Part 50

=A.= The throat of the corolla is without ligules, or with very small ones.--_Pulmonaria_ (Lung-wort); funnel-shaped corolla; a whorl of hairs in the corolla-throat.--_Echium_ (Viper’s-bugloss) has zygomorphic flowers, the plane of symmetry almost coinciding with that of the very well-developed inflorescence (through the fourth sepal); the corolla is obliquely funnel-shaped, the style is more deeply cleft at the apex than in the others; stamens 2 longer, 2 shorter, and 1 still shorter.--_Cerinthe_ has a tubular corolla with five small teeth and two bilocular fruitlets. The bracts are large and leafy, and, like all the rest of the plant, are _almost glabrous_.--A few _Lithospermum_-species have a naked corolla-throat; others have small hairy ligules, which do not close the corolla-throat. The fruitlets are as hard as stone, owing to the presence of carbonate of lime and silica.--_Mertensia_ (_Steenhammera_); _Arnebia_; _Nonnea_ (small ligules).

=B.= The corolla-throat is closed by, or in any case provided with _ligules_, _i.e._ scale-like bodies or small protuberances, situated in the throat of the corolla _opposite_ the petals, and which are invaginations or _internal_ spurs of the petals (Fig. 572 _D_).--The nuts in _Cynoglossum_ (Hound’s-tongue) bear _hooked bristles_ over the entire surface, or, in _Echinospermum_, only on the edge. The following have smooth nuts:--_Symphytum_ (Comfrey) has a cylindrical, campanulate corolla, and prolonged-triangular, pointed ligules.--_Borago_ (Borage) has a rotate corolla with projecting, emarginate ligules; the stamens have a horn-like appendage, projecting upwards from the back of the filament. The fruitlets are hollow below.--_Anchusa_ (Alkanet, Fig. 572). The corolla is salver-shaped; the ligules small, hairy protuberances. _A. (Lycopsis) arvensis_ has an S-curved corolla-tube.--_Myosotis_ (Forget-me-not, Fig. 573); rotate corolla with small (yellow) protuberances in the throat; scorpioid cyme without floral-leaves; fruitlets flat.--_Omphalodes_; fruitlets hollow at the back, with a scarious, turned-in, toothed edge.--_Asperugo_ (Mad-wort); the calyx grows after flowering, becoming large, compressed, and deeply bifid.

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.

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.

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._

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.

=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._

=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.

=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.~

=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.

Family 32. =Contortæ.=

_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_).

=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.~

=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.