Part 77

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.

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.=