Part 32

The majority are trees or shrubs with petiolated leaves, _stipulate_; _rough hairs_ are very frequently developed upon the leaves. The flowers are very often crowded together in the inflorescence, which is rarely catkin-like. Peculiar aggregations of fruits are found in some orders. _Latex_ and tough _bast_, which is used technically, are also frequently found. Cystoliths are found in the epidermis of many species of _Ficus_, _Urtica_, and others. ~_Wind-_ or _self-pollination_ is most common, as in the Quercifloræ and Juglandifloræ.~ In ~the Urticaceæ, _Morus_ and some others, the stamens lie incurved in the bud, and when ripe straighten themselves suddenly and elastically, and thus small clouds of pollen-grains are ejected with considerable violence on to the stigmas, which are often provided with brush-like hairs (Fig. 341). The formation of honey does not take place.~

Order 1. =Ulmaceæ= (=Elms=).--Trees or shrubs without latex. Leaves simple, arranged in two rows (divergence 1/2), oblique (the inner side, nearer the axis, being the larger), strongly penninerved, dentate, hispid; stipules deciduous. In opposition to the other Nettle-like plants the flowers are often ☿ with a united cup- or saucer-like, generally 4–(5)–6-divided perianth, and a corresponding or larger number of opposite _erect_ stamens. The gynœceum has two carpels (2 stigmas), generally one loculus with one pendulous, anatropous or amphitropous ovule,[35] seldom two loculi and 2 ovules. Fruit one-seeded (nut or drupe). Embryo without endosperm.

=A.= ULMEÆ. The fruit is a _winged nut_ (Fig. 339), the embryo straight, without endosperm. Anthers extrorse.--_Ulmus_ (Elm). The flowers are situated in inflorescences which develop from the lower buds of the shoot of the preceding year. ~The lowermost bud-scales are empty, the uppermost support either solitary flowers, or small, dichasial or unipared scorpioid inflorescences. The terminal bud on the vegetative shoot quickly falls off, and the upper lateral bud continues the growth sympodially. Flowering takes place before the leaf-buds open. The flowers are wind-pollinated and have no honey. Fossil species have been found in the Oligocene.~

20 species; North Temp. (2 species in this country). Important as timber. The Cork-elm (_U. suberosa_) has a rather thick cork, which, however, is of no technical use. The bast is used as Lime-bast.

=B.= CELTIDEÆ. The fruit is a drupe, the embryo curved, with folded or rolled up cotyledons, with or without endosperm. The anthers are introrse. The flowers are borne on a shoot of the same year. _Planera_ (N. America); _Zelkova_.--About 114 species; especially N. Temp., Trop.

Order 2. =Urticaceæ= (=Nettles=).--The majority of species are herbs with simple, stipulate leaves; they have _no latex_; _stinging hairs_ abundant. The flowers (Fig. 340) are _unisexual_, generally 2-merous and arranged _in clusters_, which are united into catkin-like inflorescences. The perianth is composed very often of 4 (2 + 2) free, or in the ♀-flowers generally united, green leaves; the 4 (2 + 2) stamens are opposite the perianth-leaves, the filaments are _bent inwards_ in the bud and throw themselves elastically towards the outside. The gynœceum has _one style_ and _one stigma_ (capitate or brush-like, Fig. 341); the ovary is unilocular, with _one orthotropous_, _erect_ ovule (all other orders of this family have inverted or curved ovules). Fruit, a nut or drupe. _Endosperm present_ (in _Urtica_ very little), oily. Embryo straight. ~The STINGING HAIRS are club-shaped, very turgid, and provided with a siliceous, brittle apex, which breaks off in an oblique direction and allows the poisonous cell-sap to be forced out. In many tropical Nettles this is so strong that it may produce partial paralysis. There is no rudiment of an ovary in the ♂-flowers (Fig. 340 A). The PERIANTH in the ♀-flower differs from that of the ♂ in having the two internal leaves generally much larger and enveloping the fruit (Fig. 340 _B_); it often happens that all the perianth-leaves are united to form a gamophyllous envelope. ☿-flowers may occur among the others.--THE INFLORESCENCES among our native species are dichasia, which become transformed into unilateral scorpioid cymes by the development of the bud of the 2nd bracteole. In _Parietaria_ they are more pressed together, and the floral-leaves at the same time are also raised on their axillary shoots to just beneath the flower. As a rule, not only in this order but also in those related to it, a small vegetative branch is situated in the axil of the foliage-leaf, and this bears an inflorescence on each side at its base.~

_Urtica_ (Nettle) has opposite leaves with distinct stipules and stinging hairs. The perianth-leaves of the ♀-flower are free (Fig. 340).--_Parietaria_ (Pellitory) has scattered leaves without large stipules, and stinging hairs are absent. The ♀-perianth is 4-toothed, flask- or bell-shaped.--~_Pilea_ is a tropical genus with trimerous, zygomorphic ♀-flowers, the posterior perianth-leaf being much larger than the two others, and more or less hood shaped.--The flower of _Forskohlea_ is the most reduced; the ♂-flower has only one stamen, and the ♀-as well as the ♂-flowers have a one-sided, tongue like perianth (?). _Pouzolzia._~

WIND-POLLINATED. The pollen is shot out of the anthers, when they spring forward, and is caught by long stigmatic hairs. _Parietaria diffusa_ is protogynous (Fig. 341).

500 species; chiefly in the Tropics, although the few species which occur in Europe are represented by a much larger number of individuals.--USES. The bast of the native species _Urtica dioica_ and _urens_, of _U. cannabina_ (Siberia), etc.; of _Boehmeria nivea_ “Ramié” and “China-grass” (from Sunda Is., China), and others, is used in the manufacture of muslin.

Order 3. =Moraceæ= (=Mulberries=). Nearly all trees or shrubs, seldom herbs, generally with latex. The leaves are scattered, and not infrequently lobed. The flowers are _unisexual_ (monœcious or diœcious) and arranged in catkin- or capitulum-like, compound inflorescences. Perianth-leaves 2–6, generally 4, with an equal number of stamens opposite to them, as in the Nettles. The ovary is 1–seldom 2-locular, and has 2 stigmas (it is thus formed from 2 carpels) seldom only one style with one stigma. One ovule in each loculus, more or less curved, and _pendulous_; micropyle directed upwards. Fruit usually a drupe. The embryo is generally curved inside the _fleshy endosperm_, or it is exendospermous.

=A.= MOREÆ. The filaments are incurved in the bud. Leaves folded in the bud--_Morus_ (Mulberry) (Figs. 342–344). Monœcious. The inflorescences are catkin-like in appearance, but in reality composed of many small dichasia. The flowers are similar to those of the Nettle, but with 2 carpels: in the ♂ with perianth 2 + 2, and stamens 2 + 2 (Fig. 342), in the ♀, perianth 2 + 2, and 2 carpels in regular alternation. The small drupes are enveloped by _the perianth, which eventually becomes fleshy_, and as all the flowers on the axis very accurately fit together, the collection of fruits is formed, which we call a Mulberry (Fig. 344). The leaves are folded in the buds, and have small stipules. ~The following are allied to _Morus_:--_Maclura_, _Broussonetia_ (the Paper-mulberry tree) which has spheroid ♀ inflorescences (made up of dichasia), etc.~

_Dorstenia_ presents an interesting transitional form to the Fig in its flat, open, and, in some instances, lobed inflorescence on which the ♂ and ♀ flowers are sunk in grooves. Indications of a somewhat similar structure are found in certain Nettles, the sympodial axes of the dichasia becoming flatly expanded. The fruits are 1-seeded, but, nevertheless, spring open and eject their seeds.

=B.= ARTOCARPEÆ. Filaments straight in the bud; foliage-leaves with convolute vernation. An interpetiolar leaf-sheath (ocrea) formed in the axil of each leaf by the connate stipules, covers the younger leaves as a hood. It falls off as the leaf expands, and leaves a ring-like scar on the stem.--_Ficus_ (the Fig). The inflorescence (the so-called syconus) has a pear-shaped, fleshy, but hollow axis, on the interior surface of which the flowers are situated (Fig. 345). It is a kind of capitulum, with a hollow receptacle, whose “involucral” leaves close over the entrance to the interior; it is not, however, a simple capitulum, but a coalescence of cymose inflorescences. The edible parts are the fleshy stem-portion and perianth-leaves. The ♂-flower has a 2–6 divided perianth, 1–2 (–6) stamens; the ♀-flower has an oblique ovary. The fruits are drupes, with thin flesh.--~Many species have aerial roots, and some live as epiphytes on trees. POLLINATION, in the edible Fig, is effected by a small Gall-wasp (_Cynips psenes_ L.), which lays its eggs in the Fig, and hence carries the pollen away. Even in very ancient times it was customary to hang infected wild Figs on the branches of cultivated ones, so that the young Gall-wasps, as they emerged, could immediately effect the pollination (caprification). _Ficus carica_, and other species, have two kinds of ♀-flowers, besides the ♂-flowers. One kind has a short style and no stigmatic hairs, and it is only in the ovaries of these that the wasps lay their eggs (gall-flowers); the other kind has a long style and well-developed stigmatic-hairs, but the wasps cannot reach their ovaries--these are “seed-flowers.” There are, moreover, two kinds of plants of _Ficus carica_; ♀-plants, which have only seed-flowers, and bear the edible Figs, and ♂-plants (called “Caprificus”), which bear inedible fruits, and have ♂-flowers at the upper part of the Fig, but gall-flowers at the base. [The Caprificus, at Naples, bears three crops of inedible Figs each year, viz. _Mamme_ (April), _Profichi_ (June), _Mamnoni_ (August). The ♂-flowers are produced especially in June, the first Figs being almost entirely ♀, and the last having but few ♂-flowers. Each crop produces a new generation of Fig-wasps. The female wasp enters the Figs on the Caprificus, and lays one egg in each flower, with the result that the flower developes into a kind of gall. The mother-wasp dies within the Fig. The male wasp is wingless; it bites a small passage into the ovaries containing the female wasps, and impregnates them; the female wasps then escape from the Fig, those in the _Profichi_ carrying pollen away with them as they pass out. They then enter another Fig, lay their eggs, and die. The edible Fig-tree similarly has three crops in the year, _Fiori di fico_, _Pedagnuoli_, _Cimaruoli_. The wasps, entering these Figs, are unable to lay their eggs in the ovary, but, nevertheless, they effect cross-pollination on entering the _Pedagnuoli_, which bear fertile seeds.]~

The flowers of _Brosimum_ are the most reduced. The perianth is wanting, and the ♂-flower has only 1 stamen. _Cecropia_ (Trumpet-tree), in S. Am., has its pith divided into chambers; these are inhabited by ants, which feed upon small food-bodies formed on the swollen base of the petioles. The leaves are petiolated, often shield-like, fringed or lobed, and sometimes with white felted hairs. They serve as food for _Bradypus_ (the Sloth). _Sorocea_; _Castilloa_.

About 300 species exclusively in the warmer climates. The white Mulberry (_M. alba_, from China, India, Mongolia) is cultivated for the sake of its leaves, which are the indispensable food for silkworms. The black Mulberry (_M. nigra_, W. Asia) is cultivated for its fruits, which are used for the officinal Mulberry juice. The ordinary Fig-tree (_Ficus carica_) is from the Mediterranean. The fruit of the well-known Oriental Sycamore (_F. sycomorus_) is edible. The Bread-fruit tree (_Artocarpus incisa_) and the Jack (_A. integrifolia_) have their home in the South Sea Islands, and are cultivated in tropical countries. The Bread-fruit is morphologically the same as the Mulberry. It has a very large, spheroid inflorescence, whose floral-leaves and perianth become fleshy and united into one nutritious mass, together with the axis, which is also fleshy. The milky juice of the India-rubber tree (_Ficus elastica_, East Indies, a common house-plant), and of _Castilloa elastica_ (Am.) is the raw material of India-rubber. The milky juice of _Galactodendron utile_ (Cow-tree, S. Am.) is saccharine and nutritious, but in _Antiaris toxicaria_ (the Upas-tree, of Java) it is a strong poison. The bast of the Paper-Mulberry tree (_Br. papyrifera_, Eastern Asia); is used in Japan for paper. Shellac is obtained from a small, hemipterous insect (_Coccus lacca_), which lives upon _Ficus laccifera_ and _F. religiosa_ (the Bo-tree, sacred to Buddha), E. India. The wood of _Maclura aurantica_ (Am.) has a yellow colour, and is known as yellow Brazilian wood.

Order 4. =Cannabaceæ.= The plants which belong to this order are _aromatic herbs_, either annuals or perennials, _without latex_. Leaves _palminerved_, and more or less divided, hispid, and with free, persistent stipules. Flowers always _diœcious_; ♂-flowers in panicles, formed of dichasia, passing over into uniparous scorpioid cymes. They differ from the Nettles, particularly in the 5-leaved perianth of the ♂-flower, the 5 stamens (Fig. 346–351) with filaments _erect_ in the bud, and in the ♀-flower by the small, entire, cup-like perianth, which surrounds the base of the ovary (Fig. 346, p. 352). The ovary has two styles, or one divided into two, with two stigmas and a pendulous, curved ovule (Fig. 346 _B_, 352 _B_); the fruit is a nut; the _embryo_ is _curved_ (Hemp, Fig. 353), or rolled (Hop, Fig. 349), _without endosperm_.

Only 2 genera with 3 species (Asiatic), of which two are cultivated.--_Humulus lupulus_ (Hop, Figs. 347–349) is a twining, perennial plant, twisting to the right, with opposite, palmilobed, rough leaves, and large, interpetiolar stipules. The ♀-flowers are situated in closely-flowered, cone-like, compound inflorescences, with ultimately large, thin, imbricate floral-leaves (Fig. 348) which bear the yellow, glandular hairs, containing lupulin. ~This inflorescence is made up as follows:--The most external floral-leaves are situated in pairs, and are the persistent stipules of a leaf, the blade of which has become suppressed, or in any case is rudimentary. Such a pair of stipules supports 4 (2–6) flowers in a double uniparous cyme, whose central axis does not develope into a flower. The bracts of these flowers (bracteoles of the partial inflorescence) become, at maturity, very large, spathe-like, and, together with the stipules, produce a cone-like appearance.~

_Cannabis sativa_ (Hemp, Figs. 350–353) is an East Indian herb, with palmilobed leaves, and differs from the Hop in being annual, erect, and in having its leaves opposite at the base and scattered above. The ♀-inflorescence is not cone-like as in the Hop, but the flowers are similar in construction. ~The main difference is to be found in the axillary shoot, which was suppressed in the Hop, and is in the Hemp developed into a leaf-bearing shoot which on each side bears only one ♀-flower, and in the fact that the bracts are not so strongly developed.~

The “Hops” (the female inflorescences) are used in brewing, and medicinally on account of the yellow glands which contain lupulin. The Indian variety of _Cannabis sativa_ contains an abundance of glandular hairs and resin. The withered inflorescences are used in medicine and are officinal. The bast of the stems of the Hemp is also used and the fat oil of the seeds. In Oriental countries the entire plant is used in the preparation of an intoxicating drink (haschisch), the narcotic material being found in the glandular hairs.

Family 6. =Polygonifloræ.=

This family is on one side closely allied to the _Urticaceæ_ by its solitary, _basal_, _vertical_, and _straight_ ovule, and by the conical ocrea which envelopes the younger leaves in the bud, similar characters being present in the Urticaceæ. On the other side it is related to the Curvembryæ. The flowers are small, often _trimerous_, regular and slightly perigynous (~in _Chloranthaceæ_, if they properly belong to this family, and _Houttuynia_, more or less epigynous~). Syncarps are present in some Piperaceæ, but the fruit is generally a single fruit, one-seeded berry, nut or drupe. The leaves are generally scattered.

Order 1. =Polygonaceæ.= The majority are herbaceous plants with round, often jointed stems, scattered leaves and _ocrea_, that is a membranous, tubular, ligular or stipular structure _inside_ the base of the leaf, which clasps the stem and axillary bud; the edges of the lamina are rolled backwards in the bud. The flowers are regular, small, generally ☿, slightly perigynous, with inconspicuous, simple, green or white perianth of 5–6 free segments; stamens 5–9 (Fig. 354) sometimes arranged in two series; gynœceum 2–3 carpels, ovary _unilocular_ with _one basal_, _straight_ (orthotropous) _ovule_, 2–3 _free styles_. The fruit is a 2–3-angular nut; the embryo, with mealy endosperm, is straight or curved (Fig. 355 _H_), often unsymmetrical.--~The inflorescences are compound, and generally branch from the axils of the bracteoles, so that the last partial-inflorescences become coiled, uniparous scorpioid cymes; in _Polygonum_ the two bracteoles unite into a membranous tube; in _Rheum_ and _Rumex_ there is only one bracteole.~

_Rheum_ (Rhubarb, Fig. 354 _A_) has a 6-leaved, _petaloid_ perianth (Pn 3 + 3) and 9 stamens (A 3^2 + 3). The _3-winged_ nut is _not_ enclosed by the perianth.

_Rumex_ (Dock, Fig. 354 _B_) has 6 stamens (A 3^2 + 0); the perianth is 6-leaved (Pr 3 + 3), green or red, and the triangular nut is enveloped by the 3 interior perianth-leaves, which point upwards and continue to grow after flowering. These perianth-leaves often have warts on their outer surface. ~The following are monœcious: _R. acetosa_ and _R. acetosella_.~

_Polygonum_ (Knot-grass, Figs. 354 _C_, _D_; 355). The _petaloid_ perianth is most frequently 5-merous (2/5 spiral); 5–8 stamens. The nut is triangular (Fig. 354 _C_, 355), or lenticular (Fig. 354 _D_). ~There are two whorls of stamens, the external with introrse, and the internal with extrorse anthers. The gynœceum is often bicarpellate (Fig. 354 _D_).~

The flowers may be considered as constructed upon the monocotyledonous type. _Pterostegia_ has a perfectly monocotyledonous flower with 5 trimerous whorls. _Rheum_ likewise, but here the external staminal whorl is doubled (Fig. 254 _A_). _Oxyria_ has a dimerous _Rheum_-flower (4-leaved perianth, 6 stamens, 2 stigmas). _Rumex_ has a _Rheum_-flower with the suppression of the internal whorl of stamens (Fig. 354 _B_); _Emex_ is a dimerous _Rumex_. _Polygonum_, to which _Coccoloba_, _Muehlenbeckia_ and others are related, differs from _Rheum_ chiefly in having one of the leaves, which in the latter takes part in the formation of the perianth, developed in this case into a bracteole (so that the perianth is reduced to five members), and several or all the stamens in the inner whorl become suppressed.--The perianth in _Coccoloba_ and _Muehlenbeckia_ is more or less perigynous and becomes fleshy, enclosing the fruit. _Muehlenbeckia platyclada_ has flat branches with rudimentary leaves; sometimes branches with normal, arrow-shaped leaves are found. _Atraphaxis._

POLLINATION. _Rumex_ is wind-pollinated, the stigmas are therefore large and brush-like (indicated in Fig. 354 _B_). _Rheum_ and _Polygonum_ are insect-pollinated and have therefore capitate stigmas, etc.; honey-glands are situated at the base of the stamens (_d_, in Fig. 354 _C_, and _n_ in Fig. 356); a few small-flowered _Polygonum_ species are self-pollinated; Buckwheat (_P. fagopyrum_) is dimorphic and has long-styled and short-styled flowers (Fig. 356). _Pol. bistorta_ is protandrous and homostyled.

About 750 species, most of which are found in the temperate regions of the Northern Hemisphere, some reaching as far as the snow line or into the Arctic regions (_Oxyria_, _Kœnigia_). Trees and shrubs are found in the Tropics: _Coccoloba_, _Triplaris_. _Rheum_ is Central Asiatic.--The thick rhizomes of _R. officinale_ (_Rhubarb_) are _officinal_. The rhizomes of the ordinarily cultivated species, _R. undulatum_ and _rhaponticum_, are used in veterinary medicine. The following are cultivated as culinary plants for the sake of their leaves:--_Rumex acetosa_ (Sorrel), _R. patientia_, _R. scutatus_, and _Rheum undulatum_ (petioles). Several species of _Polygonum_ (_P. hydropiper_ and others) have a sharp, pungent taste. “Buckwheat” is the mealy fruit of _Polygonum fagopyrum_ (Central Asia) and is of value as a farinaceous food. _P. cuspidatum_ (_P. sieboldi_, Japan) is an ornamental plant.--_Calligonum_ in sandy and stony deserts.