Part 113. The pulse family (Leguminosae). Examples: peanut (Fig. 33), pea (Figs. 37, 38), beans (Figs. 39, 40), gum arabic tree (Fig. 156), tragacanth shrub (Fig. 157), licorice (Fig. 162), locust (Fig. 182), courbariltree and Zanzibar copal-tree (Fig. 273), indigo shrub (Fig. 275), and logwood-tree (Fig. 276).

See on pages 408-411 the formulas given for Acacia, Haematoxylon, Hymenaea, Trachylobium, Pisum, Phaseolus, Robinia, Indigofera, Glycyrrhiza, Astragalus, Arachis, and Leguminosae.

In their floral structure many acacias, like the gum arabic tree, approximate closely to certain members of the rose family, notably in the numerous stamens, and regular calyx and corolla. In some species the filaments are more or less coalescent. Stamens thus united are said to be monadel-phous.1 The logwood-tree (Haematoxylon), the courbaril-tree (Hymenaea) and the Zanzibar copal-tree (Trachylobium) present irregular corollas, with the peculiarity that the uppermost petal is at first enfolded by the side ones, and these in turn by the lower pair. A large majority of the family, represented by peas (Pisum), beans (Phaseolus), and the other examples referred to, have what is called a papilionaceous 2 corolla. This consists of five petals: one comparatively large called the standard, which is above the others and enfolds them in the bud; two side ones called the wings; and two lower ones grown together to form what is called the keel. A curious condition of the androecium commonly found with the papilionaceous corolla is that there is one uppermost stamen free from the other nine which are more or less coalescent. Such an androecium is termed diadelphous.3 Another peculiarity usually accompanying the papilionaceous corolla is the irregularity and coalescence of the sepals to form a calyx described as gamosepalous 4 and bilabiate,5 that is to say, consisting of sepals more or less united, so as to form an upper and a lower lip.

1 Mon"a-del'phous - Gr. monos, one; adelphos, a brother; meaning in one brotherhood; indicated by the small parenthesis.

2 Pa-pil"i-on-a'ceous - L. papilio, a butterfly-from the resemblance. This is expressed in the formula by

3 Di"a-del'phous - Gr. dis, two; FAJ}.

4 Gam"o-sep'al-ous - Gr. gamos, union; S).

5 Bi-la'bi-ate - L. bis, two; labium, lip; S|>.

The most distinctive peculiarity of the family is its typical fruit, called a legume.6 This consists of a single carpel which becomes dry and normally splits into two valves by dorsal and ventral sutures. As in the mustard family we found that the radish has an indehiscent pod of two carpels which is essentially a silique in structure, so here in certain genera we find pods of one carpel, essentially legumes, but without the usual mode of dehiscence. Peanuts, for example, though indehiscent, are plainly like pea-pods in most important respects, and both may well be called legumes.

6 Leg'ume - L. legumen, beans, etc., or that which may be gathered by hand without cutting - legere, gather. Its sign is C¡ 0 •

A still stranger modification of legume is the fruit of Haematoxylon which dehisces into two valves but along lines midway between the ventral and the dorsal sutures, as indicated by C¡ - >.

The great majority of our wild or cultivated members of the pulse family may be recognized by their having mostly papilionaceous, or at least irregular corollas, and a single carpel which forms a legume, while in other respects these plants are similar to those of the rose family.

Part 114. The Rose Order

Part 114. The rose order (Rosales) includes several families which agree for the most part with the rose and the pulse family in bearing botryose inflorescences of usually complete perigynous flowers, regular or irregular, having petals at least partly distinct, and pistils with a ventral or axile placenta.

These features are indicated in the formula of Rosales on pages 410, 411.