Part 68

FIG. 499.--Flower in longitudinal section.

FIG. 500.--Fruit and receptacle in longitudinal section.]

=5.= AGRIMONIEÆ. The receptacle is more or less cup- or bell-shaped, and almost closed at the mouth; it is persistent and envelopes the nut-like fruitlets, but is dry, and in some species hard, the fruitlets being firmly attached to it. In biological connection with this the number of the carpels is generally only 1 or 2, and the whole becomes a false nut (Fig. 500). Herbs.--Agrimonia (Agrimony; Figs. 499, 500); the perianth is 5-merous, stamens 5–20. The receptacle bears externally, on the upper surface, a number of hooked bristles which serve as a means of distribution for the 1–2 achenes which are enclosed in it, and hence the entire flower finally falls off. The inflorescence is a long upright raceme. ~These bristles are arranged in whorls of 5 and 10, of which the uppermost alternate with the sepals.~--Alchemilla (Ladies-mantle; Fig. 501) has 8 green perianth-leaves in two whorls (some authorities consider the four outer as an epicalyx, and the flower therefore apetalous), and 4 stamens alternating with the innermost whorl. There is only one carpel with a basal style and capitate stigma. The flowers are small and greenish, the filaments jointed. The anthers open by one extrorse cleft. The leaf-sheath entirely envelops the stem; the leaves are palminerved. A. aphanes has often only 1–2 stamens. ~The following genera, with 4-merous flowers borne in short spikes or capitula, are allied to this group. Sanguisorba has entomophilous, ☿-flowers with 4(-20) stamens, 1 carpel; stigma papillose.--Poterium; spike or capitulum, the uppermost flowers are ♀, the lowermost ♂, and some intermediate ones ☿ (the order of opening is not always centripetal); S4, P0, A20–30, G2, the long styles having brush-like stigmas (wind-pollination). Leaves imparipinnate.~

POLLINATION. A yellow ring on the inner side of the receptacle, inside the stamens, serves as a nectary when any honey is formed; this, for instance, is not the case in Rosa, Agrimonia, Spiræa ulmaria, S. filipendula, S. aruncus, etc., to which the insects (especially flies and bees) are allured by the quantity of pollen. Homogamy and slight protogyny are frequent, in many instances self-pollination also is finally possible. Poterium, with the long-haired stigma, is wind-pollinated.--About 550 (1100?) species, especially in northern temperate regions.--USES. OFFICINAL: the petals of Rosa centifolia and gallica, the fruits of the Raspberry (Rubus idæus), the rhizome of Geum urbanum, the flowers of the Koso-tree (Hagenia abyssinica or Brayera anthelmintica).--The bark of Quillaja saponaria (Chili) is used as soap and contains saponin. “Attar of Roses” from Rosa damascena, centifolia and other species, especially from the southern slopes of the Balkans. Many species and varieties of Roses are ORNAMENTAL plants: from S. Europe, Rosa lutea (the Yellow Rose), R. gallica (the French Rose) and R. rubrifolia; from W. Asia, R. centifolia, of which the Moss Roses (R. muscosa and cristata) are varieties, and R. damascena; from India and N. Africa, R. moschata (the Musk Rose); from China, R. indica (Tea Rose) etc., besides the native species and the varieties which have been derived from them. In addition, Kerria japonica, species of Potentilla, Rubus odoratus from N. Am., and many species of Spiræa from South-eastern Europe and N. Am. ESCULENT: the “hips” of R. mollissima, R. pomifera, etc.; the fruits of Rubus-species: Raspberry (R. idæus), Cloudberry (R. chamæmorus), Blackberry (R. fruticosus), etc.; of Fragaria-species (F. vesca, collina, grandiflora, etc).

Order 2. =Amygdalaceæ.= Trees or shrubs with rosaceous flowers; leaves simple with caducous stipules; a regular, perigynous flower, the receptacle being partly thrown off by a circular slit; sepals 5, petals 5, stamens 20–30; gynœceum simple, formed of 1 carpel (hence oblique, Fig. 502), with terminal style and 2 pendulous ovules, ripening into a drupe (Fig. 503).--The leaves are penninerved and frequently have glands on the stalks and edges; thorns (modified branches) often occur, i.e. dwarf-branches, which, after producing a few leaves, terminate their growth in a thorn (e.g. Prunus spinosa). ~The vernation of the foliage-leaves varies in the different genera; in the Almond, Peach, Cherry, and Bird-Cherry they are folded; in the Apricot, Plum, Sloe and Bullace, rolled together. In some the flowers unfold before the leaves (Amygdalus, Armeniaca). That the gynœceum is formed of 1 carpel is evident in this as in other instances (e.g. in the Leguminosæ, which are closely related to this order), from the fact that the carpel is oblique, and has only one plane of symmetry, and similarly in the fruit there is a longitudinal groove on one side which indicates the ventral suture. It is only exceptionally that both ovules are developed. In abnormal instances more than 1 carpel is developed.~

=A.= FRUIT HAIRY: Amygdalus (A. communis, Almond-tree) has a dry pulp which is detached irregularly, when ripe, from the wrinkled, grooved, ovoid and somewhat compressed stone.--Persica (P. vulgaris, Peach-tree) differs from the Almond in having a juicy pulp, not detachable from the stone, which is deeply grooved and has pits in the grooves (Fig. 503). (~The name of the genus is derived from Persia, though it is a native of China.~).--Armeniaca (A. vulgaris, Apricot) has a hairy, velvety fruit, but the stone is smooth and has two ribs along one of the edges; the pulp is juicy. (~The generic name has been given on the incorrect assumption that it was a native of Armenia; its home is China.~)

=B.= FRUIT GLABROUS (i.e. without hairs): Prunus (Plum) has a glabrous fruit with bluish bloom; the stone is compressed, smooth or wrinkled. The flowers are borne solitarily or in couples, and open before or at the same time as the leaves; they are borne on shoots without foliage-leaves.--Cerasus (Cherry) has a glabrous, spherical fruit, without bloom, and a spherical stone. The flowers are situated in 2–many-flowered umbels or racemes, and open at the same time as the leaves or a little before them. ~Long-stalked flowers in umbels are found in C. avium (Wild Cherry), C. vulgaris (the cultivated Cherry, from Western Asia); racemes at the apex of leaf-bearing branches and small spherical fruits are found in C. padus (Bird Cherry), C. virginiana, C. laurocerasus (Cherry-laurel), C. mahaleb.~

POLLINATION. Prunus spinosa (Sloe, Blackthorn) is protogynous, but the stamens are developed before the stigma withers. Honey is secreted by the receptacle. Cerasus padus (Bird-Cherry) agrees in some measure with P. spinosa. In the flowers of the Plum and Cherry the stamens and stigma are developed simultaneously and self pollination seems general; the stigma, however, overtops the inner stamens and thus promotes cross-pollination.--DISTRIBUTION. 114 species in the N. Temp, zone; few in the warmer regions; the majority from W. Asia. C. vulgaris, from the regions of the Caspian; Prunus spinosa, insititia (Bullace), domestica (Plum, from the Caucasus, Persia).--USES, principally as fruit-trees: Cherry, Plum, Apricot, etc.; “Almonds” are the seeds of Amygdalus communis (W. Mediterranean), “bitter,” “sweet,” and “shell” almonds are from different varieties, the latter being remarkable for the thin, brittle stone. In the majority of species and in almost all parts of the plant (especially the bark, seed and leaves) is found the glycoside, amygdalin, which forms prussic acid. Many form gum, and the seeds have fatty oils (“Almond oil”). OFFICINAL: the seeds and oil of Amygdalus communis, and the fruit of the Cherry; in other countries also the leaves of C. laurocerasus.--The stems of Cerasus mahaleb are used for pipes. Ornamental Shrubs: Amygdalus nana, Cerasus laurocerasus.

Order 3. Chrysobalanaceæ. Tropical Amygdalaceæ with zygomorphic flower and gynobasic style. 200 species; especially Am. and Asia. Chrysobalanus icaco (Cocoa-plum) is cultivated on account of its fruit (Am.)

Order 4. =Pomaceæ.= Trees and shrubs, most frequently with simple leaves and caducous stipules. The flowers (Fig. 505) have 5 sepals, 5 petals and generally 20 stamens (10 + 5 + 5, or 10 + 10 + 5). There are from 1–5 carpels, which unite entirely or to some extent with each other, and with the hollow, fleshy receptacle (the flower becoming epigynous), (Figs. 505, 506, 507). The carpels are nearly always free on the ventral sutures, rarely free at the sides also. The whole outer portion of the fruit becomes fleshy, but the portions of the pericarp surrounding the loculi (endocarp) are most frequently formed of sclerenchymatous cells, and are more or less firm (the “core”). The nature of the fruit varies, according to the thickness and hardness of the endocarp, being either a “berry” or a “drupe” (see A and B). When the endocarp is thin and parchment-like, the fruit has the characteristics of a berry, each of the 5 loculi generally present containing several seeds; but when this is hard the fruit resembles a drupe, only one seed is developed in each loculus, and the number of the loculi is reduced to one or two. There are nearly always 2 ovules in the loculi of the ovary, but in Cydonia there are a large number in 2 rows. In the genera which have stones, only one seed is developed in each stone. The genera are distinguished mainly in accordance with the kind of fruit and the number of ovules and seeds.

=A.= SORBEÆ. THE ENDOCARP IS PARCHMENT-LIKE OR PAPERY (drupe, with thin stone or berry).

1. Pyrus and Cydonia; carpels completely embedded in the cup-like receptacle, styles always free.--Pyrus: the fruit is glabrous, and has only a small calyx, withering or deciduous, and a 5-locular ovary with at most 2 ascending ovules in each loculus (Fig. 504 D). The large flowers are situated in few-flowered umbels or corymbs. ~P. communis (Pear; free styles, Fig. 507; it has the well-known pear-shaped fruit; the core is reduced to several groups of sclerenchymatous cells embedded in the pulp, the leaf-stalk is as long as the blade).~--Cydonia (Quince) has a hairy fruit with many seeds in 2 rows in each loculus of the endocarp (Figs. 504 C, F; 506); the testa of these seeds is mucilaginous. C. vulgaris, large, terminal flowers on lateral branches, and large leaf-like, persistent sepals.

2. Malus and Amelanchier (Aronia); carpels free on the ventral edge; styles united. Malus communis (Apple) the fruit is “umbilicate” at the base; no sclerenchymatous cells in the pulp; styles united at the base (Fig. 504 D); leaf-stalk shorter than the blade. Sorbus (Mountain-ash) differs only in having a 2–3-locular fruit with extremely thin endocarp. Cymose inflorescences in umbellate cymes. ~S. aucuparia has pinnate leaves, S. aria (White-beam) and other species have simple leaves.--Amelanchier (the Service-tree) has a false divisional wall springing from the dorsal suture, and more or less projecting into each of the loculi of the ovary; Raphiolepis (Fig. 504 E) has racemes and a juicy berry; Eriobotrya japonica (Loquat).~

=B.= CRATÆGEÆ. THE ENDOCARP IS HARD AND BONY (“drupes,” generally with several, sometimes, however, with only 1–2 stones, rarely one multilocular stone; only 1 seed in each of the loculi).--Cratægus (Hawthorn, May). There are 1–5 stones in the spherical or ovoid fruit. The disc, found on the apex of the fruit, inside the small, withered calyx, is small (much less than the transverse section of the fruit). Shrubs with thorns (branches) and moderately large flowers borne in corymbs.--Mespilus (Medlar) differs from the last-named only in having a large disc at the apex of the fruit, inside the large, leaf-like sepals, i.e. almost equal to the greatest diameter of the fruit. The flowers are solitary and terminal.--Cotoneaster is chiefly distinguished from the others by its syncarps, the 2–5 carpels (and stones) being free from one another, and only united to the receptacle by a larger or smaller portion of their dorsal surface (Figs. 504 A, B). Small shrubs with leathery leaves, generally covered with white, felted hairs on the lower surface, and with small flowers; the fruit is red or black.

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.

FIG. 508.--Floral diagram.

FIG. 509.--Flower.

FIG. 510.--The same in long. sect.]

Cassia (Figs. 508–510) is the largest genus (about 200 species); it has an almost hypogynous, zygomorphic flower with 5 free sepals and petals; of the 10 stamens the 3 posterior are generally barren, the others are of very unequal length and open at the apex by pores (Fig. 509). In some (the Senna group) the fruit is a flat, short, thin, dehiscing pod; in others (Cathartocarpus) it is round, long, woody or fleshy, indehiscent, and divided internally by more or less fleshy transverse walls into as many cells as there are seeds.--The following also have DEHISCENT FRUITS: Bauhinia (often lianes, tropical climbers with tendrils [stem-structures] and anomalous stems), Copaifera, Hæmatoxylon (whose pod does not dehisce along the suture, but laterally), Cercis (simple leaves; the corolla resembles that of the Papilionaceæ, but the posterior petal is the smallest, and is enveloped by the 2 lateral ones, which are enveloped in their turn by the 2 anterior).--FRUIT INDEHISCENT: Tamarindus indica; the pod is almost round, often a little abstricted between the seeds; the wall is formed by a thin, brittle external layer, enclosing an acid pulp; well-developed septa are present, between the seeds; the most internal layer is parchment-like. Calyx 4-merous by the coalescence of 2 sepals. Only 3 fertile stamens.--Ceratonia siliqua (Carob-bean, Locusts); the pod is long, compressed, with thick sutures, and has a wall, the central part of which is more or less leathery, fleshy and sweet; there are transverse septa between the seeds, as in the Tamarind. Embryo greenish in endosperm. The flower is without a corolla, 5 stamens.--Pterogyne (winged fruit), etc.--KRAMERIEÆ with Krameria is an anomalous group.

DISTRIBUTION. 80 genera, with 740 species; almost exclusively in the Tropics. The Carob-tree and Cercis grow in the Mediterranean basin. The largest and most widely distributed genus is Cassia, which is found as trees, shrubs, and weeds in all tropical countries. The order has many important uses to mankind. MEDICINAL: the leaves and pods of Cassia acutifolia and angustifolia (officinal, Senna-leaves), the fruit-pulp of the Cassia-sub-genus, Cathartocarpus. Rhatany root from Krameria triandra (Peru, officinal). Balsam is extracted from a number of Copaifera-species (Balsam of Copaiba) from S. Am. (officinal), and from Hymenæa (Copal balsam), Trachylobium and others. Edible fruits are obtained especially from the Carob-tree (from the East) and the Tamarind (officinal). The heart-wood of several species of Cæsalpinia, such as C. brasiliensis (the Pernambuco-tree), echinata (Red-tree), and sappan, yield dyes; Hæmatoxylon (H. campechianum, Logwood), Copaifera bracteata (Amarant-tree).--Timber is obtained from many (Melanoxylon and others). In Europe they are of little importance as ornamental plants, these being confined principally to the species of Gleditschia (G. triacantha, from N. Am.) and Cercis (the Judas-tree, C. siliquastrum, S. Eur.), which are cultivated in gardens; but in tropical gardens beautiful flowering species, e.g. of Cassia, Poinciana, Brownea, are found, and the most beautiful of all ornamental plants, the Indian Amherstia nobilis.

Order 2. =Papilionaceæ.= The flower (Figs. 511, 512) is strongly zygomorphic and somewhat perigynous (Fig. 512 B; most frequently more on one side than the other). The calyx is gamosepalous and persistent. The polypetalous corolla has descending imbricate æstivation, the posterior, large leaf, the standard (Figs. 511 f; 512 B’, e), covering in the bud the two lateral ones, the wings (Figs. 511 v; 512 B’, a), which again cover the two anterior; these are united in the form of a boat, the keel (k and c); the wings and the two petals of the keel are very unsymmetrical. That the keel is formed of two petals is seen by its position (in front of one sepal) and by the two often more or less free claws. The 10 (5 + 5) stamens (monadelphous) are either all united into one bundle, or into two bundles (diadelphous), the posterior one being free (Fig. 512 C). The ovules are curved and also the embryo (Fig. 512 G), especially the hypocotyl, so that the radicle assumes a position close to the edge of the thick, fleshy cotyledons. Endosperm wanting; the cotyledons are very rich in proteid reserve material. The forms of the fruit and exceptions are described under the genera.

Geocarpic fruits, i.e. those which penetrate the soil during their development and ripen underground, are found in e.g. Arachis hypogæa (see page 472), Trifolium subterraneum, Vicia amphicarpæa. Germination takes place in various ways. In the majority the cotyledons are raised above the ground as green, leaf-like bodies; in the Vicieæ they remain thick and white, and are always enclosed in the testa, and are therefore never able to take part in the work of assimilation; in species of Phaseolus, on the other hand, they are raised well above the ground and become green, but remain however thick and fleshy.

=1, 2.= The two groups PODALYRIEÆ (the majority of the genera are Australian) and SOPHOREÆ (Sophora, Edwardsia, etc.), represent the oldest type, as they have 10 free stamens and so form the transition to the Cæsalpiniaceæ. Nearly all are trees and shrubs.