Pear, Apple, Mountain Ash and Hawthorn have protogynous flowers which secrete honey, and are conspicuous to ensure insect pollination.—180 species; in the northern temperate regions.—Pear and Apple are especially cultivated as fruit trees in a number of varieties; the Paradise Apple (Pyrus baccata); especially in southern countries also the Quince (from N. Persia and the Caucasian districts), Medlar and Amelanchier vulgaris. Malus pumila (Caucasus, Altai) and M. dasyphylla (Orient, S. Eur.) are regarded as primitive forms of the Apple-tree; M. sylvestris, which grows wild in European forests, appears to have been less used. The early Lake-dwellers in Switzerland had the apple-tree both wild and cultivated.—The original form of the Pear is supposed to be Pyrus achras (Central Asia).—Many of the species of Cratægus, some with double flowers, and Pyrus (Chænomeles) japonica, with brilliant red flowers, are cultivated as ornamental shrubs. Officinal: Quince pips, on account of the mucilaginous testa.—The fruits contain free organic acids and sugar; prussic acid may be obtained from the seeds. The wood of the Pear-tree is used in manufactures.
Family 21. Leguminosæ.
The most characteristic feature is, that the gynœceum is 1-locular and formed of 1 carpel, the ventral suture of which is turned posteriorly. The fruit, in most instances, is a pod (legume), which opens generally along both sutures, the two valves twisting more or less in opposite directions. In other instances it opens along one suture only, or as a pyxidium (Red Clover), or it is indehiscent, in which case it is more or less berry-like (e.g. the Tamarind, Carob-bean), or it is a drupe (e.g. the Tonquin-bean), or a 1–few-seeded nut (e.g. Melilotus), or a lomentum, which divides transversely into as many joints as there are seeds (Ornithopus, see Fig. [513]).
The inflorescences belong to the centripetal type (i.e. indefinite); cymes do not occur. The flowers are zygomorphic, with vertical plane of symmetry, seldom regular; 5-merous with but a few exceptions, ☿, and slightly perigynous. The following diagram is the most general (Fig. [511]): 5 sepals, with the unpaired sepal median and anterior, 5 petals, 5 + 5 stamens, all in alternating whorls, 1 carpel. The calyx is most frequently gamosepalous, the gynœceum is narrowed down at the base to a short stalk and, in the majority, is more or less bent. The seed is most frequently kidney-shaped, with a smooth, hard and shining testa, the hilum being very distinct. Endosperm is wanting, or is reduced to a thin layer, which is of service when the seed swells during germination. The vegetative parts have these features in common, namely, the leaves are scattered, stipulate, and almost always compound. Peculiar sleep-movements and sensitiveness are found in some, chiefly in the Mimosas. Many, probably all, Leguminosæ have small tubercles on their roots which are produced by a kind of bacterium, and assist in the assimilation of free nitrogen. Spontaneous movements are exhibited by Desmodium gyrans (Telegraph-plant).
This family is closely allied to the Rosifloræ, with which it agrees in the scattered leaves, the presence of stipules, the generally 5-merous and most frequently perigynous flowers with eucyclic stamens, and the absence of endosperm. Amygdalaceæ and Chrysobalanaceæ, with solitary carpels, approach on one side to the Leguminosæ, among which genera with drupes are also found; Mimosaceæ, with their many stamens, form a connecting link on the other side. In this respect the Mimosa-genus Affonsea, and certain Cæsalpineæ and Swartzieæ, are of special interest in having more than one carpel (syncarp), a condition which is sometimes met with abnormally in other Leguminosæ, as well as in Amygdalaceæ. About 7,000 species of the Leguminosæ are known.
Order 1. Cæsalpiniaceæ. These are leguminous plants with straight embryo and a flower which is not papilionaceous and has not the same æstivation (Figs. [508–510]); but in reality there is not a single characteristic which absolutely distinguishes them from the Papilionaceæ.—The majority are arborescent; the leaves as a rule are pinnate or bipinnate. The flower is 5-merous, most frequently perigynous and slightly zygomorphic; the calyx is free or gamosepalous, the corolla polypetalous with ascending imbricate æstivation (i.e. the two lowest petals envelop the lateral ones, and these again the posterior; Fig. [508]); 10 free stamens; fruit various.
Figs. 508–510.—Cassia floribunda.
Fig. 508.—Floral diagram.
