Fig. 572.—Anchusa officinalis: A diagram; the brocteole a is suppressed (dotted); β supports a flower. B, C Myosotis, the fruit, entire and with the calyx in longitudinal section. D, F Alkanna tinctoria: D the corolla opened (4/1); e the ligule; f, g the anthers; E gyncœceum (3/1); F fruit, with three fruitlets; i an aborted loculus; h disc.
Cross-pollination is most commonly effected by insects (especially bees). There are a great many contrivances for pollination; some flowers are protandrous (Echium vulgare, Borago officin.), others are heterostylous (long-and short-styled: Pulmonaria officin.); the corona (ligules) is a protection against rain, and excludes certain insects. Some are barren when self-pollinated (Pulmonaria officinalis, Echium vulgare); others which have but little honey, may, failing insect-pollination, fertilise themselves, and in Myosotis versicolor this regularly occurs by the growth of the corolla during flowering, so that the anthers are brought into contact with the stigma. Honey is secreted on the hypogynous disc.—About 1,150 species, growing especially in the northern temperate zone, Mucilage is found (e.g. in the officinal root of Cynoglossum officinale, in the root of Symphytum): red dyes are found in some roots (e.g. Alkanet-root, the root of Alkanna tinctoria, which is also medicinal; S. E. Europe, Asia Minor); some are poisonous: Cynoglossum, Echium, Anchusa, etc. Several species are ornamental plants. Heliotropium (Peru) is cultivated chiefly on account of its pleasant scent; essential oils are otherwise very rare.
Fig. 573.-Myosotis. Inflorescence and gynœceum.
Order 3. Verbenaceæ. The majority are shrubs; a few are herbs or trees (Teak-tree); some are lianes. The branches are often square. The leaves are opposite or verticillate, without stipules; in some compound. The inflorescences are racemes, spikes, capitula, or dichasia. Five sepals; five petals in a gamopetalous, zygomorphic corolla, which is often bilabiate, but rarely to such an extent as in the Labiatæ, and the upper lip in some is larger than the under, in others smaller; stamens four didynamous, or two; the ovary is entire (not grooved or divided), 1- or 2-locular, or, as in the Labiatæ, divided into four loculi with an erect ovule in each, but in some the anterior carpel is suppressed. One terminal style. The fruit is, e.g. in Verbena, a 4 partite schizocarp with nut-like fruitlets; in Vitex (digitate leaves) a drupe with a 4-locular stone; in Clerodendron a similar fruit, with four free stones; in Lantana a bilocular stone, or two unilocular stones. The radicle is turned downwards. Endosperm small or absent.—Lippia, Stachytarpheta, Bouchea, Priva, Citharexylon, Callicarpa, etc.—The Verbenaceæ are closely allied to the Labiatæ; they differ especially in the ovary not being 4-lobed with gynobasic style, but undivided, almost spherical or ovoid with a terminal style. Again, the leaves are not so constantly opposite, and the inflorescences are various.
730 species; especially in the Tropics; there are several in America, especially Lantana-species; shrubby weeds.—Many of those mentioned are ORNAMENTAL PLANTS, especially Verbena; Vitex agnus castus is a S. European shrub. Lippia citriodora (S. Am.) etc., have strongly-scented leaves; the Teak tree (Tectona grandis) is one of the largest trees in East India, and has a very hard wood.
Avicennia is allied to this order; it inhabits the Mangrove swamps on tropical coasts. The endosperm emerges from the ovule, carrying the embryo with it; the embryo ultimately bursts the endosperm and lies free in the loculus of the fruit; this is then filled by the embryo with its large, green cotyledons, which are borne on an already hairy or rooted stem. The seedling thus developed falls from the tree, together with the fruit, and strikes root in the mud. One special cell of the endosperm at an earlier period becomes a highly-developed organ of suction, growing into a much-branched sac, very rich in protoplasm.
Order 4. Labiatæ. The special characteristics are: the square stem, the opposite leaves (without stipules), the inflorescences which are formed by two double unipared scorpioid cymes, the labiate corolla, the 4 didynamous stamens (the posterior being entirely suppressed) (Fig. 574), and the 4-partite schizocarp with nut-like fruitlets. The floral formula is S5, P5, A5 (the posterior stamen is generally absent), G2.
Fig. 574.—Diagram of Lamium album: sv dichasia.
They are chiefly aromatic plants (herbs, shrubs, e.g. Lavender, or trees), volatile oil being formed in internal cells or in the glandular hairs, which cover all green parts. The stem is always more or less markedly square; the leaves are borne upon the flat sides, and are simple and penninerved, but vary in the other characters. The inflorescences are double unipared scorpioid cymes, which may be situated at some distance from one another in the axils of the foliage-leaves (Fig. 575 A), but frequently when the subtending leaves are bract-like, they are crowded into spike-like inflorescences (Lavandula, Mentha, Salvia, etc.), each of the so-called “whorls” (verticillaster, glomerulus) being a double unipared scorpioid cyme (Fig. 574). (Solitary flowers are found in e.g. Scutellaria, and Origanum). The calyx is strongly gamosepalous, 5-toothed, often bilabiate (Fig. 575 B). The corolla is strongly bilabiate (Figs. 575, 576, etc.), with 2 lobes in the upper lip and 3 lobes in the under lip (an approach to regularity occurs only when the upper lip is small, and thus resembles one lobe, as in Mentha (Fig. 578) and Lycopus, so that the corolla approaches the 4-merous corolla of Veronica and Plantago). The posterior stamen in the diagram (Fig. 574*) is entirely suppressed; in most of the genera the posterior lateral stamens are the smaller (Fig. 575 D), and are entirely suppressed in some (see below); in others, e.g. Nepeta, they are the longer. 2 stamens are found in Salvia, Rosmarinus, Lycopus, etc. The two halves of the anthers are often separated from one another, and are placed at an angle with each other. The gynœceum has 1 style with a bifid extremity (Fig. 575 C) bearing the stigma; the true bilocular ovary is divided by a false partition-wall into 4 loculi, each with 1 erect ovule (Fig. 575 H). These 4 loculi project so strongly that the ovary becomes deeply 4-lobed with the style situated in the centre of the lobes and at their base, “gynobasic” (Figs. 575, 579). A ring-like, often crenate, nectary surrounds the base of the ovary (Fig. 575 G, H). The embryo in this order, as in the Verbenaceæ, is directed downwards (Fig. 575 J) (it is directed upwards in the Boraginaceæ, which have an entirely similar fruit). Endosperm absent.
Fig. 575.—Thymus vulgaris.
The 142 genera are mainly distinguished according to the form of the calyx and corolla, the number, direction, and length of the stamens, the forms of the nuts, etc.
1. Ajugeæ, Bugle Group. Calyx 10-nerved; the upper lip is small; 4 stamens. The ovary is not so strongly lobed as in the following group, so that it is most nearly allied to the Verbenaceæ. The nuts are reticulately wrinkled. Ajuga (Bugle) has a very small upper lip. The upper lip of Teucrium (Germander) is deeply cleft, and the two lobes are bent on their respective sides towards the under lip, which in consequence appears to be 5-lobed, and the upper lip to be wanting.
Fig. 576.—Lamium album: A lateral view of flower; B longitudinal section; C ovary with nectaries (a); D the apex of the style; e, upper lip of corolla; c, b, c the three petals of the lower lip; f anthers; g stigma.
2. Stachydeæ, Betony Group. The calyx is 5- or 10-nerved. The upper lip of the corolla is most frequently strongly arched or helmet-shaped; 4 stamens, the anterior pair the longer (Fig. 576).
a. A somewhat regular and 5–10-dentate calyx with projecting stamens.—Stachys (Betony, Woundwort); the lobes of the under lip are rounded off. The anterior filaments, after pollination, bend outwards. Betonica—Ballota (Horehound); the calyx is funnel-shaped, and has triangular, long, pointed, awn-like teeth.—Galeopsis (Hemp-nettle) has two conical protuberances on the under lip between the lateral and the central lobes. The anthers open by 2 unequal valves. Lamium (Dead-nettle, Fig. 576) has dentate, lateral lobes on the under lip. L. album (White Dead-nettle), L. rubrum, etc. Galeobdolon.—Leonurus; Phlomis.
b. Tubular, regular, often 10-toothed calyx and concealed stamens.—Marrubium vulgare (Fig. 577); 10 calyx-teeth, hooked at the apex; many almost spherical whorls of flowers in the axils of the foliage-leaves, at some distance from one another.—Sideritis.
Fig. 577.—Marrubium vulgare.
c. Strongly bilabiate calyx, the lips closing together after flowering.—Scutellaria (Skull-cap); the two lips of the calyx are entire, the upper lip has a large spur, and drops off on the ripening of the fruit. The flowers are generally solitary and turned to one side.—Prunella (Heal-all); the calyx is compressed, its two lips are strongly dentate, the upper lips closing slightly round the under. The stamens have a tooth-like projection beneath the anthers.
3. Nepeteæ, Catmint Group. 13–15 nerves in the calyx; this deviates from the other groups in the posterior stamens being the longer. The upper lip is slightly arched. Nepeta (Catmint), also Glechoma (Ground Ivy), with regular, and Dracocephalum with irregular calyx.
Fig. 578.—Mentha aquatica, var. crispa.
4. Satureieæ, Mint Group. The upper lip is flat, most frequently ovate, or almost spherical, and emarginate (Fig. 578). The calyx is most frequently 5–10-nerved. 4 stamens, the anterior being the longer; rarely, 2 stamens only.—Mentha (Mint, Fig. 578) has a regular, 5-dentate calyx, a small, almost regular, 4-partite corolla, and 4 erect stamens of nearly equal size. The verticillasters are many-flowered, and are often collected into cylindrical inflorescences. Herbs.—Lycopus (Gipsy-wort); corolla almost regular. 2 stamens, the posterior lateral ones are wanting. Preslia: 4-dentate calyx, 4-partite, regular corolla; 4 stamens of equal size.—Thymus (Thyme, Fig. 575) has a strongly bilabiate calyx, the throat being closed by a whorl of hairs (Fig. 575 B). The corolla is distinctly labiate. Under-shrubs, with small entire leaves; verticillasters few-flowered and separate.—Origanum (Marjoram); spike or capitate inflorescences with the flowers solitary in the axils of the rather large and distinctly 4-rowed (often slightly coloured) floral-leaves. Melissa. Calamintha. Clinopodium (Wild Basil). Satureia. Hyssopus (Hyssop); small, entire leaves; the verticillasters are situated unilaterally in a slender, spike-like inflorescence. Lavandula (Lavender); shrubs with verticillasters collected in cylindrical, long-stalked inflorescences; the calyx is tubular, has 13–15 nerves, the posterior tooth is much larger than the others. Stamens and style do not project. Coleus differs, among other characters, in having united filaments; the stamens and style are bent down and concealed in the boat-shaped under lip.
Fig. 579.—Salvia officinalis.
5. Monardeæ, Salvia Group. Only the 2 anterior stamens are developed.—Salvia (Fig. 579); calyx deeply bilabiate; the upper lip of the corolla is generally strongly compressed. Rudiments of the two lateral stamens are present. The connective in the two fertile stamens is long and filamentous, and bears at the upper end a normal half-anther, but at the lower one a barren, often broader portion, against which the insect is obliged to push its proboscis during its visits to the flowers, causing the pollen-bearing half-anther to be pressed down against its back. Floral-leaves often coloured.—Rosmarinus (Rosemary); a shrub with leathery linear leaves, with rolled back edge. A small tooth on the filament represents the barren half of the anther. Monarda.
The POLLINATION is generally effected by insects, especially bees; the under-lip is the landing-stage and the pollen is deposited on their backs. Cross-fertilisation is promoted by dichogamy; honey is secreted by an hypogynous disc and collected in the corolla-tube. Some genera are homogamous (Lamium, Galeopsis, etc.); others are dichogamous (protandrous); a few are gynodiœcious: ♀-and ☿-flowers in various relative sizes (Glechoma hederaceum, Thymus, Salvia pratensis, and others). The entrance of uninvited guests to the honey is often rendered difficult by whorls of hairs, etc. In numerous instances the upper lip protects the pollen from rain. Cleistogamy is found e.g. in Lamium amplexicaule.
2,700 species; distributed over the entire globe, but the greater number in Mediterranean countries (especially in the Eastern regions), where many are shrub-like.—Poisonous and acrid properties are absent. On account of their volatile oils they are principally used as condiments, for perfumery and in medicine (the officinal parts are therefore nearly always “folia” and “herba,” in Lavandula the flowers, and the volatile oils extracted from them). Such are:[39]Mentha piperita [+] (Peppermint)—menthol is obtained from this species and from M. arvensis—M. viridis [+] (Spearmint), M. crispa (Curly-mint), Thymus vulgaris (Garden Thyme), Melissa officinalis (S. Eur.), Hyssopus officinalis (Hyssop, S. Eur.), Origanum majorana (Marjoram, from the Mediterranean), O. vulgare (Wild Marjoram), creticum, smyrnæum, etc., Salvia officinalis (S. Eur.), Rosmarinus officinalis (oil of Rosemary, S. Eur.), Lavandula vera [+] (oil of Lavender, S. Eur.). Also: Satureia hortensis (S. Eur.), Ocimum basilicum (E. India), Pogostemon patchouli (E. India), etc.—As ornamental plants, e.g. Monarda, Plectranthus, and Coleus (foliage-plants, often with red stems and leaves), Stachys lanata (white, woolly), Phlomis, Salvia-species, Perilla, etc.
Order 5. Selaginaceæ. 130 species; small, most frequently heath-like shrubs or herbs, mainly from S. Africa. They differ from the other Nuculiferæ especially in the bilocular, transversely-placed anthers of the 4 stamens (2 stamens divided as far as the base (?)). The ovary has 2, or by suppression only 1 loculus, each with 1 ovule, and the fruit is a schizocarp dividing into two, or is a 1-seeded nut. Radicle turned upwards.—A few are ornamental plants (Selago, Hebenstreitia).
Order 6. Globulariaceæ. 12 species; especially in the Mediterranean. They form an analogy to the Compositæ, and in the main resemble Jasione montana in appearance, the flowers being crowded into a spherical head (hence their name) and supported by bracts, but without involucre; the ovary is unilocular with 1 pendulous ovule. The 1-seeded nut is enveloped by the persistent calyx. The corolla is more or less labiate, the upper-lip is often absent as in the ligulate corollas of the Astereæ; stamens 4, didynamous, with transversely placed anthers opening by one transverse cleft. The leaves are scattered, simple, entire, and generally form a rosette. Globularia.
Order 7. Stilbaceæ. Heath-like shrubs. The ovary is bilocular; 1 erect seed in each loculus, or the posterior cell is empty. Stilbe. 7 species. S. Africa.
Hypogynous, regular, ☿, gamopetalous flowers (Figs. 581, 582), which are generally 5- or 4-merous, with 5 or 4 stamens (with the exception of Oleaceæ and Jasminaceæ which have only 2 stamens, alternating with the carpels). The gynœceum is formed of 2 (nearly always median) carpels. The corolla very frequently has twisted æstivation (the upper edges of the petals being free; Fig. 581 A), and hence the individual lobes of the corolla are oblique, but the flower as a whole is regularly actinomorphic. A nectary, in the form of a honey-secreting ring or glands, is often found round the base of the ovary.—The leaves, with a few exceptions, are opposite and without stipules. Endosperm large (Fig. 581 C), except in Jasminaceæ and Asclepiadaceæ.
The Apocynaceæ and the Asclepiadaceæ, on account of the free ovaries, without doubt represent a more primitive form, but the Asclepiadaceæ on the other hand form an offshoot on account of their peculiar pollen-masses. The Loganiaceæ form a transition to the Rubiaceæ.
The orders are:—
A. Stamens 5. 1, Gentianaceæ; 2, Apocynaceæ; 3, Asclepiadaceæ; 4, Loganiaceæ.
B. Stamens 2. 5, Oleaceæ; 6, Jasminaceæ; 7, Salvadoraceæ.
Order 1. Gentianaceæ (Gentians). Glabrous herbs, without latex; the opposite, undivided and entire leaves are often slightly united at the base; many have rosette-like radical leaves. Stipules absent. The flowers are generally borne in regular, dichotomously-branched dichasia (Figs. 580, 581 A), which finally become transformed into unipared scorpioid cymes; the parts of the flower are 4–5-merous as far as the gynœceum, which is 2-merous; the calyx frequently is almost polysepalous; the corolla has distinctly twisted æstivation (the upper edges being free) (Fig. 581 A), except Menyantheæ. The carpels are entirely united, and most frequently form a 1-locular ovary with 2 parietal placentæ bearing many ovules (often in several rows, Fig. 581 D, F). Capsule, 2-valved, with septicidal dehiscence, the incurved edges bearing the seeds (Fig. 581 D, F).
Fig. 580.—Erythræa. Inflorescence. 1, 2, 3, etc., the successive shoot-generations.
1. Gentianeæ.—Gentiana (Gentian) has most frequently a tubular, campanulate or funnel-shaped corolla, sometimes with teeth between the corolla-lobes and fringed in the throat of the corolla; G. lutea has a rotate, yellow corolla.—Swertia: rotate corolla; each lobe has at its base 1–2 nectaries, with fringed edges.
Erythræa (Centaury, Fig. 581); corolla most frequently salver-shaped. The anthers ultimately become spirally twisted (E). The style prolonged, deciduous. The flower has the Lobelia-arrangement, i.e. the median sepal is anterior; the corolla is rose-coloured (in the native species). The capsule is semi-bilocular (Fig. 581 F, G).—Cicendia has a low creeping stem, fine as a thread, and small, yellow flowers, 4-merous (without twisted anther).—Chlora (Yellow-wort) 6–8-merous.
Fig. 581.—Erythræa centaurium. Inflorescence, flower and fruit: br1, br2 floral-leaves of the 1st and 2nd order; G a valve of the capsule separated from its fellow.
2. Menyantheæ. Menyanthes (Buck-bean) deviates in several respects from the type of the order. The leaves are scattered and, in M. trifoliata, trifoliate; the corolla has valvate æstivation; the testa is also very hard (thin in the true Gentians). They are aquatic plants with creeping rhizome; the flowers borne in racemes, with terminal flower, heterostylous. The corolla is funnel-shaped with a very hairy throat.—Limnanthemum with floating leaves, like the Water-lilies.
575 species; distributed over the entire globe, but most numerous in Alpine districts. Neither poisonous nor nutritive plants are found, but several are used in medicine on account of the bitter properties so prevalent amongst them. Officinal: the roots of Gentiana lutea. The roots of other species, e.g. G. purpurea, punctata and pannonica (Europe) and the leaves of Menyanthes trifoliata are medicinal. Some are grown as ornamental plants on account of the pure (often deep blue) colour of the flowers.
Order 2. Apocynaceæ (Periwinkles). Trees and shrubs (also lianes), less frequently herbs, generally with latex. The leaves are opposite, simple, entire, without stipules; the flowers are regular; corolla-lobes oblique, æstivation twisted. The stamens are individually free, and the pollen-grains are free or at most united in fours (see Asclepiadaceæ). The two carpels have 2–∞ ovules, in all cases there is only 1 style and a capitate stigma, which towards the base is widened out into a disc-like table (stigma-disc) abstricted in the centre; but the carpels in most of the genera (e.g. those mentioned below) are entirely separate, and the fruit consists of two follicles, the seeds of which often have a tuft of woolly hairs projecting from the micropyle, less frequently of two drupes. In some other genera there is a 1-locular (provided with 2 parietal placentæ) or a 2-locular ovary becoming a 2-valved capsule or a berry. Endosperm abundant.
Vinca (Periwinkle) has a salver-shaped corolla, which is twisted to the left in æstivation (i.e. the left edge of the petals is free); nectaries 2, alternating with the carpels; the summit of the style is hairy. Follicles; seeds without hairs. Mostly creeping, perennial, evergreen plants, whose large flowers are apparently axillary; in reality they are terminal, but by the development of the bud in the axil of one of the two uppermost leaves, they are thus displaced over the other leaf of the pair (a helicoid sympodium being formed).—Plumeria, Tabernæmontana, Cerbera (drupe). Aspidosperma.
Nerium (Oleander). The leaves are in whorls of 3. Corolla funnel-shaped, in æstivation twisted to the right, and with a corona resembling that of Lychnis. The anthers are prolonged at the base and each also bears at the apex a long, linear, hairy appendage; these finally become spirally twisted. Follicles; seeds hairy. Apocynum, Echites, etc. Epigynum is epigynous.
124 genera, 1,000 species; principally in the Tropics. Only 2 species of Vinca are natives of this country; the following are cultivated as ornamental plants:—Vinca minor, V. major, V. (Lochnera) rosea, Amsonia salicifolia, Nerium oleander (Eastern Mediterranean). The latex of some is poisonous (Tanghinia venenifera, Cerbera). Caoutchouc is obtained from others (Hankornia, Landolphia, Vahea, etc.). Tough bast is frequently developed. The bark of Aspidosperma quebracho and the seeds of Strophanthus hispidus are used in medicine (also for African arrow-poison), the latter is officinal.
Order 3. Asclepiadaceæ. A natural and easily recognised order, closely allied to the Apocynaceæ, having, like it, frequently a poisonous latex, opposite, single, entire leaves and fundamentally the same floral diagram and floral structure (S5, P5, A5, G2); but in some the æstivation of the corolla is valvate. The carpels here also have free ovaries, but are united for some distance above into a large, shield-like, 5-angular head, having on its underside the true stigmas, and the fruit always consists of 2 follicles; seeds most frequently numerous and hairy at the micropyle (“vegetable silk”); endosperm scanty.—The order is distinguished from the Apocynaceæ and from all other plants also, except the Orchids, by having all the pollen-grains in each of the 2 loculi of the anthers (true 2-locular anthers) united into one waxy, club-shaped pollen-mass (“pollinium”), for the purpose of pollination by insects. These heavy masses, in order to secure pollination (as in the case of the Orchids), must be attached to sticky discs (corpuscula); there are 5 corpuscula, one at each of the corners of the 5-angular stylar-head (alternating with the anthers), and to each of these are attached 2 pollinia, one from each of the anthers situated on either side (thus each anther gives its right pollinium to one corpusculum and its left to another). The stamens are frequently united at the base, and each bears on the back a variously formed, petaloid appendage, termed a “cucullus.”
Fig. 582.—Asclepias cornuti. A An open flower with the calyx (k) and corolla (c) turned down; the stamens are bent together and surround the gynœceum. B The andrœcium after removal of the sterile part (cucullus) of the anther, which functions as a nectary: e the lateral expansions of the fertile portion of the anthers; f the slit between the expansions of two contiguous anthers, through which the insect’s foot, and later a pollinium which is caught by it, is dragged, and behind which the only receptive part (stigma) is hidden; above the slit f is the gland (r), which secretes the horny corpusculum, which is split at its base and joined on either side with a pollinium (this is more distinctly seen in D and E). When the foot of the insect is caught in the slit (f) and is drawn upwards, it becomes entrapped in the slit of the corpusculum, which is then pulled out together with the pollinia firmly attached to it. In walking over the flowers the insect will draw its foot through other slits (f) and so leave the pollinia on the stigmas. C, D The gynœceum with the pollinia hanging freely. E A corpusculum and two pollinia.
A peculiar relative position (and therefore a good, distinctive characteristic) is often found in the inflorescence, which is cymose; it is placed between the two leaves of a whorl, nearer to one than to the other. The leaf-pairs are placed obliquely in the floral region, at acute and obtuse angles, and not at right angles (as in the purely vegetative parts); the inflorescences are placed in two rows only which are nearly 90° from each other, and the two contiguous to one another are antidromous; they are in reality terminal, each on its own axis, and the entire floral portion of the shoot is a unipared scorpioid cymose sympodium; in addition, complications also arise through individual parts becoming united.—Herbs and shrubs, some twining or climbing.
In Asclepias the corolla is bent back and there is a cup-like cucullus, from the base of which protrudes a horn-shaped body, bent inwards.—Vincetoxicum has a rotate corolla and a ring-like, 5-lobed cucullus, without internal prominences.—Stapelia (especially from S. Africa) is remarkable on account of its Cactus-like, leafless stems and large, brownish flowers, often with carrion-like smell. Periploca has more powdery pollinia (S. Eur., etc.); Hoya carnosa (Wax-flower; Trop. Asia) is a climber, and has small, annual, flower-bearing dwarf-branches. Ceropegia.
201 genera with 1700 species, distributed over all tropical countries; few outside these limits: no native species. Several are used in medicine on account of the pungent properties of the latex. Condurango-bark of Gonolobus condurango is medicinal. Caoutchouc is obtained from the latex of some (e.g. from Cynanchum). The seed-hairs, which are most frequently shining, silk-like, and white, are not sufficiently pliant to be of much value. Ornamental plants in our gardens: Asclepias-species, etc.
Order 4. Loganiaceæ. Ovary single, with two loculi, in structure resembling the Rubiaceæ, but superior. 360 species are included in this order; the majority are tree-like, some lianes which climb by tendril-like branches. The interpetiolar stipules of some species are very characteristic (as in Rubiaceæ, to which they maybe considered to be closely related). The fruit is a capsule or berry. The most familiar genus is Strychnos, which has spherical berries with an often firm external layer, and compressed seeds with shield-like attachments; endosperm abundant. The leaves have 3–5 strong, curved nerves proceeding from the base.—Spigelia.—They have no latex, as in the two preceding orders, but many are very poisonous (containing the alkaloid “strychnine,” etc.); the South American arrow-poison, urare or curare, is made from various species of Strychnos, also an arrow-poison in the East Indian Islands (Java, etc.). Officinal, the seeds of Strychnos nux vomica (“Vomic nut,” Ind.). The seeds of Strychnos ignatii (Ignatius-beans, medicinal), and others are poisonous.
Order 5. Oleaceæ. The leaves are always opposite. The inflorescences are racemes or panicles. The calyx and corolla are 4-merous, more or less united, free in some species; the corolla has most frequently valvate æstivation. All four forms of fruit occur (see the genera). Ovules pendulous, 2 in each loculus (Fig. 583 C). Endosperm oily.—Syringa (Lilac) and Forsythia (anthers somewhat extrose) have capsules with loculicidal dehiscence and winged seeds.—Fraxinus (Ash) has winged nuts (samara) (Fig. 583 D); trees with most frequently imparipinnate leaves; the flowers are naked and sometimes unisexual (polygamous), the Manna Ash (F. ornus) has however a double perianth with 4 free petals (Fig. 583 a); in the native species, F. excelsior, the flowers open before the foliage appears.—Ligustrum (Privet) has berries.—Olea (O. europæa; Olive) has drupes; the pulp and seeds of the ellipsoidal fruits are rich in oil. The lanceolate leaves are grey on the under surface, being covered with stellate hairs. In the wild state it is thorny (modified branches).—Phillyrea; Chionanthus.—Few species of Linociera have 4 stamens.
Fig. 583.—Fraxinus ornus: A flower; ca calyx; co corolla; B gynœceum and calyx; C longitudinal median section of gynœceum; D fruit.
180 species; chiefly in the northern temperate zone. The Olive-tree (Olea europæa) has been an important cultivated plant from ancient times (Olive oil, Provence oil, “Sweet oil”). The best oil is extracted from the fruit-pulp. The fruits are edible. Home: Western Asia, Eastern Mediterranean. Timber: the Ash (Fr. excelsior). Officinal: the Manna Ash (Fr. ornus), cultivated in the Mediterranean countries for the sake of its saccharine juice, which flows out and coagulates into “Manna.”—The following are ornamental plants: species of Ligustrum and Syringa (introduced in the 16th century, from S.E. Europe and Asia), Forsythia (China, Japan; the large, yellow flowers are borne on dwarf-branches with scale-like leaves, before the opening of the foliage-leaves), Chionanthus.
Order 6. Jasminaceæ. The æstivation of the corolla is imbricate; the ovules are erect; seeds almost without endosperm; radicle directed downwards. The number of lobes in the calyx and corolla is not 4, but e.g. 5, 8, 10, and variations are sometimes found in the same individual. The fruit is a berry or capsule. Many species are twiners, and their scattered or opposite leaves are most frequently imparipinnate.—120 species; especially in Trop. Asia (E. India). Some Jasminum-species are cultivated as ornamental shrubs in the warmer districts on account of their elegant foliage, and beautiful, sweet-scented flowers, the essential oil of which is also used in perfumery; the best known are: J. sambac and grandiflorum. Nyctanthes arbor-tristis opens its sweet-scented flowers only at night (E. India).
Order 7 (?). Salvadoraceæ. 8–9 species; Asia, Africa.—Salvadora.
The leaves are always opposite or verticillate. The flower is epigynous, ☿, 5-(or 4-) merous, with the usual sympetalous diagram; 2–5 carpels. The inflorescences are frequently dichasial. The sepals are small, reduced to teeth, and become almost entirely suppressed in the higher forms.—The flower is regular in Rubiaceæ and some Caprifoliaceæ, but in other genera of this latter order (especially of Lonicereæ) it is unsymmetrical. In several genera of the order first mentioned the loculi of the ovary contain many ovules, but in the last the number of loculi and ovules becomes reduced. This is to some extent connected with the nature of the fruit which is many-seeded in most instances, namely a capsule or berry, but in others nut-like. Endosperm is present.
The family on one side is allied to the Contortæ (not only through the Loganiaceæ but also through the Apocynaceæ), and may be regarded as an epigynous continuation of this family; on the other side it is allied to the Valerianaceæ and Dipsacaceæ. Many points of agreement with the Cornaceæ and Araliaceæ are also found, and in fact several Caprifoliaceæ are distinguished from these by hardly any other feature than the gamopetalous corolla.
Fig. 584.—Cinchona calisaya. Flowering branch.
Order 1. Rubiaceæ. Leaves opposite (or verticillate), undivided and entire, with interpetiolar stipules (Fig. 586). Flowers epigynous and hermaphrodite, regular, 4- or 5-merous with the usual arrangement (Figs. 585, 588–590); corolla gamopetalous, in æstivation often valvate; ovary frequently 2-locular.
Fig. 585.—Cinchona calisaya. A entire flower; B after removal of the corolla; C longitudinal section of ovary; D fruit; E seed.
There are no external characters which at once distinguish this exceedingly large order, as in many other natural orders (Compositæ, Umbelliferæ, etc.), but the opposite leaves with interpetiolar stipules form an excellent mark of recognition. It is divided into many sub-orders and groups, especially characterised by the nature of the ovary (1 or several ovules in each loculus), and of the fruit (schizocarp, berry, drupe, capsule).—The corolla is bilabiate in 4 genera; its æstivation in some is twisted; in Capirona, etc., the filaments are of unequal size. The ovary is semi-epigynous in Henriquezia, etc. In Morinda all the fleshy fruits coalesce into one multiple fruit.
1. Cinchoneæ. The fruit is a 2-valved capsule, with many winged seeds (Fig. 585). Cinchona (Quinine, Fig. 584). Trees and shrubs with the foliage and inflorescence somewhat resembling Syringa; the corolla also being of a lilac colour, more or less salver- or funnel-shaped, and frequently edged with a fringe of hairs (Fig. 585), is somewhat similar to that of Menyanthes. Their home is the Andes from Bolivia to Venezuela, varying in altitude from 1–3000 metres. There are now large plantations in Java and E. India. (The name “quinine” is of Indian origin; that of the genus “Cinchona,” is from the Spanish Duchess Cinchon, who in 1638 first introduced the bark into Europe.) The following are closely allied: Cascarilla, Remijia, Ladenbergia, Manettia, Bouvardia, etc.
2. Gardenieæ. Trees and shrubs, frequently having a many-locular berry. Randia, Gardenia, Genipa, Hamelia, etc.
3. Coffeeæ. Only 1 seed in each of the two loculi of the ovary; the fruit is a drupe with 2 stones. Coffea has an ellipsoidal fruit about the size and colour of a cherry; the two thin-shelled, parchment-like stones are enclosed by a thin layer of pulp; the two seeds are flat on the side turned to one another, which has also a deep, longitudinal groove curving to the sides. The endosperm is hard, horny and greyish (without starch); the small embryo lies in the lower end near the circumference. The Coffee-plant (C. arabica) is a small tree, or more frequently, and especially in plantations, a shrub with large dark-green leaves and scented, white flowers. Its home is in Tropical Africa; it is now cultivated in many tropical countries. C. liberica, W. Africa.—Cephaëlis (C. ipecacuanha, Fig. 586; the roots are officinal).—Psychotria, Chiococca, Ixora, Hydnophytum, Myrmecodia, etc.
Fig. 586.—Cephaëlis ipecacuanha. Portion of a branch: st stipules.
4. Spermacoceæ. Chiefly small shrubs and herbs, many of which are weeds in tropical countries. The stipular sheaths bear numerous bristles at the edge. Spermacoce, Borreria, Diodia, Richardsonia, etc.
5. Stellatæ. Herbaceous plants with verticillate leaves (Figs. 587, 588–590); the stipules are large, leaf-like, and resemble the lamina of the leaves, so that the leaves appear to be placed several in a whorl, while in reality there are only two opposite leaves, the stipules of which project freely, and are not erect (Fig. 587).