Part 51

_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.”

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.

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._

b. Tetracyclicæ with epigynous flowers.

Family 33. =Rubiales.=

_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.

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_.

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.~

=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).

In some cases there are apparently 4 leaves in the whorl, and then 2 of these are leaves, and the other two are their interpetiolar stipules. When there are apparently 6 leaves, then the two of these which are opposite each other are leaves, and the other four are stipules; if there are several members in the whorl, then a division of the stipules has taken place. The proof of this theory is founded upon the fact that not more than 2 of the leaves of the whorl ever support buds (which, in addition, are seldom of equal vigour), and also that the whorls do not alternate with each other, which, according to the rules of the position of the leaves, they should do if all the members of a whorl had equal value. If there are, for instance, 4 members in two successive whorls, they stand right above one another, and do not alternate. The development and anatomical relations (the branching of the vascular bundles) also point to the same conclusion.~--All the other groups of the order have only 2 small scale-like interpetiolar stipules, or they form at the base of the leaf-stalks an interpetiolar sheath, having often a toothed edge (Fig. 586).--Another characteristic feature in this group is that the calyx is rudimentary, the corolla _valvate_ (Fig. 588), and that each of the two loculi of the ovary has only 1 ovule. The fruit is a _schizocarp dividing into 2 fruitlets_ (Fig. 590). ~The forms of the fruit, as well as many other characters, as, for example, the epigynous flower, the rudimentary calyx, the two free or almost free styles, present interesting analogous resemblances to the polypetalous order of the Umbelliferæ.~ This group has its home chiefly in the temperate regions of the northern hemisphere, especially about the Mediterranean; it is the only group which occurs in this country, represented by 4 genera.

_Galium_ (Cleavers) is almost destitute of a calyx; it has a small _4-partite, rotate corolla_, 4 stamens, and 2 free styles. The fruitlets are _nut-like_. The inflorescence is a paniculate dichasium passing into helicoid cymes.--_Asperula_ (Woodruff) is distinguished from the above by its salver- or funnel-shaped corolla. 1 style.--_Rubia_ (Madder, Figs. 587–590) has almost the same form of corolla as _Galium_, but (most frequently) a _5-merous flower_, and the fruitlets are “_drupes_.” ~_Sherardia_ (Field Madder); the flowers are clustered in closely arranged cymes surrounded by _an involucre_; _the calyx has 6 distinct teeth_, while the number of petals and stamens is 4. The corolla is funnel-shaped.--_Vaillantia._ _Crucianella._~

The DISTRIBUTION OF SEEDS, in some instances, is promoted by hooked appendages on the fruitlets (_e.g._ _Galium aparine_).

The small flowers of the Stellatæ are frequently collected in compact inflorescences, and are therefore rendered more conspicuous; slight protandry is found in some, self-pollination in the species which are less conspicuous. Many species are heterostylous. _Myrmecodia_, _Hydnophytum_, and other genera have large tubers (hypocotyledonous stems), whose labyrinthine cavities and passages are inhabited by ants.

About 4,500 species; tropical or sub-tropical except the Stellatæ; especially American. The tropical ones are mostly trees.--Several are ~OFFICINAL~ on account of the large amount of _alkaloids_ and _glycosides_ which they contain. The most important are the Cinchonas (_Cinchona calisaya_, _C. succirubra_, _C. officinalis_, _C. micrantha_, etc.), whose bark contains the well-known febrifuge and tonic, Quinine, Cinchonin, etc.; Quinine is also found in _Exostemma_, _Ladenbergia_, and _Remijia_. The root “Ipecacuanha” (an emetic) from _Cephaëlis ipecacuanha_ (Brazils). Caffeine is officinal. The use of the seeds of the coffee plant (“the beans”) was first known in Europe in 1583.--There are only a few which contain _aromatic_ properties, principally among the Stellatæ (coumarin in _Asperula odorata_, the Woodruff), in which group _colouring materials_ are also found. The root and root-stalks of _Rubia tinctorum_, the Madder (S. Eur., Orient., Fig. 587), were formerly largely used for dyeing, but are now superseded by the analine colours. Red dyes are also obtained from the roots of species of _Asperula_ and _Galium_. Gambier is a splendid colouring material, obtained from _Uncaria gambir_ (S.E. Asia), which is used in dyeing and tanning.--The order does not furnish many ornamental flowers.

Order 2. =Caprifoliaceæ.= This order agrees with the Rubiaceæ in having opposite leaves and an epigynous flower, most frequently 5-merous with the ordinary tetracyclic diagram, but in some species it is zygomorphic; the corolla has imbricate æstivation, _carpels 3–5, most frequently 3_ (not 2, which is the most usual number in the Rubiaceæ). The fruit is generally a _berry_ or a _drupe_, but the most important, and in any case most easily recognisable feature, is the _absence of stipules_; in exceptional cases, where they are present, they are not interpetiolar, and are most frequently small.--~The majority of plants belonging to this order are shrubs or trees. Compound leaves sometimes occur. Stipules only appear in a few species of _Lonicera_, _Sambucus_ and _Viburnum_; in the common Elder (_Sambucus nigra_) they are in some instances glandular and small, but in other cases larger and more leaf-like (upon long, well-developed shoots); in the Dwarf Elder (_S. ebulus_) they have the normal leaf-like form; in _Viburnum opulus_ they are present as narrow lobes at the base of the petiole; in others they are completely absent. The leaves are frequently penninerved, rarely palminerved. The calyx, as in the Stellatæ and Aggregatæ, is often very insignificant.~

=1.= LONICEREÆ, HONEYSUCKLE GROUP. This has _campanulate or tubular corollas_ which are often zygomorphic; in connection with the length of the corolla the _style is long, filamentous_, and most frequently has a large, capitate stigma. There are _several ovules_ in the loculi of the ovary, and the fruit is most frequently a _berry_.

_Lonicera_ (Honeysuckle). Shrubs, sometimes twiners. The corolla in some species is considerably bilabiate (Fig. 591), with 4 lobes in the upper lip, and 1 in the under lip, but in others more regular, tubular, or campanulate. The flowers are either borne in capitate inflorescences, which are compound and formed of closely compressed 3-flowered dichasia (sect. _Caprifolium_), or in dichasia with 2 flowers (the terminal flower is wanting). The ovaries and fruits coalesce in some (sect. _Xylosteum_). ~The opposite leaves in some species unite with each other and form a broad collar encircling the stem (Fig. 591). Above the primary bud 1–2 accessory buds are often found in the leaf-axils.--_Diervilla_ (_Weigelia_); with a 2-locular, 2-valved capsule.--_Symphoricarpus_ (Snowberry) has an almost regular, funnel-shaped corolla; a peculiar feature is found in the ovary which has 4 loculi, the 2 median having many ovules in 2 rows, all of which are aborted; the 2 lateral ones, on the other hand, each have only 1 ovule which is developed. Different forms of leaves are frequently found on the same branch; they are entire or lobed.~

=2.= SAMBUCEÆ, ELDER GROUP (Fig. 592). This has a _rotate_, _regular corolla_, extrorse anthers, a very short and thick (or almost absent) _style_, with tripartite stigmas, and only 1 pendulous ovule in each of the 3 (-5) loculi of the ovary. The fruit is a “_drupe_” with 1–3 (-5) stones. The inflorescence is made up of _cymes grouped in an umbel-like arrangement_.