CRUCIFERAE , or Crucifer
See also:family, a natural
See also:order of flowering
See also:plants, which derives its name from the cruciform arrangement of the four petals of the flower . It is an order of herbaceous plants, many of which, such as wallflower, stock,
See also:radish and others, are well-known
See also:garden or
See also:field-plants . Many of the plants are annuals; among these are some of the commonest weeds of cultivation, shepherd's
See also:purse (Capsella Bursa-pastoris), charlock (Brassica Sinapis), and such
See also:Diagram (Brassica) . Flower with Perianth removed . (After Baillon.) plants as hedge mustard (Sisymbrium officinale),
See also:Jack-by-thehedge (S . Alliaria or Alliaria officinalis) . Others are biennials producing a number of leaves on a very
See also:stem in the first
See also:year, and in the second sending up 'a flowering shoot at the expense of the nourishment stored in the thick tap-
See also:root during the previous
See also:season . Under cultivation this root becomes much enlarged, as in
See also:turnip, swede and others . Wallflower (Cheiranthus Cheiri) (fig . I) is a perennial . The leaves when
See also:borne on an elongated stem are arranged alternately and have no stipules . The
See also:flowers are arranged in racemes without bracts; during the
See also:life of the flower its stalk continues to grow so that the open flowers of an inflorescence stand on a level (that is, are corymbose) .
The flowers are
See also:regular, with four
See also:free sepals arranged in two pairs at right angles, four petals arranged
See also:cross-wise in one series, and two sets of stamens, an
See also:outer with two members and an inner with four, in two pairs placed in the
See also:line of the flower and at right angles to the outer series . The four inner stamens are longer than the two outer; and the stamens are hence collectively described .as tetradynamous . The
See also:pistil, which is above the
See also:rest of the members of the flower, consists of two carpels joined at their edges to
See also:form the ovary, which becomes two-celled by subsequent ingrowth of a septum from these
See also:united edges; a
See also:row of ovules springs from each edge . The fruit is a pod or siliqua splitting by two valves from FIG . 4.—Cruciferous Fruits . (After Baillon.) A, Cheiranthus Cheiri . D, Lunaria biennis, showing the septum B, Lepidium sativum . after the carpels have fallen away . C, Capsella Bursa-pastoris . E, Crambe maritima . below upwards and leaving the placentas with the seeds attached to the replum or framework of the septum . The seeds are filled with the large embryo, the two cotyledons of which are variously folded .
In germination the cotyledons come above ground and form the first
See also:green leaves of the plant .
See also:Pollination is effected by aid of
See also:insects . The petals are generally
See also:white or yellow, more rarely
See also:lilac or some other
See also:colour, and between the bases of the stamens are
See also:honey-glands . Some or all of the anthers become
See also:twisted so that insects in probing for honey will
See also:touch the anthers with one side of their
See also:head and the capitate stigma with the other . Owing, however, to the close proximity of stigma and anthers, very slight irregularity in the movements of the visiting
See also:insect will cause self-pollination, which may also occur by the drop- A ping of pollen from the FIG . 5.—Seeds of Cruciferae cut anthers of the larger stamens across to show the radicle and on to the stigma. cotyledons . (After Baillon.) Cruciferae is a large order A, Cheiranthus Cheiri. containing nearly 200 genera B, Sisymbrium Alliaria . and about 1200
See also:species . It Figures 2-5 are from Strasburger's Lehrbuch has a
See also:world-wide distribution, der Botanik, by permission of Gustav Fischer . but finds its chief development in the temperate and frigid zones, especially of the
See also:northern hemisphere, and as Alpine plants . In the subdivision of the order into tribes use is made of differences in the form of the fruit and the manner of folding of the embryo . When the fruit is several times longer than broad it is known as a siliqua, as in stock or wallflower; when about as long as broad, a silicula, as in shepherd's purse .
A C D The order is well represented' in Britain—among others by
See also:Nasturtium (N. officinale,
See also:cress), Arabis (
See also:rock-cress), Cardamine (bitter-cress), Sisymbrium (hedge mustard, &c.; S . Trio is
See also:rocket, so-called because it sprang up after the
See also:fire of 1666), Brassica (cabbage and mustard), Diplotaxis (rocket), Cochlearia (
See also:scurvy-grass), Capsella (shepherd's purse), Lepidium (cress), Thlaspi (
See also:penny-cress), Cakile (
See also:sea rocket), Raphanus (radish), and others . Of economic importance are species of Brassica, including mustard (B.
See also:nigra), white mustard, used when
See also:young in salads (B.
See also:alba), cabbage (q.v.) and its numerous forms derived from B. oleracea, turnip (B. campestris), and swede (B . Napus), Raphanus sativus (radish), Cochlearia Armor a c i a (
See also:horse-radish), Nasturtium officinale (water - cress),. showing Flower and Fruit . Reduced . Lepidium sativum (garden cress) . Isatis affords a blue dye,
See also:woad . Many of the genera are known as ornamental garden plants; such are Cheiranthus (wallflower), Matthiola (stock), Iberis (candy-tuft), Alyssum (
See also:Alison), Hesperis (
See also:violet), Lunaria (honesty) (fig . 6), Aubrietia and others .
CRUCIAL (from Lat. crux, a cross)
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