Part 40

205 genera; more than 3,000 species; especially in the Tropics.--Many are used on account of the oil, and of the pungent (aperient, poisonous, anthelmintic, etc.) properties in the latex or the seeds. OFFICINAL: “Cascarilla-bark” of _Croton eluteria_; the fatty oil of the seeds of _Croton tiglium_ (Trop. Asia); “Castor oil” from _Ricinus communis_ (Africa, and cultivated in all warm climates throughout the world); the glandular hairs of _Mallotus philippinensis_ (“Kamala”); this also yields a red dye. Gum “Euphorbium” is the hardened (resinous) latex of the _Cactus_-like _Euphorbia resinifera_ (Morocco).--NUTRITIVE plants: _Manihot utilissima_ and other species (Maniok, Am.). Their large, farinaceous roots form a very important article of food in the Tropics (Cassava-flour, Tapioca or Brazilian arrowroot). The fresh latex of the root in some species is a powerful poison; but the poisonous properties are diminished by roasting or cooking. _Caoutchouc_ is obtained from _Siphonia elastica_ (Trop. S. Am.). The vegetable tallow of the Chinese tallow-tree (_Stillingia sebifera_) is used in large quantities in soap factories. An indigo-like _dye_ is obtained from _Crozophora tinctoria_, and is also found in _Mercurialis perennis_. Shellac is obtained from _Aleurites laccifera_. ORNAMENTAL plants: _Acalypha_, _Croton_, _Dalechampia_.--_Hippomane_ is poisonous.

Order 2. =Buxaceæ.= This order differs from the Euphorbiaceæ in having the micropyle turned inwards; the ♂-flower has a 4-partite perianth and 4 stamens; the ♀-flower a 6-partite perianth and 3 carpels. Capsule with loculicidal dehiscence, the inner layer being detached elastically from the outer.--30 species. Shrubs without latex and with evergreen leaves.--_Buxus sempervirens_ (Box) is an ornamental shrub (poisonous); it has a very hard and valuable wood which is used for wood-engraving and carving.

Order 3. =Callitrichaceæ.= Aquatic plants, growing at the bottom of shallow water, with opposite, simple, undivided, entire, exstipulate leaves, which are generally crowded and form a rosette in the apex of the branches. The flowers are unisexual (monœcious) and borne singly in the leaf-axils; they have no perianth, but are provided with two delicate bracteoles; the ♂-flowers consist of only _1 terminal stamen_ (Fig. 462); the ♀-flowers of a bicarpellate gynœceum (Fig. 463) which is originally 2-locular, but later on becomes 4-locular, as in the case of the gynœceum of the Labiatæ, by the formation of a false partition-wall; in each loculus there is 1 pendulous ovule with the micropyle turned outwards. Fruit a _4-partite schizocarp_ (Fig. 464). 25 species.--_Callitriche._

Order 4 (?). =Empetraceæ.= 4 species. _Empetrum_; _E. nigrum_ (Crowberry) is a heather-like, moorland, evergreen undershrub with linear leaves, having a deep groove closed with hairs, on the under side. The _erect ovules_ show the greatest deviation from the Euphorbiaceæ. Diœcious (and ☿); S3, P3; in the ♂-flower, 3 stamens; in the ♀-flower, a 6–9-locular ovary. Fruit a _drupe_.

Family 15. =Terebinthinæ.=

The diagram of the flower (Figs. 465–467) is the same as in the Gruinales, namely S, P, A2 and G in whorls of 5 (less frequently 3, 4, 6, 8), and the same modifications also occur with the suppression of the petal-stamens, etc. But a _ring_ or sometimes _cup-like glandular structure_ (_disc_) is found _between_ the andrœcium and the gynœceum (Figs. 465, 466). The flowers similarly are regular, _hypogynous_, ☿ and polypetalous, though exceptions are found to all these characters: thus, for example, united sepals and petals frequently occur, and, in some orders, unisexual flowers by the suppression of one sex. In most cases the flowers are small, greenish-yellow, and arranged in paniculate inflorescences. The carpels (most frequently 5) are free in a few, but generally united into a multilocular gynœceum; rarely more than 1 or 2 ovules in each loculus. The gynœceum in the Anacardiaceæ is so reduced that it has only 1 fertile loculus with 1 ovule.--The _ovules are epitropous_, _i.e._ anatropous with outward-turned raphe (except the Anacardiaceæ).--The majority of the species are trees and shrubs with scattered, often _compound (pinnate) leaves_ without stipules, and as in addition they frequently contain _aromatic, especially turpentine-like substances_, they assume a certain resemblance to the Walnut trees, and were formerly classed with them mainly on this account. In a series of genera the volatile, scented oils are found in special glands in the bark of the branches and in the leaves, in the latter case appearing as _pellucid dots_. This family includes several orders which are somewhat difficult to distinguish from each other.

Order 1. =Connaraceæ.= This order forms the connecting link between Terebinthinæ and Rosifloræ (_Spiræa_) as well as Leguminosæ, with which they are sometimes classed. The flowers have 5 5-merous whorls; 2 ovules in each loculus; micropyle turned upwards. Fruit a _follicle_, rarely a collection of follicles. Seed with aril. Shrubs with scattered (most frequently pinnate) leaves, without stipules. 170 species. Tropical.

Order 2. =Meliaceæ.= Trees and shrubs with scattered, often pinnate leaves without pellucid dots and exstipulate; the leaflets are nearly always entire. Flowers small in paniculate inflorescences. Calyx and corolla 4–5-merous; 2 whorls of stamens; 3–5 carpels in the gynœceum. A very characteristic feature is the union of the filaments into a tube, on the edge of which stipule-like teeth are often found. There are most frequently 2 ovules in the loculi; fruit a capsule with many winged seeds in _Swietenia_ (Mahogany tree; Trop. Am.), _Cedrela_, etc.; berries in others. The wood of _Cedrela_ is used for making cigar boxes. 550 species; tropical.

Order 3. =Rutaceæ.= Leaves glandular with pellucid dots. The type is the same as that of the family. Flowers 4–5-merous. The ovary is most frequently 4–5-grooved. Disc well pronounced, often appearing as a “gynophore.” The majority are shrubs with alternate or opposite, compound, more rarely simple, leaves.

=A.= The ovary is deeply 2–5-cleft with basal styles which are more or less united; the carpels in some genera are entirely free (groups 1, 2). The fruit is capsular and most frequently dehisces like follicles along the ventral suture or septicidally, so that a horn-like internal layer (endocarp) separates elastically from the external layer.

=1.= ZANTHOXYLEÆ. _Zanthoxylum_; _Choisya_; _Evodia_.

=2.= BORONIEÆ. Australia.--_Correa._

=3.= DIOSMEÆ. Heather-like shrubs; Africa.--_Diosma_, _Coleonema_, _Empleurum_ and _Barosma_. OFFICINAL: _Barosma crenulata_ and _betulina_, “broad Buchu leaves” (_B. serratifolia_ and _Empleurum serrulatum_, “narrow Buchu-leaves”).

=4.= RUTEÆ. _Ruta_ (Figs. 465–467) _graveolens_ is an herbaceous, glaucous, strongly smelling plant with bipinnate leaves and yellow flowers; the terminal flower is 5-merous, the others 4-merous (S. Eur.).--_Dictamnus_; zygomorphic flower. ~The individual carpels of the fruit separate from each other, and dehisce like follicles, upon which the internal layer is detached elastically and springs out, carrying the seeds with it. Several species are ornamental plants.~

=5.= CUSPARIEÆ. American. Flowers often zygomorphic with gamopetalous corolla; stamens 5.--_Ticorea_; _Galipea_ (_G. officinalis_; S. Am.; “Cortex angosturæ”); _Cusparia_; _Almeidea_.

=B.= The ovary is entire or only slightly grooved; the style is terminal, undivided. The fruit is most frequently a drupe or berry.

=6.= TODDALIEÆ. _Ptelea_; winged fruit. The buds are enclosed in the leaf-sheath. _Skimmia_; _Phellodendron_.

=7.= AURANTIEÆ, ORANGE GROUP. Fruit a berry with a leathery external layer.--The most typical flower is found for example in _Limonia_: S5, P5, A5 + 5, G5 (2–5).--_Citrus_ has 4–5–8-merous flowers, a gamosepalous, dentate calyx, free petals, one whorl of stamens which are split irregularly into several bundles (Fig. 470). The fruit is a _multilocular berry_ provided with a thick, tough, outer layer. The juicy pulp, which fills up the loculi and envelopes the seeds, is formed from many large-celled, juicy hair-structures which arise on the inner side of the walls of the loculi and by degrees entirely fill them up; the dissepiments remain thin, and form the partitions so easily separating from each other (Fig. 469). The seeds in many instances are remarkable for containing several embryos. The blade of the leaf is separated from the frequently winged stalk by a _node_ (and hence is a compound leaf with only the terminal leaflet developed?) (Fig. 468); in other genera, as _Triphasia_, there is a fully developed trifoliate leaf. Thorns are frequently developed.--~The species of this genus, which is a native of the warmer parts of S. E. Asia, are very hard to separate. The differences are found in the forms of the fruit, the leaves and the leaf-stalks, and in the number of stamens. _Citrus medica_, “Cedrat” (Ind.); _C. limonum_, “Citron,” “Lemon” (introduced into Italy in the 3rd to 4th century). OFFICINAL: the fruits and essential oil of Lemon. _C. aurantium_ from E. Asia, the Orange (introduced into Italy in the 14th century). _C. vulgaris_ (Fig. 468), Bitter Orange (introduced into Europe at the time of the Crusades); the unripe Bitter Oranges, and peel of the Bitter Orange is officinal; it is from the flowers of this species especially that the essence of Neroli is made. _C. limetta_, _C. bergamia_, Bergamot; essence of Bergamot is officinal. _C. decumana_, Pomalo, a native of the Islands of the Pacific. About 780 species; chiefly tropical.~

Order 4. =Burseraceæ.= Fruit a drupe; 1–5 stones. The bark, as well as the other parts, contain strong aromatic resins and balsams, and hence several species are used: the Myrrh tree, _Commiphora_ (_Balsamodendron_) from Arabia and Africa; OFFICINAL: Myrrha (_Commiphora myrrha_). Mecca-balsam from _C. opobalsamum_, Arabia; E. Africa. The Incense-tree (_Boswellia_) from the same parts of the globe and E. India. The incense of _B. carteri_ is medicinal (Frankincense). The resin (Elemi) of _Protium_-species is officinal, and is used technically for varnish (S. Am.). Takamahaka-resin from _Elaphrium_ (S. Am.) _Protium_ (_Icica_); _Amyris_ (1 carpel). 270 species; tropical.

Order 5. =Zygophyllaceæ.= The majority have opposite, pinnate leaves with stipules. _Leaves without pellucid dots._ The filaments have a scale on the inner side. The most important is _Guaiacum officinale_ (West India), the wood (Lignum Vitæ) of which is very hard and heavy, this wood and Gum-guaiacum are officinal. Others have a peculiar repulsive smell and taste: the Creosote shrub (_Larrea mexicana_) and _Zygophyllum simplex_. _Tribulus terrester_ is a common weed in S. Europe. _Fagonia._ _Peganum harmala_ (South of Russia) yields a red dye.--110 species; especially in the Tropics; several species in sandy deserts. _Nitraria._

Order 6. =Simarubaceæ.= This order is distinguished by the abundance of _bitter_ substances which it contains (Quassine) especially in the bark and the wood. The wood of _Quassia amara_ (Guiana, Antilles) is officinal; _Picraena excelsa_ yields Jamaica Quassia; the bark of _Simaruba_, _Simaba_-species and others is used. _Ailanthus glandulosa_ is a garden plant (pinnate leaves, winged fruit).--110 species. Tropical.

Order 7. =Ochnaceæ.= Flowers diplostemonous, 5-merous. The unilocular ovaries, which are individually free, project considerably into the air around the gynobasic style; 1 ovule in each loculus; the fruitlets are drupes. Shrubs; leaves alternate, with stipules. _Ochna_; _Ouratea_.--160 species; tropical; especially American.

Order 8. =Anacardiaceæ.= The ovary rarely contains more than 1 ovule, even though there be several loculi and several carpels; in _Anacardium_ all the 10 stamens except one become suppressed. Resin passages.--_Anacardium._ The most peculiar feature is the development of the flower-stalk into a fleshy body about the form and size of a pear (_A. occidentale_ from Trop. Am. and _A. orientale_ from E. Ind.) which bears the kidney-shaped nut (the so-called “Cashew-nut”) on its apex. _Mangifera indica_ (the Mango-tree, from E. Ind.) is cultivated in several tropical countries on account of its delicious drupe. Similarly, species of _Spondias_ (_S. dulcis_, Pacific Islands, _S. lutea_). Several species of _Rhus_ are ornamental shrubs in this country, for instance, _R. typhina_ (N. Am.), _R. cotinus_ (the Wig-tree, the _barren_ flower-stalks of the panicles being feather-like and hairy); _R. toxicodendron_ (Poisonous Sumach, from N. Am.) is poisonous. Chinese galls are produced by the sting of a leaf-louse (_Aphis chinensis_) on _R. semialata_ (China), and Japanese wax is from the seeds of _R. succedanea_ (Japan). Considerable quantities of Sumach (_R. coriaria_) are used in tanning and as a black dye. OFFICINAL: the mastic resin of _Pistacia lentiscus_ (the Mastic-tree, from the Mediterranean). The fruits of _Pistacia vera_ (Syria) are edible; _P. terebinthus_ and others yield turpentine.--450 species; tropical.

Order 9. =Icacinaceæ.= Flowers 4–5-merous; haplostemonous; receptacle convex or cup-like surrounding the gynœceum; in the (single) loculus of the ovary, 2 anatropous, pendulous ovules.--200 species; tropical.

Family 16. =Aesculinæ.=

The essential characters of this family are in the main the same as those of the Terebinthinæ and Gruinales. The flowers are hypogynous, perfect, with free petals, 5-merous (S5, P5, typically A5 + 5, all of which, however, are not generally developed; in our native orders there are only 7–8 stamens), and most frequently a _3-merous, 3-locular gynœceum_ (less frequently 2 or 5 carpels with as many loculi). In each loculus there are usually only 1–2 ovules. A deviation from the preceding families is the frequent _zygomorphy_ of the flower, with, as a rule an _oblique_ plane of symmetry (Fig. 471). When a _disc_ is developed it is placed _outside_ the stamens. The majority have no endosperm (Fig. 473).--The members of the family are nearly all trees.

The family is closely allied to the Terebinthinæ, but unlike this it never has aromatic properties, and differs also in the position of the nectary, in the flowers, which are often irregular with a reduction in the number of stamens, and in the ovule which is usually ascending with micropyle pointing downwards (the Terebinthinæ having the micropyle turned upwards), etc. It is also related to Frangulinæ, the Staphyleaceæ being the chief connecting link; but the Æsculinæ generally have compound leaves.

Order 1. =Staphyleaceæ.= Leaves opposite, often compound. Flowers regular, ☿, 5-merous in calyx and corolla, 5-stamened. The stamens are placed _outside_ the nectary. Ovary syncarpous or 2–3-partite with free styles. The capsule is thin, bladder-like, 2–3-locular, opening at the apex, and has several very hard seeds with a shining testa without aril. Endosperm. _Staphylea pinnata_ (S. Europe) and _trifoliata_ (N. Am.) are cultivated in gardens; they have white flowers in pendulous, axillary racemes or panicles.--16 species.--_Staphylea_ is found in the Tertiary of N. America.

Order 2. =Melianthaceæ.= Glaucous shrubs with scattered, pinnate leaves, and large stipules. _Melianthus._--8 species; S. Africa.

Order 3. =Sapindaceæ.= Trees or shrubs, often climbing by tendrils (lianes with anomalous structure of the stem) and with compound leaves. The flowers, in most cases, are small, insignificant, and without scent, and in some polygamous and zygomorphic. S4–5, P4–5, A8 (less frequently 5–10) inside the nectary (disc); ovary generally 3-locular, with 1–2 ovules in each loculus (raphe ventral, micropyle turned downwards). Seed without endosperm, often with an aril. The embryo is often thick and curved (Fig. 473).

_Æsculus_ (Horse-Chestnut). Trees with opposite, digitate, dentate leaves without stipules; the inflorescence is composed of unipared scorpioid cymes arranged in a pyramidal panicle (termed a thyrsus). The flowers are irregular, with an _oblique plane of symmetry_ (through the 4th sepal, Fig. 471); there are 5 sepals, 5 free petals, of which the one lying between S^3 and S^5 is the smallest (see Fig. 471) and may be absent; stamens 7 (5 + 2), three being suppressed; gynœceum simple, 3-carpellary and 3-locular, with single style; of the two ovules one is ascending, the other descending (Fig. 472).--The fruit is a 3-valvate, sometimes spiny, capsule, with loculicidal dehiscence, the seed having a large hilum, a curved embryo without endosperm and united cotyledons (the radicle lies in a fold of the testa, Fig. 473). _Æ. hippocastanum_ (Greece, Asia), introduced into cultivation about 300 years ago; the majority of the other species, _e.g. Æ. pavia_, etc., several of which are frequently cultivated in gardens, are from N. America. ~The flower of the Horse-Chestnut is adapted for bees, whose abdomen touches the anthers or style when visiting the flower. The flowers are protogynous.~

The other Sapindaceæ have most frequently 4 sepals, 8 stamens, various fruits (septicidal capsule, nuts with or without wings, schizocarp), etc. _Serjania_, _Cardiospermum_, _Sapindus_, _Koelreuteria_, etc. (about 118 genera, 970 species). The seeds of _Paullinia sorbilis_ contain caffeine, and are used as “Pasta guaranà,” in the North Western Brazils in the manufacture of a common drink. _Nephelium_ (or _Euphoria_) _litchi_ (with edible aril), and other species, from Asia.

Order 4. =Aceraceæ.= This order is so closely allied to the Sapindaceæ, that some authorities have classed it with them. The main difference is in the _regularity_ of the flowers, and the =2=-merous gynœceum (in abnormal cases several carpels occur).--They are trees, and, like the Horse-Chestnuts, have opposite leaves without stipules; in _Acer_ the leaves are palminerved, but imparipinnate in _Negundo_, a plant frequently cultivated in gardens. The flowers are often unisexual, polygamous (some species have ☿-, ♂-and ♀-flowers); sepals 5, petals 5 free, =stamens 8= (that is, 5 + 5, but the two median ones are absent) inside a large disc. Fruit a samara (schizocarp) with 2 _winged, nut-like_ fruitlets (Fig. 474). In each of the 2 loculi of the ovary are 2 ovules. Embryo _curved_, with thin, _folded_ cotyledons. Endosperm absent.--~The inflorescences are racemes with a more or less elongated main axis and terminal flower (which sometimes has 10 stamens); when the lateral branches are developed they are similar to the main axis. In some species both corolla and petal-stamens are suppressed. _Acer_ is pollinated by insects, _Negundo_ by the wind.--88 species; North Temperate zone. _Acer_ in the Tertiary from the Oligocene. The following are native plants: Maple (_Acer campestre_), Sycamore (_A. pseudoplatanus_, doubtful native). Important as avenue trees and timber. Sugar is obtained from the spring sap of the Sugar Maple (N. Am.).~

Order 5. =Malpighiaceæ.= A tropical (especially American) order closely related to the Aceraceæ, having often the same form of fruit (but 3-partite). Some species are lianes with anomalous stem-structure. Leaves opposite. The flowers are regular or obliquely zygomorphic (the plane of symmetry passing through sepal 3), with S5, P5, A5 + 5, G3; 1 pendulous ovule in each loculus. Important characteristics for identification are the numerous grandular structures on the sepals. Peculiar 2-spined hairs are found in some. _Malpighia_, _Bunchosia_, _Galphimia_, _Tetrapterys_, _Heteropterys_, etc.--About 600 species.

Order 6. =Erythroxylaceæ.= Sepals 5, petals 5 (with a ligular corona), 10 stamens in one bundle. Gynœceum 3-locular. Fruit a drupe. Tropical (especially American) trees and shrubs, the _Coca-plant_ (_Erythroxylon coca_) being best known. Its leaves are considered by the inhabitants of Chile and Peru to be one of the indispensable necessaries of life; they are chewed, and possess intoxicating, exhilarating properties, and contain the alkaloid cocaine, which is frequently employed as a local anæsthetic.--103 species; chiefly in America.

Order 7. =Vochysiaceæ.= Trees; Trop. Am. 1 stamen.--140 species.

Order 8. =Trigoniaceæ.= Shrubs; Trop. Am.--30 species.

Order 9. =Tremandraceæ.= Polygalaceæ with regular flowers.--27 species. Australia.

Order 10. =Polygalaceæ.= Herbs or shrubs (some tropical species are lianes) with scattered (rarely opposite), simple and most frequently quite entire leaves, without stipules. The flowers are usually borne in terminal spikes or racemes, and are strongly zygomorphic (_the plane of symmetry being median_); they have 5 free sepals, the 2 _lateral ones_ of which (4 and 5 in Figs. 475, 476) are very large, _petaloid_, and frequently project on each side like the “wings” of a Pea-flower; petals 5, of which the two lateral ones are wanting or rudimentary (dotted on Fig. 475), and the _anterior_ “the _keel_” (Fig. 476 _c_) is large, hollow and boat-shaped, and frequently with a lobed or fimbriated edge (Fig. 476 _A_ and _B_, _c_); stamens 8, the two median ones being absent, all _united_ into a tube split along the back, which is also slightly united to the keel (the anthers, often 2 locular, _open by pores_, Fig. 476 _B_, _st_); the 2 median carpels form a bilocular ovary. 1 pendulous ovule in each loculus (Figs. 476 _C_, 475); capsule compressed with loculicidal dehiscence, rarely a nut. _Polygala_ (Milk-wort).

470 species; distributed over the whole globe (none Arctic). OFFICINAL: the root of _P. senega_, from N. Am. Some are used as ornamental plants.

POLLINATION. The flowers of _Polygala_ are pollinated by insects (chiefly bees). The fimbriated processes of the anterior petal support the insect when it alights. The anthers lie on each side of the stigma in the pouch of the anterior petal; the apex of the style is spoon-shaped, and immediately behind it is a viscid stigmatic lobe. In reaching the honey the proboscis of the insect must come in contact with the pollen and the viscid stigma, by which it is rendered sticky; this ensures the pollen adhering to the proboscis and so being carried to other flowers.