466 BICOTYLEDONES. 



Family 21. Leguminosae. 



The most characteristic feature is, that the gynueceumis \-locular 

 and formed of 1 carpel, the ventral suture of which is turned pos- 

 teriorly. The fruit, in most instances, is apod (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 (Bed Clover), or it is indebisceut, in which case it is more or 

 less berry-like (e.g. the Tamarind, Carob-bean), or it is a drupe (e.g. the Ton- 

 quin-beau), or a 1-few-seeded nut (e.g. Melilntus), or a lomentum, -which divides 

 transversely into as many joints as there are seeds (Omithopus, 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 ex- 

 ceptions, , 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 

 gyncecenm 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 germina- 

 tion. The vegetative parts have these features in common, namely, 

 the leaves are scattered, stipulate, and almost always compound. 

 Peculiar s Jeep -movements and sensitiveness are found in some, chiefly 

 in the Mimosas. Many, probably all, Leguminosas have small 

 tubercles on their roots which are produced by a kind of bacterium, 

 and assist in the assimilation of fi-ee nitrogen. Spontaneous move- 

 ments are exhibited by Desmodium gyrans (Telegraph-plant). 



This family is closely allied to the Rosiflorae, 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 endo- 

 sperm. Amygdalaceiz and Chrysobalanacea:, with solitary carpels, approach on 

 one side to the Leguminosae, among which genera with drupes are also found ; 

 Mimosacecc, with their many stamens, form a connecting link on the other 

 side. In this respect the Mimosa-genus Ajfonsea, and certain Casalpineae and 

 Swartzieas, are of special interest in having more than one carpel (syncarp), a 

 condition which is sometimes met with abnormally in other Legumiuosaa, as 

 will as in AmygJalaceae. About 7,000 species of the Legumicosae are known. 



Order!. Caesalpiniaceae. These are leguminous plants with 

 straight embryo and a floicer which is not papilionaceous and has not 



