Part 45

_Lythrum_ (Loose-strife). The flower is diplostemonous and 6-merous, with a long, tubular receptacle with epicalyx-teeth (Fig. 519 _c_). The 12 stamens are arranged in two tiers on the inner side of the receptacle. The gynœceum is bicarpellary. ~The flowers are borne in small dichasia in the leaf-axils, and their number is increased by accessory inflorescences beneath the main inflorescence.--The native species, _L. salicaria_, is trimorphic (long-styled, mid-and short-styled forms, Fig. 520). Cross-pollination is chiefly effected by humble-bees and bees, which seek the nectar formed at the bottom of the receptacle. Other species are only dimorphic, or even monomorphic.~--Closely allied are, _Nesæa_, _Diplusodon_, _Lagerstrœmia_, and _Cuphea_, whose flower resembles that of _Lythrum_, but is zygomorphic. In _Cuphea_ the receptacle is oblique and at the back prolonged into a _spur_, in which the nectar, secreted by a gland situated behind the ovary, is collected; the calyx and corolla gradually become reduced in size toward the anterior side of the flower; the reverse, however, is the case with the 11 stamens (the posterior one is absent); the posterior loculus in the bilocular ovary is sometimes barren; the fruit, when ripe, dehisces along the posterior side, the ovary as well as the wall of the receptacle being ruptured by the placenta, which expands and projects freely. ~The flowers stand singly in the centre of the stem, between the pairs of leaves. This may be explained as follows: of the two foliage-leaves in each pair, one supports a foliage-shoot, the other a flower; the foliage-shoot remains in the axil, but the flower is displaced through the length of an entire internode to the next pair of leaves, and then assumes a position between these two leaves. All foliage-shoots stand in two rows, the flowers in two other rows.~

_Peplis_ (Water-purslane), a small, annual plant, with thin, bell-shaped receptacle without projecting nerves. The small flowers have no petal-stamens, and often also no corolla; fruit indehiscent.--_Ammannia_ is closely allied to it.

365 species; 30 genera; mostly in the Tropics, and more especially S. Am.--Some yield _dyes_, _e.g._ _Lawsonia inermis_ (cultivated in Africa and Asia) and _Lagerstrœmeria indica_; some contain tannin; others are ornamental plants, especially in gardens in warm countries.

Order 2. =Blattiaceæ.= 12 species. Tropical Asia and Africa. Trees. Formerly included with _Punica_, but best placed as an independent order.

Order 3. =Melastomaceæ.= A very natural and very large order (150 genera; 2,500 species), its home being chiefly in tropical S. America, especially the Brazils (termed by Schouw “The kingdom of Palms and Melastomaceæ”). There are both herbaceous and arborescent species, which are easily recognized by the opposite or verticillate, simple leaves which have (with the exception of a few heather-like species) 3–5–7–9 curved veins proceeding from the base of the leaf, and connected very regularly by closely parallel, transverse veins. The flower is perigynous or epigynous; its type is that of the Onagraceæ (4–5-merous; 1 whorl of sepals, petals and carpels, 2 of stamens); the calyx is valvate, the corolla is twisted (to the left) in æstivation; the stamens are very characteristic; in the bud they are geniculate; the anther opens in the often long, beak-like, prolonged point, with 1, less frequently with 2 pores, and has generally ear-like appendages at its base. The fruit is a berry or capsule. These large and beautiful flowering-plants play a very important part in South American landscapes; otherwise they are of slight importance (a few are cultivated in conservatories, _e.g._ _Centradenia_, _Medinilla_, _Lasiandra_, _Tibouchina_, _Miconia_, etc.).

Order 4. =Œnotheraceæ= (or =Onagraceæ=). The flowers are arranged in racemes or spikes, ☿, epigynous, regular, polypetalous, _=4=-merous in all 5 whorls_ (1 whorl of sepals, petals and carpels, 2 of stamens); 2–3–5–6-merous flowers are less frequent; _the calyx is valvate_, the _corolla twisted_ in æstivation (the left edge being covered). Gynœceum simple with multilocular ovary; the _style is undivided_, filiform, and bears a capitate or 4-partite stigma; endosperm wanting; embryo straight.--The majority are herbs, especially water- and marsh-plants; several are shrubs. No essential oils. The leaves are alternate or opposite, always single, and without (or with very small) stipules. ~The odourless flowers sometimes have a coloured calyx. In some instances (_e.g._ _Œnothera_, _Fuchsia_) the receptacle is prolonged more or less beyond the inferior ovary, and finally falls off. The stamens are obdiplostemonous (carpels epipetalous); the petal-stamens are sometimes suppressed. The anthers in some genera are divided into storeys. The well-pronounced, triangular pollen-grains are connected together by viscous threads. Small stipules are sometimes found, _e.g._ _Fuchsia_, _Lopezia_.~

=A.= =Fruit a capsule.= _Œnothera_ (Evening Primrose) is 4-merous, has 8 stamens, a tubular receptacle, and an oblong capsule with loculicidal dehiscence leaving a centrally placed column, bearing the seeds.--_Epilobium_ (Willow-herb) deviates from _Œnothera_ especially in the seeds being hairy (at the chalazal end of the seed).--_Chamænerium_ is a Willow-herb with zygomorphic flowers.--~The following may be included here: _Clarkia_, _Eucharidium_ (an _Œnothera_ with 4 stamens and 3-lobed petals), _Godetia_ and _Boisduvalia_, _Jussiæa_ (dehiscence septicidal), _Isnardia_ (petal-stamens absent, sometimes the petals also).--_Lopezia_ has a peculiar, zygomorphic flower (Fig. 521); one of the four sepals is bent forwards and the other 3 backwards; the posterior petals are narrower than the 2 anterior ones which are turned obliquely backwards and bent like a knee, with a greenish nectary at the bend; 2 stamens, one only fertile (the posterior), while the anterior is barren, petaloid, and spoon-shaped; both are sensitive, which is essential for pollination. In Fig. 521, _a_ represents an early stage, in which the stamen and style lie concealed in the staminode; _b_ is the ♂ stage, the stamen projects from the centre of the flower; _c_, the ♀ stage, the style occupies the place of the stamen.~

=B.= =Fruit a berry.= _Fuchsia_ generally has a coloured calyx and tubular receptacle; the corolla may be wanting.

=C.= =Fruit a nut.= _Circæa_ (Enchanter’s Nightshade) has a 2-merous flower (S2, P2, A2 + 0 [petal-stamens are wanting], G2). The flowers are borne in racemes without bracts.--_Gaura._

=D.= =Fruit a drupe.= _Trapa_ (Horn-nut); a peculiar aquatic plant; the submerged stem has long internodes and lanceolate leaves, falling off at an early period, but at each node are found 4 long roots with thin, lateral roots (sometimes erroneously regarded as leaves) borne pinnately; the stem reaching the surface of the water, bears a rosette of rhombic foliage-leaves, with large, inflated stalks containing air, and forming the floating apparatus of the plants. In the axils of the leaves (as in _Gunnera_) 8 small, stipular structures are present. The flowers are solitary in the axils of the foliage-leaves (S4, P4, A4 + 0, G2), _semi_-epigynous. There is an 8-lobed, crenate disc on the free portion of the ovary; one ovule in each loculus. The fruit is a _drupe_ with 4 (or 2) prominent horns (the persistent sepals), which after the pulp has decayed away bear a series of hooks turned downwards on each side, _i.e._ sclerenchymatous bundles which formerly lay concealed in the pulp of the sepals. ~The germination is peculiar: one of the cotyledons is large, and its thick extremity remains in the fruit, the other however is small and is pushed out at the apex of the fruit together with the radicle and plumule; the development of the root soon ceases, and the plumule usually grows into a stem entirely without branches, similar to the one described above, only that 1–2 precisely similar shoots arise in the axil of each cotyledon, so that each embryo produces 3–5 shoots.--_Trapa_, by its mode of life, its 1-seeded fruit, etc., forms a transition to _Haloragidaceæ_.~

The large-flowered forms are adapted for insect-pollination and are often protandrous, the small-flowered ones are homogamous and may pollinate themselves. _Œnothera_ is adapted for hawk-moths and bees.--330 species; especially in temperate climates, chiefly in the Northern Hemisphere. _Epilobium_, _Circæa_ are natives of this country; _Trapa_ is extinct in this country, it has been found in a semi-fossilized condition near Cromer and in bogs in Denmark, and existed in Sweden until a few years ago; _Œnothera_ has been introduced from N. Am.--A number of N. Am. species are grown as ornamental plants in our gardens. The seeds of _Trapa natans_ are edible, and used as food in China.

Order 5. =Haloragidaceæ.= This is a reduced form of the Œnotheraceæ, and principally differs from these in the presence of _endosperm_ and _free styles_. _Only 1 ovule in each loculus._--84 species distributed over the entire globe; the majority are aquatic plants. The most advanced type is _Myriophyllum_ (Water-Milfoil), with a regular, epigynous flower (S4, P4, A4 + 4, G4), most frequently _diclinous_ (monœcious); the fruit is a _2–4-partite schizocarp_. Aquatic plants, most frequently with pectinate, pinnate leaves.--_Haloragis._--~_Gunnera_ (a dozen species from the Southern Hemisphere) forms the next step in the reduction. Large, scattered, rough-haired, and softly-spined leaves, with small flowers in crowded inflorescences. The flower, when most complete, has S2, P2, A2 (petal-stamens) and G2, forming an inferior, unilocular ovary with 1 ovule. It is remarkable for the great number of stipules placed in transverse rows in the leaf-axils, for the peculiar glandular organs, and for the colonies of _Nostoc_, which are found embedded in the cortex as a kind of parasite.~--The simplest form is _Hippuris_ (Mare’s-tail) with an extremely small, crenate or entire calyx, without corolla, and with only one stamen and one carpel, forming an inferior, unilocular ovary with only one ovule. Fruit a drupe with thin pulp. ~It is an aquatic plant with creeping, sympodial rhizome, and erect unbranched shoots, bearing numerous small, verticillate leaves. The small flowers are situated singly in the leaf-axils.~

Order 6. =Rhizophoraceæ.= Tropical trees or shrubs (50 species, the best known being _Rhizophora mangle_, Mangrove) which grow gregariously, especially along the banks of rivers and by sea-coasts, where the water is quiet and brackish, and where they form the so-called Mangrove-swamps. Aerial roots are formed on the stems and branches (Fig. 522 _A_). The seeds germinate in the fruit, which by arrest contains only one seed (Fig. 522 _B_), before it is detached from the tree. The radicle projects considerably from the seed, and hangs down freely in the air; when the embryo is finally detached from the mother-plant, the separation is effected by the hood-like cotyledon, which entirely envelops the plumule, becoming detached from the rest of the embryo, which falls down, while the hood-like cotyledon remains enclosed in the fruit. The embryo, after it has fallen, strikes root, and continues growing in the undisturbed mud under the trees, or perhaps it may first be drifted about by the water, being well adapted for this by its peculiar, tough nature, and large, intercellular spaces.--It may also further be remarked that the anther is divided into a number of small loculi. The leaves are stipulate. The endosperm projects from the micropyle, growing out from the base of the seed, and thus serves as an organ of suction to convey nutriment to the embryo from the mother-plant.

Order 7. =Combretaceæ.= Trees and shrubs, partly lianes. An inferior, unilocular ovary with few pendulous ovules. _Conocarpus_ and _Laguncularia_ form, in conjunction with the species of Rhizophoraceæ, the tropical Mangrove-swamps. _Terminalia._--280 species; Tropics.

Order 8. =Myrtaceæ (Myrtles).= The plants belonging to this order are shrubs or trees, the majority being easily recognised by the vegetative characters. The leaves, for instance, are most frequently opposite, without stipules, undivided and entire, parchment-like or leathery, evergreen, _aromatic_, finely dotted by _pellucid glands containing essential oils_; the venation is penninerved with a nerve just inside and running parallel to the edge of the leaf. The flowers are regular, epigynous (Figs. 523, 524, 525) and ☿, most frequently =4-= or 5-merous in the calyx and corolla, with _many_ stamens (by splitting, so that they are often in several distinct bundles) and an ovary with one style, formed of 2–5–many carpels; the receptacle is most frequently united for its entire length with the ovary. The fruit varies, but is _most frequently a berry_. The embryo is thick, often curved, with united cotyledons; no endosperm.

=1.= MYRTEÆ, MYRTLE GROUP. Chiefly American, though some are found also in Africa and Asia. The fruit is a _berry_ with generally 2–5 loculi in the ovary, and many ovules in each.--_Myrtus_; _Eugenia_ (the petals fall off together as a hood in the Clove, _E. caryophyllata_, Figs. 523, 524); _Myrcia_; _Jambosa_; _Amomis_; _Psidium_, etc.

=2.= PUNICEÆ, POMEGRANATE GROUP. Only 2 species (_Punica granatum_; from Persia, Afghanistan), differing in several respects from the typical form of the Myrtaceæ. The leaves are generally _opposite_, without glands and marginal veins. The receptacle, calyx and corolla are red; the latter 5–8–(generally 6-) merous. Calyx valvate and corolla folded as in Lythraceæ, stamens also and epicalyx as in this order. The most characteristic feature is the inferior, spherical berry, with dry pericarp, formed from two whorls of carpels in two tiers (Fig. 525); the interior whorl, which is also the lower, has 3 carpels, and the placentæ are situated in the inner angles of the 3 loculi; the external whorl is 5-merous, and the placentæ have originally the same position in the inner angles of the loculi, but their position is changed to the outer side of the loculi owing to the growth of the wall of the ovary, which takes place early, causing the carpels to become, as it were, turned inside out, so that the part which was turned downwards is turned upwards, and the part which was turned inwards becomes turned outwards (as in _Mesembrianthemum_). The edible part of the fruit is the _fleshy testa_, as in _Ribes_. The cotyledons are rolled together spirally.

=3.= LECYTHIDEÆ. The majority are South American. The leaves are scattered, without pellucid glands, and frequently dentate. The flowers are zygomorphic. The woody fruits are either indehiscent, or open by a lid. To this belong: _Bertholletia_ (_B. excelsa_), the seeds well known as “Brazil-nuts,” _Lecythis_ (Sapucaia-nuts from _L. ollaria_), _Barringtonia_.

=4.= LEPTOSPERMEÆ. Almost entirely from Australia and the East Asian and Pacific Islands. The fruit is a _capsule_. The leaves are scattered, and in some placed edgewise by the twisting of the leaf-stalks.--_Eucalyptus_, the Australian Gum-tree; the calyx falls off like a lid (Figs. 526, 527). Some of the species attain gigantic heights, _E. amygdalina_ 140–150 m. with a diameter of 8 m. The leaves in _E. globulus_ are opposite and dorsiventral on the young plant; on the older scattered, placed edgewise by the twisting of the leaf-stalk, and isolateral; _Metrosideros_, _Calothamnus_ (stamens distinctly polyadelphous), _Melaleuca_, _Leptospermum_, _Callistemon_ (the flowers are borne in spikes whose axis continues to grow after flowering, thus several zones of fruits may be seen on the same branch).

=5.= CHAMÆLAUCIEÆ. Australian shrubs with heath-like appearance; they differ from the other Myrtaceæ in having a unilocular ovary with few, basal ovules, and a 1-seeded _nut_. The sepals are often pappus-like, and divided into many bristles.--_Chamælaucium_, _Darwinia_, etc.

This large order (2,100 species) is confined almost entirely to the Tropics, being found principally in America and Australia. In Europe, only _Myrtus communis_.--Several are useful on account of the large quantity of _volatile oils_ (contained in internal glands): the flower-buds (“Cloves”) of _Eugenia caryophyllata_ (the Moluccas, cultivated in the Tropics, Figs. 523, 524); the unripe, dry berries (“Pimento”) of _Myrtus pimenta_ (_Pimenta officinalis_, W. Indies); Cajeput oil is extracted from _Melaleuca minor_ and _leucadendron_ (East Asian Islands). _Eucalyptus globulus_ (Australia) has of late years become well known on account of its rapid growth, its hard wood, and its antipyretic qualities; it is cultivated on swampy soils, which it helps to drain.--OFFICINAL: “Cloves,” and the cork of both stem and root of _Punica granatum_. Several have EDIBLE FRUITS, such as _Psidium guyava_ (Guava, var. _pomiferum_ and _pyriferum_, Am.), _Eugenia cauliflora_ and others, _E. jambosa_, _Punica granatum_ (the Pomegranate), etc. EDIBLE SEEDS (with abundance of _fatty oil_): “Brazil nuts” from _Bertholletia excelsa_ (Trop. S. Am.). “Bay-rum” is extracted from the leaves and fruits of the Bayberry-tree (_Pimenta acris_, W. Ind.); Guava-rum from the berries of _Eugenia floribunda_. _Tannin_ is found in large quantities _e.g._ in _Punica_. _Gum_ is formed by many Australian Eucalypti (“Gum-trees”). ORNAMENTAL PLANTS cultivated in this country are: _Myrtus communis_ (Mediterranean), several in conservatories, especially the Australian Leptospermeæ, Eucalyptæ and others.

Family 24. =Umbellifloræ.=

The flower is regular, ☿, and _completely epigynous_, 5- or 4-merous, with =1= whorl of stamens and 5–2 carpels. _Sepals very small, tooth-like._ The _corolla is polypetalous, most frequently valvate in æstivation_ (least pronounced in the Umbelliferous plants). Round the base of the styles, which are generally free, there is an _epigynous_ (undivided, or divided) _nectar-disc_ (“stylar-foot”: Figs. 528 _B_, _C_, _D_; 539); the number of loculi in the ovary equals that of the carpels; _only =1= pendulous (anatropous) ovule_ (Fig. 528 _C_) _in each loculus_. Endosperm copious (Fig. 528 _D_). To this must be added that the inflorescence in the majority of cases is an _umbel_ or a capitulum, especially in the _Umbelliferæ_ and _Araliaceæ_. Stipules are absent, but most frequently the base of the petiole forms a large sheath.

The Umbellifloræ are on one side so closely allied to the Frangulinæ, especially Rhamnaceæ, that they may perhaps be regarded as the epigynous continuation of this family. On the other hand, the similarities to the Rubiales, especially those between Cornaceæ and Sambuceæ, are so great that there is scarcely any character to distinguish them except the polypetalous corolla of the former and the gamopetalous corolla of the latter. Whether this is more than a merely analogous resemblance, and if not, whether the Cornaceæ at least should not be included in the Rubiales, must be left in abeyance.--The sepals are very small, as is generally the case in epigynous flowers.

Order 1. =Cornaceæ.= The majority of the species are shrubs with solid internodes, _opposite_ (rarely scattered) leaves, which are _simple_, _entire_ (rarely incised), penninerved, _without_ stipules or large sheaths; flowers _=4=-merous_ (most frequently S4, P4, A4, G2), borne in dichasia which are either collected into corymbs (_e.g._ _Cornus sanguinea_), or in closely crowded umbels or capitula (_Cornus mas_, _C. suecica_), in which latter case there is often a _large_, leafy, or coloured, most frequently 4-leaved _involucre_ round the base of the inflorescence; the _style is undivided_, with lobed stigma; the raphe of the ovule is turned _outwards_. The fruit is a _berry_ or a _drupe_, with a 1–4-locular stone or 2 free stones.

_Cornus_ (Dogwood, Cornel) has S4, P4, A4, G2. Leaves opposite.

_Drupe_ with a bilocular, 2-seeded stone.--_Aucuba_, diœcious; unilocular ovary; 1 ovule; 1-seeded berry.--_Garrya._--_Helwingia._

80 species; N. Temp. The fruits of _Cornus mas_ are edible; the wood is very hard; gum is found in some. Several species of _Cornus_ and _Aucuba japonica_ (Japan) are cultivated as ornamental shrubs.

Order 2. =Araliaceæ (Ivies).= Principally _trees_ or _shrubs_ with _solid stems_. The leaves are _scattered_, simple or compound, with a sheath more or less developed. The flowers are most frequently situated in umbels or capitula which are either borne singly or in racemes, or in paniculate inflorescences. The small, most frequently yellowish-green flowers are =5=-_merous_, in the calyx, corolla, and andrœcium; the gynœceum may be 5-merous or may have some other number (=2=-∞). The styles are most frequently several, free; the _raphe_ of the ovules is turned _inwards_ as in the Umbelliferous plants. The fruit is a _drupe_ or _berry_.--~Stellate hairs often occur. The petals generally have a broad base, and a thick apex which is slightly incurved, and a distinctly valvate æstivation.~

_Hedera helix_ (Ivy) climbs by adventitious roots. The leaves are palminerved and lobed on the sterile branches, but often ovate and not lobed on the flowering branches. ~The flowers are yellowish-green and open in the autumn; they are slightly protandrous, and are visited by flies and wasps. Berries black. Endosperm ruminate.--_Panax._ _Aralia_ (with _Dimorphanthus_).~

375 species, 51 genera; especially in the Tropics (E. Asia).--The Ivy, several species of _Aralia_, _e.g._ _A. japonica_ (_Fatsia_), _Gastonia palmata_, are cultivated as ornamental plants. Paper is manufactured from the pith of _Aralia papyrifera_ (China).

Order 3. =Umbelliferæ.= _The stem is herbaceous_ with _hollow internodes_; the leaves are _scattered_, and have a broad, amplexicaul base, a _large, most frequently inflated sheath_, and generally a pinnate (often very much dissected) blade. ~Entire leaves are found in _Hydrocotyle vulgaris_; _Bupleurum_.~

The flowers are ☿, regular, small, but collected in _compound umbels_, that is, in “simple umbels,” which again are borne in umbels (for exceptions see _Hydrocotyleæ_); the external flowers in the simple umbel have often subtending bracts, which surround the base as an _involucre_, and may be termed the _small involucre_; the internal ones have no bracts; when involucral leaves are present at the base of the compound umbel, they may be termed the _large involucre_.