Part 37

◯=: _Thlaspi_ (Penny-Cress) has a flat, almost circular silicula, emarginate or cordate, with a well-developed wing round the edge (Fig. 406). _Iberis_ and _Teesdalia_: the racemes during flowering are especially corymbose, and the most external petals of the outer flowers project radially and are much larger than the other two (the flower is _zygomorphic_).--_Biscutella_, _Megacarpæa_.

◯‖: _Capsella_ (Shepherd’s-Purse) has a wingless, obcordate or triangular silicula (Fig. 407). _Lepidium_ (Pepperwort) has a few–(2–4) seeded, slightly winged, oval silicula. _Senebiera_ has a silicula splitting longitudinally into two nut-like portions; its cotyledons are folded.--~_Anastatica hierochuntica_ (“Rose of Jericho”) is an annual, silicula-fruited, desert plant (Arabia, Syria, N. Africa). After the flowering all its then leafless branches bend together upwards, forming a kind of ball; this spreads out again on coming in contact with water, and the fruits then disseminate their seeds, which germinate very quickly, often in the fruit.~

3. =Siliqua= (Siliquosæ). The fruit is a true siliqua, several times longer than broad. The seeds in most are borne apparently in one row.

◯>>: _Brassica_ (Cabbage). The seeds are placed apparently in one row in each loculus (Fig. 398 _C_); the style is long and round; the valves have only 1 strong, longitudinal rib.--_Melanosinapis_ (_M. nigra_, Black-mustard); the style is compressed, two-edged; the valves of the siliqua are one ribbed.--_Sinapis_ (Mustard); quadrangular or flat style (in which in most cases there is a seed) and 3–5 strong, longitudinal ribs on the valves.--_Eruca_ differs from _Brassica_ by the shorter siliqua, broad, sword-like “beak” and seeds in two rows.

◯= (Fig. 399): _Cardamine_ (Bitter Cress) has a long, linear siliqua, with flat, unribbed, _elastic_ valves. The leaves are most frequently pinnatifid or pinnate. ~_C. pratensis_ reproduces by buds formed in the axils of the leaves.~--_Arabis_ (Rock Cress); _Matthiola_ (Stock); _Cheiranthus cheiri_ (Wallflower); _Barbarea_ (Winter Cress) (double-edged, quadrangular siliqua); _Nasturtium_ (_N. officinale_, Water-cress); the siliqua of the latter genus is in some species short, in others long.

◯‖ (Fig.400): _Sisymbrium_ (Hedge Mustard) the valves of the siliqua are 3-ribbed.--_Erysimum_; _Hesperis_; _Schizopetalum_ (with fimbriate petals).

4. =Fruit jointed= (Lomentaceæ). The fruit is divided by transverse walls into as many spaces as there are seeds, and dehisces at maturity, generally _transversely_, into a corresponding number of nut-like joints (“articulate-siliqua.”)

◯=: _Crambe_ (Kale, Fig. 408). The fruit has only 2 joints. The lower one resembles a short, thick stalk, and is barren, the upper one is spherical, and has 1 seed.--_Cakile_ (_C. maritima_, Sea-kale); the lower node is triangular, 1-locular, the upper one more ensiform, 1-locular (Fig. 409).

◯>>: _Raphanus_ has a long siliqua, which, in the garden Radish (_R. sativus_), is spongy and slightly abstricted (Fig. 411), but neither opens nor divides transversely (a kind of dry berry), and which in the Wild Radish (_R. raphanistrum_) (Fig. 410) is abstricted in the form of a string of pearls, and separates into many joints. ~_R. sativus_; the “Radish” is formed by the hypocotyl, after the bursting of its external, cortical portions (of which there are generally two patches at the top of the Radish).~

5. =Siliqua indehiscent= (Nucumentaceæ). The fruit is a short, _unjointed_, unilocular and 1-seeded nut, and the fruit-stalks are often long, slender, and drooping. (Sometimes a thin endosperm is present).--_Isatis_ (Woad) has most frequently an oblong, small-winged nut; ◯‖ (Figs. 412, 413).--_Bunias_; _Neslia_.

[The systematic division of this order given above is founded upon that of A. P. de Candolle. Prantl (_Engler and Prantl, Nat. Fam._), 1891, adopts a somewhat different system, which may briefly be summarised as follows:--

_A._ Hairs unbranched or absent; no glandular hairs.

1. THELYPODIEÆ. Stigma equally developed on all sides; style undivided or prolonged above the middle of the carpels, or turned back.--_Stanleyinæ_; _Heliophilinæ_.

2. SINAPEÆ. Stigma strongly developed above the placenta; style beaked or two-lobed.

_a._ Cotyledons arising behind the bend of the embryo.--_Lepidiinæ._

_b._ Cotyledons arising at the bend of the embryo.

α. Only lateral nectaries. Generally a silicula or indehiscent fruit.--_Cochleariinæ._

β. Generally a siliqua, more rarely a silicula or transversely-divided or indehiscent fruit. Nectaries generally lateral and median.--_Alliariinæ_; _Sisymbriinæ_; _Vellinæ_; _Brassicinæ_; _Cardamininæ_.

_B._ Hairs collectively or partially branched, very rarely entirely absent; glandular hairs are sometimes also present.

1. SCHIZOPETALEÆ.

2. HESPERIDEÆ. Stigma strongly developed above the placenta; style undivided or prolonged above the placentæ into shorter or longer lobes.

_a._ Surface cells of the replum, not divided diagonally.--_Capsellinæ_; _Turritinæ_; _Erysiminæ_; _Alyssinæ_.

_b._ Surface cells of the replum divided diagonally.--_Malcolmiinæ_; _Hesperidinæ_; _Moricandiinæ_.]

POLLINATION. Honey is secreted by the nectaries mentioned above; but the position of the stamens is not always the most favourable for pollination by insects (in these flowers the honey-seeking insect must touch the anthers with one of its sides and the stigma with the other), and self-fertilisation is common. In some species (_Cardamine pratensis_) the long stamens turn their anthers outwards towards the small stamens, so that 3 anthers surround each of the two large entrances to the nectaries.

1200 species (180 genera), especially in the cold and temperate parts of the Old World (Europe, W. Asia). Many are _weeds_ in this country, _e.g._ Wild Cabbage (_Brassica campestris_), Charlock (_Sinapis arvensis_), Wild Radish (_Raphanus raphanistrum_) and others.--The order is acrid and oleaginous. Oil is obtained from many of the oil-containing seeds, especially of the Rape (_Brassica napus_), Summer-Rape (the oil-yielding cultivated form of the Field-Cabbage) and _Camelina_. Several are pot-herbs or fodder plants, _e.g._ Cabbage

(_Brassica oleracea_) with its numerous varieties: Cauliflower (var. _botrytis_; the entire inflorescence is abnormally branched and fleshy), Kohlrabi (var. _gongylodes_, with swollen, tuberous stem), Kale, Red-Cabbage, White-Cabbage, etc.; _B. campestris_, var. _rapifera_ (Turnip); _B. napus_, var. _rapifera_ (Swede); _Raphanus sativus_ (Radish from W. Asia), _R. caudatus_ (long Radish); _Nasturtium officinale_ (Water Cress), _Lepidium sativum_ (Garden Cress), and _Barbarea præcox_ (Early Cress); _Crambe maritima_ (Sea-Kkale). The seeds of the following are especially used as spices: (the flour of) _Melanosinapis_ (Black-mustard), and _Sinapis alba_ (White-mustard), which are _officinal_ like the root of _Cochlearia armoracia_ (Horse-radish, E. Eur.). The herbaceous parts of _Cochlearia officinalis_ and _danica_ are medicinal.--A blue dye (woad) is extracted from _Isatis_.--Ornamental plants: _Cheiranthus cheiri_ (Wallflower), _Matthiola_ (Stock), _Iberis_, _Hesperis_, _Lunaria_, and others (especially from S. Eur.). Sweet-scented flowers are rare.

Order 4. =Capparidaceæ= (=Capers=). The relationship with the Cruciferæ is so close that certain forms are with difficulty distinguished from them. The diagram of the flower is the same in the number and position of its parts, but it differs in the modifications which occur in the development of the stamens. In some genera all 4 stamens are undivided; in others both the 2 median ones are divided as in the Cruciferæ (6 stamens, but _not tetradynamous_) (Fig. 414); in other genera only 1 of these; in other instances again they are divided into more than 2; and finally the 2 lateral ones also may be found divided, so that _indefinite stamens_ occur (Fig. 415). The bicarpellate gynœceum is _unilocular_ (without replum), but more than 2 carpels may occur. The ovary is elevated on a _stalk_ (sometimes as much as 1 foot in length); also between the stamens and corolla a similar stalk may be found (Fig. 414). The fruit is long and siliquose (_Cleome_, _Polanisia_, _Gynandropsis_), or a berry (_Capparis_). Endosperm absent. Some have zygomorphic flowers. Gamosepalous calyx and perigynous flowers also occur.--350 species; especially in the Tropics. The majority are trees and shrubs, and they differ also from the Cruciferæ in having distinct stipules present in some species.

“Capers” are the flower buds of the climbing, thorny shrub, _Capparis spinosa_ (Fig. 415), which grows in the Mediterranean.

Family 11. =Cistifloræ.=

The flowers in this family are perfect, regular (except _Resedaceæ, Violaceæ_), hypogynous, the perianth-leaves free (a few have them slightly united), æstivation most frequently imbricate; they are eucyclic in the andrœcium, and most frequently in the other parts, and generally 5-merous with S5, P5, A5 + 5, G3, but other numbers also occur; several have _indefinite stamens_, but the stamens arise (where the development is known) in _centrifugal order_ and are arranged, often very distinctly, _in bundles_; in other words, the large number of stamens is formed by the splitting of a small number (most frequently 5); a true spiral arrangement is never found. Gynœceum syncarpous, multicarpellary (_Dilleniaceæ_ and a few _Resedaceæ_ are apocarpous), most frequently the number of carpels is 3, forming a _unilocular ovary_ with _parietal placentæ_, but parallel with this, multilocular ovaries, with the ovules placed in the inner angle of the loculi, are also found, and a few genera have a free, centrally-placed placenta. The fruit is most frequently a capsule. The dehiscence is never with a “replum,” _i.e._ the persistent frame of the placenta, as in the family Rhœadinæ. One half of the orders has endosperm (_Violaceæ_, _Cistaceæ_, _Droseraceæ_, _Bixaceæ_, _Ternstrœmiaceæ_, etc.), the other has no endosperm (_Resedaceæ_, _Hypericaceæ_, _Elatinaceæ_, _Tamaricaceæ_, etc.); some have a curved, the majority a straight embryo. ~The family is scarcely quite natural; in the future the orders will probably be arranged differently.~

Order 1. =Resedaceæ (Mignonettes).=--Herbs or small shrubs with spirally-placed leaves and very small, gland-like stipules (as in Cruciferæ); the ☿, hypogynous flowers are _zygomorphic_, and arranged in racemes or spikes typically without bracteoles. The zygomorphic structure is produced by the _greater development of the posterior side of the flower_, especially the petals and the nectary (“disc,” in Fig. 416 _d_) which is situated between the petals and stamens; in general there are 5–8 free sepals and petals, the latter consisting of a large scale-like _sheath_ with a fimbriated blade (see Fig. 416); stamens numerous; carpels 6–2 united together; ovary unilocular with parietal placentæ, but _the cavity of the ovary is not closed_ at the top. In _Astrocarpus_ the gynœceum is apocarpous. The fruit is most frequently a capsule; the seeds are reniform, without endosperm, and the embryo is _curved_.

This order connects the Rhœadinæ with the Cistifloræ. It is closely allied to the Rhœadinæ by its external appearance, even by the smell and taste, the parietal placentation, structure of the seeds, the inflorescences, etc., whilst by the irregular flowers and the disc placed at the posterior side of the flower, _it is allied to Capparidaceæ_, but differs from this order in not having its characteristic number (2–4) and by the very different mode of dehiscence of the fruit, etc. It differs from the other orders of this family chiefly in the fact that the number of the perianth-leaves is not constantly 5. In _Reseda luteola_ both the calyx and corolla appear to be 4-leaved, because the posterior sepal is suppressed, and the 2 posterior petals are united. Where there are 10 stamens, they stand in 2 whorls, _i.e._ in front of the sepals and petals; if there are several, their position depends upon the splitting.--_Astrocarpus_ is remarkable for its apocarpous fruit and the position of the ovules on the _dorsal_ suture of the carpel.

The yellow, flat disc at the back of the flower serves as a nectary, the honey being protected by the lobes of the petals. If pollination by insects is not effected, then self-pollination may take place, at all events in _R. odorata_.

45 species; the majority in the Mediterranean and in Persia. _Reseda odorata_ (from Egypt) is cultivated on account of its sweet scent; _R. luteola_ (“Dyer’s Weed”) yields a yellow dye.

Order 2. =Droseraceæ (Sundews).= Herbs, chiefly living on moors or in water, and whose leaves are adapted to catch and digest small animals. With regard to the flower, they are closely allied to the Violaceæ, especially to those with regular flowers. _Drosera_ (Sundew) has a long-stalked scorpioid cyme with regular, ☿, hypogynous flowers, 5-merous as in _Viola_. S5, P5, A5, G3 (in a syncarpous gynœceum, with free, bifid styles and basal or parietally-placed ovules in the unilocular ovaries). The capsule opens also as in _Viola_, but, among other differences, the styles are free, the seeds very small, and surrounded by a loosely lying, thin shell. ~_Drosera_ has radical, long-stalked leaves with the blade (Fig. 417) covered by numerous strong glandular hairs, placed on the edge and in the middle; when small animals are caught by these hairs, the latter and the entire blade close slowly over them dissolving and absorbing all the digestible matter as nourishment.~

_Dionæa muscipula_ (Fly-trap; N. Am.) has the same appearance as _Drosera_, but the leaves are constructed as in Fig. 418. The stalk is flat and winged, the blade small, circular, with powerful, pointed teeth along the edge, and on its surface are 6 small bristles (_A_), which are very sensitive. When these are touched the blade quickly closes, folding along the midrib (_B_, _C_) and imprisoning the irritating object, the teeth round the edges fitting like the teeth of a trap. If it happens to be an insect or similar body, a digestive fluid is secreted which, like the gastric juice, dissolves the digestible portions. _Aldrovandia vesiculosa_ (Central and S. Europe) captures small aquatic animals in a similar manner; it is a floating, aquatic plant, the two halves of its leaves also close together when irritated (Fig. 419).--_Drosophyllum._

About 110 species; most of them in the temperate regions.

Orders 3 and 4. =Sarraceniaceæ and Nepenthaceæ.= These two orders are perhaps most closely allied to the Droseraceæ and agree with these, among other things, in the manner of taking nourishment. Like the Droseraceæ they absorb nitrogenous food from dissolved animal matter by means of their leaves, which are specially constructed both to catch, to retain, and to digest any small animals which may be caught. The SARRACENIACEÆ are North American marsh-plants (10 species) which have pitcher-like leaf-stalks, in the cavity of which a fluid (with properties approaching those of gastric juice) is secreted, and which bear at the apex a small, lid-like blade; these leaf-stalks are the catching and digestive organs.--_Sarracenia, Darlingtonia._

NEPENTHACEÆ has only 1 genus, _Nepenthes_ (the Pitcher-plant; about 35 species), especially found in tropical E. Asia; the majority are climbing shrubs. The leaf-stalks are twining organs, and terminate either simply in a tendril, or in addition to this, with a pitcher-shaped body (which in some species may be as much as a foot in length) on whose upper edge a lid-like structure is found (Fig. 420). In this pitcher, as among the Sarraceniaceæ, a fluid is secreted which is able to digest the animals captured (sometimes rather large) and which corresponds in some degree to the gastric juice.

Order 5. =Violaceæ (Violets).= The flowers are ☿, and generally zygomorphic, hypogynous, with S5, P5, A5, G3 (Fig. 421). The stamens are closely applied to the ovary, they have a very short filament, and at their summit generally a membranous appendage formed by the prolongation of the connective (Fig. 422 _g_). The ovary is unilocular with 3 parietal placentæ; style undivided (Fig. 422 _B_). The fruit is usually a 3-valved capsule, opening along the dorsal sutures (Fig. 423). Embryo straight; endosperm fleshy (Fig. 425).--Many are herbaceous plants (_e.g. Viola_), but in the Tropics shrubs are also found (_e.g. Ionidium_); a few are lianes; the leaves are scattered, with stipules, and involute in the bud.

_Viola._ The sepals are prolonged backwards beyond the point of insertion (appendiculate); the corolla is polypetalous, descending imbricate, and zygomorphic, its anterior petal being larger than the others and provided with a spur (Fig. 421). The 2 anterior of the 5 almost sessile stamens are provided with a spur-like nectary, which protrudes a considerable distance into the petaloid spur (Figs. 421, 422 _n_, _sp_). The style is club-like, and bears the stigma in a groove on the anterior side (Fig. 422 _st_). ~Herbs with rhizomes, or annuals; flowers solitary. _V. odorata_, _canina_, etc., have cleistogamic flowers which produce fruit in addition to the large, coloured (violet) flowers. The Pansy (_V. tricolor_) has large flowers adapted for insect-pollination, and also smaller, less conspicuous ones designed for self-pollination. The stigma, as in Fig. 422 _A_, _st_, and _B_, is situated on the anterior side of the stylar-head, immediately in front of the channel leading down to the spur (_sp_); below it is situated a valve, easily covered with pollen when the proboscis of an insect is introduced into the spur, but which closes upon its withdrawal; cross-pollination is thus secured.--The sweet-scented _V. odorata_ is visited by the honey-bee, which insures cross-pollination, and in the absence of insect visits it effects self-fertilisation by cleistogamic flowers. The conspicuous but scentless _V. tricolor_, var. _vulgaris_, is less frequently visited by insects (humble-bees). In _V. silvatica_ and _V. canina_ the pollen is carried on the head or proboscis of the honey-sucking bee.--The fruits of _V. odorata_ bury themselves slightly in the soil. In the others the fruits are raised above the ground; the 3 boat-shaped valves close together along the central line, and eject the seeds, one by one, with much violence, so that they are thrown to a great distance.~

The _Alsodeia_-group has regular or almost regular flowers. Gamopetalous corollas are found in _Paypayroleæ_. _Sauvagesieæ_ differs the most by its regular corolla, and 5–∞ free or united staminodes.

250 species; especially in the Tropics.--The _Ionidium_-species are used as ipecacuanha. A number of _Viola_-species are cultivated as garden plants, especially _V. odorata_ (sweet-scented Violet) and _V. tricolor_, which have a large number of varieties.

Order 6. =Frankeniaceæ.= A small order with doubtful relationships. Perennial herbs or shrubs; beach plants with nodose stem. Sepals united, petals free. Unilocular ovary, with 3–4 parietal placentæ. Fruit a capsule. Embryo straight, endospermous. Especially in S. Europe, Africa, on the shores of the Mediterranean and Atlantic.

Order 7. =Tamaricaceæ (Tamarisks).= To this order belong only _Tamarix_ and _Myricaria_. They are shrubs of a cypress- or heather-like appearance, as the scattered leaves are very small, sessile, scale-like or linear, adpressed, entire, and usually glaucous, and the branches are slender and whip-like. The flowers are borne in small spikes or racemes, and are small, reddish or whitish, regular, ☿, hypogynous and polypetalous; formula S5, P5, A5 + 0 (_Tamarix_, which often has stipular teeth at the base of the filaments), or A5 + 5 (_Myricaria_, in which the stamens are united at the base); the number 4 may appear instead of 5, but in either case there is usually a tricarpellate gynœceum, which is _unilocular_ and has either parietal placentæ (_Myricaria_) or a small basal placenta (_Tamarix_); 1 trifid style, or 3 styles. Capsule dehiscing along the dorsal suture, and resembling the Willows in having a unilocular ovary with numerous _woolly_ seeds; but the seed-wool in this case is borne on the chalaza, and may be attached to a long stalk.--Some _Tamarix_-species shed part of their branches in the winter.--40 species; North Temperate, on the sea-shores or steppes, especially in Asia. Ornamental shrubs: _Myricaria germanica_, and _Tamarix gallica_.