620. A flower of Sinapis nigra

620. A flower of Sinapis nigra. 1. The stamens (4 long and 2 short) and pistil. 2. Plan of the flower, - stamens in 2 rows, outer row half wanting. 3. A silique, - 4. partly open, showing the septum with seeds attached. 6. Cross section of a seed, cetyledons conduplicate (0>>). 6. Cross section of a seed of Capsella, the cotyledons incumbent (0 || ). 7. Section of a winged seed of Arabis Canadensis, cotyledons accumbent (0=).

Herbs with a pungent, watery juice, and alternate, exstipulate leaves, with flowers cruciform, tetradynamous, generally in racemes, and bractless

Herbs with a pungent, watery juice, and alternate, exstipulate leaves, with flowers cruciform, tetradynamous, generally in racemes, and bractless. Sepals 4, deciduous; petals 4, hypogynous, with long claws and spreading limbs. Stamens 6, the 2 outer, opposite ones shorter than the 4 interior. Ovary 2-carpeled, 2-celled by a false partition, with parietal placentae. Fruit a silique, or silicle, usually 2-celled. Stigmas 2, sessile. Seeds 2-rowed in each cell, but often so intercalated as to form but one row. Embryo with the 2 cotyledons variously folded on the radicle. Albumen 0.

Illnst. 256, 312, 365, 447, 44S.

Genera 195, species 1600. This is a very natural order, larger than any of the preceding. The greater part of the species are found in the temperate zones. About 100 are peculiar to this continent.

Properties. The Crucifers as a class are of much importance to man. They furnish several Plimentary articles, which are very nutritious, as the Turnip Cabbage, Cauliflower; several others are used as condiments, as Mustard. Radish, Cochlearia, etc. They all possess a peculiar acrid, volatile principle, dispersed through every part, often accompanied by an ethereal oil abounding in sulphur. They are also remarkable for containing more nitrogen than other vegetables, for which reason ammonia is generally evolved in their putrefaction. In medicine they are eminently stimulant and antiscorbutic. None are really poisonous, although very acrid. The root of Isatis tinctoria affords a blue coloring matter.

Obs. The geneua of this large order were arranged into sub-orders by De Candolle, according to their various modes of folding the cotyledon upon the radicle, which modes are as follows: 1. Cotyledons accumbent, the radicle turned round and applied to the edges of the cotyledons, represented thus 0=. 2. Cotyledons incumbent, the radicle applied against the back of one of the cotyledons, 0 ||. 3. Cotyledons conduplicate, radicle folded as in the last case, but the cotyledons bent so as partly to enfold it, 0>>, as in the mustard.

In the analysis of the Crucifers it is indispensable that the specimens be in fruit as well as flower, and that the student bring to bear all his patience and resolution in the study of the above and other forms of structure in the seed, however minute. In the following synopsis the student may use in analysis either the artificial arrangement of the Genera or the less obvious but more natural arrangement of the

TRIBES.

§ SILIQUOSAE, - fruit a silique opening by valves. (Tribes.)

Tribe 1. Ababideae. Seeds flattened, often bordered; cotyledons 0=

..General 10

Tribe 2. Sisymbreae. Seeds oblong, not bordered; cotyledons 0 ||

...Gen. 11-14

Tribe 3. Brassickae. Seeds globular, cotyledons 0>>. Flowers yellow

Gen. 15, 16

§§ SILICULOSAE, - fruit a silicle opening by valves when more than 2-seedcd. (Tribes.)

Tribe 4. Alyssineae. Dissepiment broad. Cotyledors 0 =.

...Gen. 17 - 21

Tribe 5.CAMELINEAE. Dissepiment broad. Cotyledons 0 II .

Gen. 22, 23

Tribe 6.THLASPEAE. Dissepiment narrow. Cotyledons 0=.

.......Gen. 24

Tribe 7. Lepidineae. Dissepiment narrow. Cotyledons 0 ||

...Gen. 25 - 27

Tribe 8. ISATIDEAE. Dissepiment 0. Silicle 1-seeded, indehiscent

.......Gen. 28

§§§ LOMENTACEAE, - fruit a jointed silique, partitioned across. (Tribes.)

Tribe 9. Cakalineae. Cotyledons 0=, seeds compressed

........Gen. 29

Tribe 10. Raphaneae. Cotyledons 0>., seeds globous.

........Gen. 30

ARTIFICIAL KEY TO THE GENERA.

$ Fruit a silique. Seeds in a double row

.Genera 1, 2

Seeds in a single row. Flowers cyanic (a).

Flowers xanthic (b)

a Flowers purple, single. Stigma capitate. Plant native,...................

...Genera 3

a Flowers purple (or white and double). Stigmas horned. Cultivated..............

... Gen. 4, 14

a Flowers white or roseate. Siliques flattened, - raised on a filiform stipe...................

.......Gen. 18

- sessile, having no stipe,......

Gen. 5, 6, 7

b Seeds globular, with cotyledons conduplicate (0>>).................................

Gen 15, 16

b Seeds oblong or lens-shaped. Siliques terete or flattened, veinless...................

..Gen. 8, 9

Siliques squarish, valves 1 - 3-veined,

Gen. 10, 11, 12

§§ Fruit a silicle. Silicle turgid or flattened, with a broad partition (c).

Silicle flattened con'rary to the narrow partition (d).

Silicle with no partition, 1-seeded. Flowers yellow......................

.......Gen. 28

c Ornamental exotics. variously colored. Gardens...................

....Gen. 17, 18

C Native plants with - flowers cyanic, white....................................

Gen. 19, 20, 23

-flowers yellow. Silicles? oblong..........................

........Gen. 1

Silicles ovoid or globular.................

....Gen. 21,23

d Seeds several in each cell. Silicle triangular.................................................

.......Gen. 25

d Seeds only 2, - one in each cell. The two outer petals larger,............................

.......Gen. 24

The petals all equal..............................

....Gen. 26, 27

§§§ Fruit a loment, jointed and partitioned across.....................................

..Gen. 29, 80

1. NASTURTIUM, R. Br. Water Cress. (Lat. nasus tortus; from the effect of these acrimonious plants upon the nose.) Sepals equal at base, spreading; siliques subterete, generally curved upwards, sometimes shortened so as to resemble a silicle; valves veinless; seeds small, lens-shaped, ∞, in a double row (0=). - Aquatic plants with pinnate or pinnatifid lvs.

* Petals white. Siliques rather long (10 - 12")

..... No. 1

* Petals yellow. Siliques shortened (4 - 8"), but longer than the pedicels (a).

* Petals yellow. Siliques or silicles (1 - 6") shorter than the pedicels (b).

a Leaves pinnate or pinnatifid. Diffusely branched.

Nos. 2, 3

a Leaves lyrate, or merely toothed. Steins erect

Nos. 4, 5

b Petals not longer than the calyx, obscure.

Nos. 6,7

b Petals longer than the calyx, bright yellow

Nos. 8, 9

1 N. officinale R. Br. English Water Cress. Lvs. pinnate, lfts. ovate, sub-cordate, repand; petals white, longer than the calyx.-Order XIII Crucifeeae Crucifers 232 Brooks and springy places, rare. (Yellow Springs, 0.) Sts. decumbent, thick, branching, 6 - 12' long. Lfts. 3 - 7, broad, mostly rounded at base, obscurely toothed, terminal one largest. Fls. corymbed. Siliques hardly 1' long. Occasionally cultivated for salad. May, Jn. § ‡.

2 N. tanacetifolium Hook. Tansey-leaved. Upper leaf segm. confluent, lower distinct, oblong or roundish, sinuate-toothed teeth obtuse; pods linear-oblong.-Order XIII Crucifeeae Crucifers 233 Damp soils, Ga. and Fla., W. and N. W. to the Miss. Sts. smooth, diffusely branched from the base, 4 - 12' high. Root lvs. 2 - 4 long, narrow, regularly pinnate with 19 - 15 segm. in the larger plants, the 3 upper segm. often confluent. Fls. minute. Pods 4 - 8" long, slightly curved, on ped. 1/3 as long, and tipped with a distinct but short style. Mar., May.

β. obtusum. Lfts. mostly distinct, oval, obtuse; pods shorter (3 to 5"), twice longer than pedicel. (N. obtusum, Nutt.)

3 N. Walteri. Segm. of the lvs. all distinct, narrow, with a few linear, acute lobes or teeth; pods linear, -Order XIII Crucifeeae Crucifers 234 ? Ga. (Feay and Pond.) and Car. Rt. thick, blackish, with many strong fibres. Lvs. numerous, mostly radical or subcauline, 1 - 2 long, finely dissected, the terminal segm. 3-lobed. Sts. branched from the base (only?), 3 - 5' high, puberulent Fls. minute. Pods slender, about 5" long, ped. half as long; style distinct Mar., Apr. (Sisymbrium Walteri Ell.)

4 N. limosum Nutt. Lvs. lanceolate, toothed, lower ones pinnatified at base (lyrate), upper entire at base; pods elliptic-oblong (3 - 4"). -Order XIII Crucifeeae Crucifers 235 Edges of the Miss., La. (Hale.) Glabrous. Sts. erect, simple, branched only at top, 10 - 15' high. Lvs. all cauline and petiolate, the lower irregularly divided at base, where they touch the water. Rac. several. Fls. minute. Pods on very short pedicels, with styles much shorter. Apr., May. Hardly distinct from the next.