Part 38

Order 8. =Cistaceæ.= Shrubs or herbs, natives especially of the Mediterranean region. Flowers generally in raceme-like scorpioid cymes, regular, ☿, hypogynous; sepals 5, free, _twisted_ in the bud, of which the two outer are generally much smaller than the others; petals 5, free, _twisted_ in the bud (in the direction _opposite_ to the sepals), fugacious; stamens _numerous_; gynœceum syncarpous, carpels usually 3–5, style simple, ovary unilocular, with parietal placentation (seldom divided into loculi, with axile placentation). The ovules are _orthotropous_ in opposition to some of the other orders of this family. The capsule dehisces along the dorsal sutures; embyro _curved_. The leaves are simple, undivided, generally opposite and stipulate.--~They are Violaceæ with regular flowers, numerous stamens, and curved embryo. The numerous stamens are in reality only one or two 5-merous whorls, divided into a large number of stamens; these are formed, therefore, in descending order, like the lobes of many compound foliage-leaves.~

_Helianthemum_ (Rock-Rose), has 3 carpels.--_Cistus_ has 5 (-10) carpels.

About 70 species; temperate climates, especially about the Mediterranean. The resin of the _Cistus_-species has been used medicinally (ladanum).

Order 9. =Bixaceæ.= This order is closely allied to the Cistaceæ and Ternstrœmiaceæ; like these it has regular, 5-merous, hypogynous flowers with numerous stamens, unilocular ovary and _parietal_ placentæ; sometimes unisexual flowers; it differs in having anatropous ovules, in the æstivation of the sepals, etc. All species (about 180) are trees or shrubs, with scattered, simple leaves, which usually have stipules, and are occasionally dotted with pellucid oil-glands.--_Bixa orellana_ (Trop. Am.) is the best known species; it has a 2-valved capsule; the seeds are enclosed in a shiny _red, fleshy testa_, which contains the well-known orange or yellow dye, annatto.

Order 10. =Dilleniaceæ.= Gynœceum usually apocarpous, seed arillate. The flower has most frequently S5, P5, and compound stamens (one or more bundles); sometimes irregular. 200 species; Tropical; woody plants, many lianes.--_Dillenia_, _Candollea_, _Pleurandra_, _Davilla_, etc.

Order 11. =Elatinaceæ= (=Water-worts=). About 25 species belong to this order; especially in temperate climates. They are small, creeping, rooted, aquatic plants, with opposite or verticillate leaves and _stipules_. The flowers are solitary or situated in small dichasia in the leaf-axils, they are small, regular, ☿, hypogynous, with free petals, the same number in all 5 whorls (Sn, Pn, An + n, Gn), 3-merous (_e.g. Elatine hexandra_), 4-merous (_e.g. E. hydropiper_), or 5-merous (_Bergia_); the corolla-stamens are sometimes suppressed; petals imbricate without being twisted; the ovary is 3–4–5-locular, with 3–4–5 _free styles_; the capsule dehisces septicidally. The seeds are orthotropous or curved, often transversely ribbed, endosperm wanting. The order is most nearly allied to Hypericaceæ, whose primitive form it appears to represent.

Order 12. =Hypericaceæ= (=St. John’s-worts=). This order is recognised by its always _opposite_ or _verticillate_, _simple_, and entire, penninerved leaves, without stipules, and usually dotted with _pellucid_ glands; by the always ☿, regular, hypogynous flowers in a cymose inflorescence; the generally 5-merous calyx and corolla, with sepals and petals free; the stamens 3–5, numerously branched (Figs. 426, 427); and the gynœceum, 3–5-carpellate, styles usually _free_. The ovary is 3–5-locular, or unilocular with 3–5 parietal placentæ. Fruit a capsule (dehiscing septicidally) or berry. Endosperm absent.

The inflorescence is a _dichasium_ or _helicoid cyme_. The structure of the flowers is the same as that of the foregoing orders: S5, P5; succeeding these in some cases are two 5-merous whorls of stamens in regular alternation, of which the inner is epipetalous; but the outer whorl is only represented by 5 small scales (Fig. 427), or is altogether absent (_Hypericum calycinum_, _H. hircinum_), and the inner divided into numerous stamens, that is, these 5 stamens are so deeply divided that 5 _epipetalous_ groups bearing anthers are found (as in the Cistaceæ); in other cases the flower becomes _3-merous after the petals_, stamens 3 + 3 following in regular alternation (Figs. 426, 427), the outer whorl of stamens in these cases is also present as staminodes (Fig. 427), or may be altogether suppressed. Carpels 3–5. _The petals are often twisted_ in the bud, and are then oblique.

_Hypericum._ Some species have a square stem; in these cases the leaves are placed opposite the edges. Fruit a capsule.--_Vismia_ has a berry.--~The flowers of _Hypericum_ have no honey, and supply only pollen; self-pollination often takes place.~

About 240 species; the tropical ones being often shrubs or trees; the others generally perennial shrubs.--_Hypericum_, St. John’s-wort, contains a resinous, red matter, which can be extracted with alcohol. The American gamboge is the dried sap of species of _Vismia_.

Order 13. =Guttiferæ=, or =Clusiaceæ=. Closely allied to the Hypericaceæ and Ternstrœmiaceæ. Leaves opposite or verticillate. The flowers are often unisexual; stamens united; the gynœceum has most frequently a sessile, radiating or shield-like stigma.

370 species; chiefly in the Tropics (Am.). They are principally woody plants and their bark contains a yellow gum resin, “gamboge,” which is extracted from _Garcinia morella_ (E. Ind.) and others. Mangosteen (_Garcinia mangostana_ S.E. Asia), and _Mammea americana_ (W. Ind.), have very delicious fruits. To this order also belong _Platonia insignis_, _Pentadesma butyracea_ (the Butter-tree), _Clusia_, _Calophyllum_, _Cataba_, etc.

Order 14. =Ternstrœmiaceæ.= Trees and shrubs with scattered, simple, and often more or less leathery, evergreen, penninerved leaves, without stipules (Fig. 428). The two most important genera are: _Camellia_ and the closely allied _Thea_ (by some authorities these are united into one genus). The flowers are regular, hypogynous, and situated singly on very short stalks. A number of green floral-leaves are placed below the calyx and gradually pass over into the sepals, and the leaves (5–6) of the calyx again gradually pass over into the corolla (this being especially marked in _Camellia_), of which the number of leaves varies (5, 6, 7 and upwards); the calyx and the corolla are _acyclic_ or _eucyclic_; the petals are slightly united at the base; stamens _numerous_ in many whorls, the external ones are arranged in bundles and united with the petals as in the Columniferæ; gynœceum syncarpous; styles often _free_ nearly to the base; ovary 3–5-locular, ovules numerous in each loculus. The fruit is a woody capsule.--~Other genera show more distinctly than these the same structure as in the preceding orders, namely: S5, P5, A5 + 5, of which the calyx-stamens are often suppressed, and the petal-stamens divided into numerous stamens.--_Kielmeyera_ (S. Am.)~

260 species; especially in the Tropics (E. Asia, Am.) The leaves of _Thea chinensis_ (or _Camellia thea_), the Tea-tree (E. Asia), are cultivated for the well-known “tea,” and contain theine: the best are the young, still hairy leaves, of greyish colour; there are many varieties. Ornamental plants, _Camellia japonica_ and _Actinidia_.

Closely allied to this order are: Order 15. =Rhizoboleæ= (with enormously large hypocotyl--hence the name), and Order 16. =Marcgraviaceæ= (partly epiphytes, with dimorphic leaves and cup- or helmet-like, coloured, honey-secreting floral-leaves, which serve to attract insects).

Order 17. =Dipterocarpaceæ.= This order has taken its name from the large wings attached to the fruits in _Dipterocarpus_ (the wings being largely developed sepals); trees and shrubs from Trop. Asia. 180 species. Camphor ready prepared is found in the stem of _Dryobalanops camphora_. _Hopea_; _Vateria_.

Family 12. =Gruinales.=

The flowers are hypogynous, ☿, polypetalous, usually regular (except _Pelargonium_, _Tropæolaceæ_, _Balsaminaceæ_) and _throughout 5-merous_: S5, P5, A5 + 5, or 5 + 0, G5 (_epipetalous_). The stamens soon fall off and are _obdiplostemonous_, often united at the base (_monadelphous_); the corolla-stamens are in some completely suppressed (_e.g. Balsaminaceæ_, Fig. 438), in others reduced to teeth (_Linum_, Fig. 431; _Erodium_). The _Tropæolaceæ_ have 3 carpels and only 8 stamens (Fig. 437). Ring-like nectaries are not present, but at most only glandular bodies, borne outside the base of the stamens. Ovaries many-locular. The ovules as a rule are pendulous, with the micropyle directed outwards (Fig. 431, B), and the radicle therefore also points outwards. Usually _herbs_. Related to the Columniferæ.

Order 1. =Oxalidaceæ.= Most of the species are herbs with rhizomes; the leaves are stalked, _compound_, with entire leaflets which are folded and bent backwards in the bud (and in the sleep position), exstipulate; some species have sensitive leaves. The flowers (Fig. 429) are regular, and have S5, P5, which are _twisted_ to the left or right in æstivation, A5 + 5, all united at the base (monadelphous), gynœceum 5-carpellate, _styles 5 free_, stigmas capitate, ovary 5-locular, ovules numerous. The fruit is a _capsule opening_ with clefts _on the dorsal sutures_ through which the seeds are ejected, while the _fleshy, external layer of the testa_ springs off elastically. Embryo straight. Endosperm.

_Oxalis_ (Wood-Sorrel). Leaves digitate. Species also occur with phyllodia, _i.e._ leaf-like petioles placed vertically without lamina; a few have pinnate leaves. The flowers are situated singly or in dichasia, and unipared scorpioid cymes. The pollination is effected by insects. Some species are trimorphic (long-, short-, medium-styled flowers) and some, _e.g. O. acetosella_, have cleistogamic flowers in addition to the ordinary ones. Glands are found on the outer side of the corolla-stamens or of all the stamens. _O. tetraphylla_ and others have adventitious edible roots, resembling tap-roots.--_Averrhoa_ is a tropical tree, with berries and pinnate leaves.

235 species (205 belong to _Oxalis_); chiefly in S. Africa and Trop. America.--Oxalate of potash is contained in the leaves of _Oxalis_.

Order 2. =Linaceæ.= Herbs with scattered or opposite, sessile, _simple_, small, entire leaves, without (rarely with small) stipules. The flowers (Fig. 430) are regular, 5- or 4-merous. Petals are free, _twisted_, quickly falling off. Stamens united at the base; the petal-stamens _are either reduced to teeth_ (Fig. 431 _A_, _m_) _or entirely suppressed_. _Styles free._ The (5–4) epipetalous loculi of the ovary are incompletely halved by _false divisional walls_, each half contains one ovule (Fig. 431 _C_). The fruit is a spherical _capsule, dehiscing along the divisional wall_ (Fig. 432); the 10 (-8) seeds have a straight embryo and very slight endosperm (Fig. 433).

_Linum_ (Flax) has 5-merous flowers. ~The main axis terminates in a flower; and the succeeding branching is cymose, or unipared scorpioid branching by unilateral development, and the flowers in consequence of the vigorous sympodial development of the lateral axis (and also by the leaves being displaced and pushed aside), assume a position apparently lateral (_i.e._ racemose) without bracts; each branch of the sympodium generally has 2 leaves. The testa is shining and smooth when dry, but its external cellular layer becomes mucilaginous in water.~--_Radiola_ has a 4-merous flower. It is a small herb with opposite leaves, and regular, dichasial branching.

The anthers and stigmas in _L. catharticum_ and _usitatissimum_ develop simultaneously, and cross-pollination as well as self-pollination takes place. _L. grandiflorum_, _perenne_, and others, are dimorphic (short-and long-styled). There are 5 nectaries outside the stamens.

130 species; _Linum_ and _Radiola_ are native genera.--_L. usitatissimum_ is extensively cultivated in Europe (especially in Russia and Belgium), N. America and elsewhere (its home no doubt being Asia), partly on account of the oil (linseed oil) which is extracted from the seeds, and partly on account of the bast of the stem, which has very thick-walled cells. The seeds and oil are OFFICINAL. The species cultivated in ancient times was _L. angustifolium_. Several species are cultivated as ornamental plants.

Order 3. =Geraniaceæ.= The majority are herbs with dichasial branching, and scattered or opposite, stalked, _palminerved_ (rarely penninerved) leaves with small _stipules_. The flowers are regular (except _Pelargonium_) and 5-merous, with 10 or 5 stamens, which are slightly united at the base. Nectaries alternate with the corolla-stamens. The ovary is most frequently 5-locular, deeply 5-grooved, and bears 1 _well developed style_ (“beak”), which towards the apex divides into 5 branches bearing stigmas; ovules 1 in each loculus, pendulous or ascending. _The 5 carpels become detached from one another when ripe_, and bend or _roll back_ (Fig. 434) or become _spirally twisted_ in the upper “beak-like” part (Figs. 435, 436), whilst a _central column_ (septal column) persists; each carpel, in consequence, remains either closed, and the fruit is a 5-merous _schizocarp_ whose nut-like lower portion, containing the seed, is forced into the ground, thus burying the seed by the movements of the spirally-twisted, hygroscopic “beak” (Figs. 435, 436); or it opens along the ventral suture, so that the seeds may fall out, and it is then a 5-valved _capsule_, with septicidal dehiscence (Fig. 434) and the rolling up often takes place so suddenly and violently that the seeds are shot out to considerable distances. The embryo is usually green and _curved_, and the _cotyledons are folded_; endosperm is wanting.

_Geranium_ (Crane’s-bill) has 5 + 5 stamens,and a septicidal capsule; the carpels most frequently remain suspended from the apex of the column (Fig. 434). The leaves are most frequently palminerved. The flowers are situated solitarily or 2 together (2-flowered scorpioid cyme).--_Erodium_ (Stork’s-bill); inflorescence a many-flowered unipared scorpioid cyme, stamens 5 + 0 (petal-stamens are wanting), and fruit a schizocarp whose carpels become detached; their beaks are hairy on the internal surface and _twist themselves spirally_ (Fig. 436). The umbellate inflorescences are composed of multiflowered scorpioid cymes. The leaves are often penninerved.--~The most primitive type is represented by _Biebersteinia_: S5, P5, A5 + 5, G5 (ovaries _free_, and styles united above); fruit 5 small nuts. The most advanced type is _Pelargonium_, which has _zygomorphic_ flowers, the posterior sepal being prolonged into a spur which becomes adnate to the peduncle; the petals are unequal in size; some of the petal-stamens are often wanting. (_Erodium_ may be slightly zygomorphic).~

POLLINATION. The large-flowered _Geranium_-species are protandrous, _e.g. G. pratense_ (one whorl of stamens opens first, and then the other, and succeeding these the stigmas, after shedding the pollen the stamens bend outwards); the small-flowered are also adapted, with various modifications, for self-pollination.--470 species; moderately hot climates, especially S. Africa.--Several _Pelargonium_-species, with numerous varieties, are ornamental plants (from S. Africa).

Order 4. =Tropæolaceæ.= Herbaceous, juicy plants which have scattered, long-stalked, peltate leaves without stipules, and often climb by their sensitive petioles. The flowers are situated singly in the axils of the foliage-leaves on long stalks, and are _zygomorphic_, the receptacle under the posterior sepal being prolonged _into a spur_; there are also differences between the posterior and anterior petals, the 2 posterior petals situated on the border of the spur being _perigynous_, and the edge of the anterior petals adjoining the claw fringed. After the 5 sepals (which are more or less coloured) and the 5 petals, follow 8 _stamens_ (as the 2 median ones are suppressed, one from each whorl) and a gynœceum formed of 3 carpels; in each of the 3 loculi of the 3-grooved ovary is 1 ovule. The fruit is a _schizocarp_ and divides into 3 1-seeded, _drupe-like_ fruitlets, which do not (as in the Geraniaceæ) leave any pronounced column between them. Endosperm is wanting. The cotyledons are thick and sometimes slightly coalescent. ~Tubers often occur.~

_Tropæolum._--About 40 species; all from America.

POLLINATION.--The spur is the receptacle for the nectar; the flowers are protandrous; the anthers open first, and one by one take up a position in front of the entrance to the spur, resuming their original position when the pollen is shed; the stigma finally takes their place after the filaments have bent backwards.--These plants have an acrid taste (hence the name “Nasturtium,” “Indian Cress”), on which account the flower-buds and young fruits of _T. majus_ are used as capers. Some species are ornamental plants.

Order 5. =Balsaminaceæ.= Herbaceous, chiefly annual plants with juicy, brittle stems, so transparent that the vascular bundles may be distinctly seen. The leaves are simple, usually scattered, penninerved and dentate; stipules are wanting, but sometimes large glands are present in their place at the base of the petioles. The flowers are strongly zygomorphic; of their five 5-merous whorls the petal-stamens are suppressed (S5, P5, A5 + 0, G5); the sepals are _coloured_, the 2 _anterior ones_ (Fig. 438 _3_, _5_) _are very small_ or entirely suppressed, _the posterior one_ is very large and _elongated into a spur_, and the 2 lateral ones pushed forward; sometimes the weight of the spur turns the flower completely round, so that the posterior leaves assume an anterior position; apparently only 3 petals, since the lateral and the posterior petals become united in pairs, and the anterior is larger and differently shaped; the 5 stamens have very short and thick filaments united at the base, and their anthers finally adhere together and remain in this condition, covering over the gynœceum; the filaments ultimately rupture at the base, and the entire anthers are raised on the apex of the gynœceum as it grows up. The gynœceum has a _sessile stigma_ and a 5-locular ovary. The fruit is a capsule which, on maturity, opens suddenly when irritated, dividing into valves from the base upwards, and as the 5 valves roll up elastically, the seeds are shot out on all sides to considerable distances; a central column persists (Fig. 439). The embryo is straight, and without endosperm.

_Impatiens_; in Europe only _I. noli-me-tangere_. 225 species; especially from Asia. Several species have two kinds of flowers: small, cleistogamic, but fertile; and large, coloured flowers, which in _I. balsamine_ (ornamental plant, E. Ind.) are protandrous and pollinated by hive-and humble-bees, as they suck the honey from the spur.

Order 6. =Limnanthaceæ.= The flowers are regular and differ from all the other orders in the family by having the carpels not in front of the petals, but _in front of the sepals_ (which are _valvate_), and further, the loculi are nearly _free individually_, but with a _common gynobasic_ style; the ovules are _ascending_ and _apotropous_ (anatropous with ventral raphe). The fruit is a schizocarp, with nut-like cocci.--_Limnanthes_ (4 species; N. Am.) perhaps belongs to another family.

Order 7. =Humiriaceæ.= Trees and shrubs; about 20 species; Trop. Am.

Family 13. =Columniferæ.=

The chief characteristics of the orders belonging to this family are the ☿, regular, generally 5-merous, _hypogynous_ flowers with 5-merous _calyx_, sepals united and _valvate_ in the bud; petals 5, free (often _twisted_ in the bud); stamens ∞ _e.g._: 10, in two whorls, but one of these is more or less suppressed, often altogether wanting, or replaced by 5 staminodes, while _the other_ (inner whorl) _is generally divided more or less deeply_ into a large number of anther-bearing filaments. The filaments too (except _Tiliaceæ_) are _united into a tube_, which, especially in the _Malvaceæ_, forms a long column in the centre of the flower, surrounding the gynœceum (Figs. 445, 448); in this case, which is the most pronounced, the filaments are united into one bundle (_monadelphous_), in other instances, _polyadelphous_. The number of carpels varies greatly (2 to about 50), but they are nearly always united and form a syncarpous multilocular gynœceum.--The vegetative characters also closely agree, the leaves _are always scattered and generally stipulate_; all the green portions very often bear _stellate hairs_, and the bark in all the 3 orders is _rich in tough bast_. Mucilage is often present in cells or passages.--This family is connected with the _Ternstrœmiaceæ_, from which it is very hard to draw a sharp line of demarcation, and it is also allied to the _Cistaceæ_ and to the _Gruinales_.

Order 1. =Sterculiaceæ= (including Buettneriaceæ). This is, no doubt, the least modified order, and one in which the stamens occur undivided. Obdiplostemonous. The 10 stamens in two whorls are most frequently united at the base into a short tube, and have _4-locular, extrorse_ anthers. The calyx-stamens are nearly always simple, tooth-like staminodes, situated on the edge of the tube, or are entirely suppressed. The same relation is found, for instance, in the Ampelidaceæ and Rhamnaceæ, namely _5 stamens in front of the 5 petals_; not infrequently the 5 stamens are doubled (Fig. 441). Unisexual flowers are found in _Sterculia_, _Cola_, _Heritiera_. The corolla is often wanting, or developed in an unusual manner. Each loculus of the ovary (generally 5) always contains more than one ovule. Fruit a capsule. Androgynophore often present (_Helicteres_; _Sterculia_, etc.).