members of the order are the orange, lemon, citron, and their allies. Of our native plants the prickly ash (Zanthoxylum), and the various species of sumach (Rhus), are the best known. In the latter genus belong the poison ivy (R. toxicodendron) and the poison dogwood (R. venenata). The Venetian sumach or smoke-tree (R. Cotinus) is commonly planted for ornament.