Part 59

Order 2. =Fumariacæ= (=Fumitories=). This order differs from the closely allied Papaveraceæ in the absence of latex, a poorer flower, generally transversely zygomorphic (Fig. 393 B), in which case one or both of the outer lateral petals are gibbous, or prolonged into a spur; the stamens are especially anomalous. Sepals =2=, caducous; petals 2 + 2; stamens 2, tripartite; each lateral anther is bilocular (Figs. 393 A, B; 395); gynœceum bicarpellate. The fruit is a nut or siliqua-like capsule. Endosperm.--Herbs with scattered, repeatedly pinnately-divided leaves without stipules, generally quite glabrous and glaucous; the flowers are arranged in racemes with subtending bracts, but the bracteoles are sometimes suppressed.

Dicentra (syn. Dielytra) and Adlumia have a doubly symmetrical flower, with a spur or gibbous swelling at the base of each of the laterally-placed petals (Figs. 393 A, 394). Corydalis has a zygomorphic flower, only one of the lateral petals having a spur, and consequently there is only one nectary at the base of the bundle of stamens, which stands right in front of the spur (Fig. 393 B, 395, 396). The fruit is a many-seeded siliqua-like capsule. ~A peculiarity of the flower is that the plane of symmetry passes transversely through the flowers, whilst in nearly all other zygomorphic flowers it lies in the median line. Moreover, the flower is turned, so that the plane of symmetry ultimately becomes nearly vertical, and the spur is directed backwards.--Many species have subterranean tubers; in these the embryo germinates with one cotyledon, which is lanceolate and resembles a foliage-leaf. The tuber is in some the swollen hypocotyl (C. cava), in others a swollen root (C. fabacea, etc.), which grows down through the precisely similar swollen root of the mother-plant. The sub-genus Ceratocapnos has dimorphic fruits (nuts and capsules) in the same raceme.~ Fumaria differs from Corydalis only by its almost drupaceous, one-seeded nut (Fig. 395).

THE STRUCTURE OF THE FLOWER. Hypecoum among the Papaveraceæ is the connecting link with the Fumariaceæ. The diagram (Fig. 393 C) corresponds both in number and in the relative position of its members with that of most of the other Papaveraceæ (Fig. 391), except that there are only four stamens (with extrorse anthers). In Dicentra (Fig. 393 A), the two central (uppermost) stamens are absent, but each of the two lateral ones are divided into three filaments, of which the central one bears a four-locular anther, and each of the others a two-locular (half) anther. Corydalis and Fumaria stand alone in the symmetry of the flower, differing from Dicentra in having only one of the lateral petals (Fig. 393 B, sp) prolonged into a spur, while in Dicentra both the petals are spurred. This structure has been interpreted in various ways. According to Asa Gray the median stamens are absent in the last-named genera, and the lateral ones are split in a similar manner to the petals of Hypecoum. Another, and no doubt the most reasonable theory (adduced by De Candolle), is: that two median stamens are split, the two parts move laterally, each to their respective sides and become united with the two lateral stamens; this affords a natural explanation of the two half-anthers, and establishes a close relationship to the Cruciferæ. A third interpretation, held by Eichler and others, is as follows: the median stamens are always wanting; when they appear to be present, as in Hypecoum, it is due to the fact that the side portions of the lateral stamens approach each other (as interpetiolar stipules) and coalesce into an apparently single stamen.

130 species; mostly from the northern temperatures.

POLLINATION. Fumaria, with its inconspicuous flowers, has to a great extent to resort to self-pollination. Corydalis, on the other hand, is dependent on cross-pollination; C. cava is even absolutely sterile with its own pollen. Corydalis is pollinated by insects with long probosces (humble-bees, bees), which are able to reach the honey secreted in the spur; as they alight on the flowers they press the exterior petals on one side (Fig. 396 e), so that the stigma, surrounded by the anthers, projects forward; the proboscis is introduced in the direction of the arrow in the figure, and during this act the under-surface of the insect is covered with pollen, which is transferred by similar movements to the stigma of another (older) flower.--Ornamental plants; Dicentra (spectabilis and eximia), Adlumia, Corydalis.

Order 3. =Cruciferæ (Crucifers).= The flowers are regular, ☿; sepals 4, free (2 + 2), deciduous; petals 4, free, deciduous, unguiculate, placed diagonally in one whorl, and alternating with the sepals; stamens 6; the 2 outer are short, the 4 inner (in reality the two median split to the base) longer, placed in pairs (tetradynamia of Linnæus); gynœceum syncarpous formed by 2 (as in the previous order, lateral) carpels, with 2 parietal placentæ, but divided into two loculi by a spurious membranous dissepiment (replum) (Fig. 397). Style single, with a capitate, usually two-lobed stigma, generally commisural, that is, placed above the parietal placentæ (Fig. 397), but it may also be placed above the dorsal suture, or remain undivided. Ovules curved. The fruit is generally a bivalvular siliqua (Fig. 398 B, C), the valves separating from below upwards, and leaving the placentæ attached to the replum; other forms of fruits are described below. The oily seeds have no endosperm (endosperm is present in the two previous orders); the embryo is curved (Figs. 398 E, F; 399, 400).--In general they are herbaceous plants, without latex, with scattered, penninerved leaves, without stipules; the inflorescence is very characteristic, namely, a raceme with the flowers aggregated together at the time of flowering into a corymb, and destitute of both bracts and bracteoles.

Many are biennial, forming in the first year a close leaf-rosette. By cultivation the tap-root can readily be induced to swell out into the form of a tuber (Turnips, Swedes, etc.). Stipules are found indicated by small glands on the very young leaves; in Cochlearia armoracia they are fairly large triangular scales. Stellate hairs often occur. Floral-leaves are occasionally developed. Terminal flowers are never found in the inflorescences. Iberis and Teesdalia have zygomorphic flowers. Subularia (Fig. 403) is perigynous. The 2 external sepals (Fig. 397) stand in the median plane; it may therefore be supposed that there are two bracteoles outside these which, however, are suppressed, and can only in a few instances be traced in the young flower; the two lateral sepals are often gibbous at the base, and serve as reservoirs for the nectar secreted by the glands placed above them; they correspond in position to the external petals of the Fumariaceæ. The 4 petals which follow next arise simultaneously, and alternate with the 4 sepals; if it could be shown that these are merely 2 median petals, which have been deeply cleft and the two parts separated from each other and displaced to the diagonal position, there would be a perfect correspondence with the Fumariaceous flower; then the petals would be followed in regular alternation by the 2 lateral small stamens, the 2 median long stamens, which it has been proved are split into 4 and placed in couples, and the 2 laterally-placed carpels,--in all 6 dimerous whorls. But the formation of the corolla by the splitting of 2 petals does not agree with the development of the flower or bear comparison, and hence the only fact in favour of this theory is the otherwise prevailing correspondence with the Fumariaceæ. Yet it may be observed that in special cases each pair of long stamens clearly enough arises from one protuberance and even later on may be considerably united or entirely undivided (e.g. Vella); in other instances they are quite distinct from the beginning, and it is possible that this latter condition has become constant in the corolla. Lepidium ruderale and others have no corolla. Senebiera didyma has only 2 median stamens. Megacarpæa has several stamens, no doubt by dédoublement, as in Capparidaceæ.--The number of carpels may also be abnormally increased; Tetrapoma barbareifolium has normally 4 carpels with an equal number of placentæ and repla. It is supposed to be a variety of Nasturtium palustre.--The 2–4–8–10 greenish glands, which are found at the base of the stamens, are nectaries, morphologically emergences, and not rudimentary stamens. The forms of fruits are of great systematic significance, see the genera. In some species dimorphic fruits are present, e.g. Cardamine chenopodiifolia which has both ordinary Cardamine-siliquas and 1-seeded siliculas.

The curved embryo appears in five forms, which have systematic importance: 1. To the PLEURORHIZÆ belong those genera whose radicle (with the hypocotyl) lies bent upwards along the edge of the flat cotyledons (Fig. 399); to this group belong Cardamine, Nasturtium, Cheiranthus, Matthiola, Cochlearia, Draba, Iberis, Thlaspi, etc.; diagrammatic transverse section: ◯=.--2. To NOTORHIZÆ belong those whose radicle lies in an upward direction along the back of one of the flat cotyledons (Figs. 400, 413); e.g. Hesperis, Sisymbrium, Lepidium, Capsella, Camelina: ◯‖.--3. ORTHOPLOCEÆ differ from the Notorhizeæ in having the cotyledons folded (not flat) (Fig. 398 E, F); to this belong Brassica, Sinapis, Raphanus, Crambe, etc.: ◯>>.--4. SPIROLOBEÆ: the radicle lies as in the Notorhizæ, but the cotyledons are so rolled together that a transverse section of the seed cuts them twice; Bunias: ◯‖‖.--5. DIPLECOLOBEÆ: the cotyledons are folded forward and backward so that a transverse section cuts them several times; Subularia, Senebiera: ◯‖‖‖.

On germination the cotyledons appear above the ground as green leaves; in the Orthoploceæ they are bilobed, in the Lepidium-species divided.

1. =Silicula, broad replum= (Siliculosæ latiseptæ), valves flat or slightly vaulted, and the replum extends through the greatest width of the silicula (Fig. 404). The seeds are situated in two rows.

◯=: Cochlearia (Horse-radish): the siliqua is nearly spheroid; glabrous herbs, generally with fleshy, stalked leaves, and white flowers.--Draba has an oblong, lanceolate, somewhat compressed silicula; herbs with small rosettes of leaves, most frequently with stellate and long-stalked racemes.--Alyssum and Berteroa are whitish, on account of the stellate hairs; they have a more compressed and round or elliptical silicula. Vesicaria; Aubrietia. Lunaria (Honesty, Fig. 401): very broad and flat silicula with long stalk (the receptacle as in Capparidaceæ).

◯‖: Camelina (Gold-of-pleasure) has a spheroid, pear-shaped siliqua with a small rim passing right round (Fig. 402). Subularia (Awlwort), an aquatic plant with perigynous flower (Fig. 403) and folded cotyledons.

2. =Silicula, narrow replum= (Siliculosæ angustiseptæ), i.e. the replum is much shorter than the arched, more or less boat-shaped valves (Figs. 405, 406, 407).

◯=: 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.

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.