ORDER 13. CRUCIFER^E. 227 



by a false partition, with parietal placentae. Fruit a silique, or silicle, usually 2- 

 celled. Stigmas 2, sessile. Seeds 2-rowed in e,ach cell, but often so intercalated 

 as to form but one row. Embryo with the 2 cotyledons variously folded on the 

 radicle. Albumen 0. 



Illust 256, 812, 365, 447, 443. 



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. Aboat 100 are peculiar to 

 this continent. 



Properties. The Crucifers as a class are of much importance to man. They furnish several 

 alimentary articles, which are very nutritions, 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 etherial oil 

 abounding in sulphur. They are also remarkable for containing more nitrogen than other vege- 

 tables, 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. 



Ob. The genera 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 follow;-: 

 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, II . 8. Cotyledons conduplicate, radicle folded as in the last case, but the coty- 

 ledons 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 Lis patience and resolution in the study of the 

 above and other forma of structure in the seed, however minnte. In the following synopsis the 

 student may use in analysis either the artificial arrangement of the Genera or the less obvioua 

 but more natural arrangement of the 



TRIBES. 



SILIQUOS^E, fruit a silique opening by valves. (Tribes.) 



Tribe 1. AKABIDE.E. Seeds flattened, often bordered ; cotyledons 0= Genera 1 10 



Tribe 2. SISIMBRE.C. Seeds oblong, not bordered ; cotyledons II Gen. 11 14 



Tribe 3. BEASSICE-E. Seeds globular, cotyledons 0. Flowers yellow Gen. 15, 16 



SILICULOS^E, fruit a silicle opening by valves when more than 2-seeded. (Tribes.) 



Tribe 4. AIYSSINE^E. Dissepiment broad. Cotyledors 0= Gen. 17 21 



Tribe 5. CAXEIJNBA Dissepiment broad. Cotyledons Oil Gen. 22, 23 



Tribe 6. THLASPE.E. Dissepiment narrow. Cotyledons 0= Gen. 24 



Tribe 7. LEPIDINILE. Dissepiment narrow. Cotyledons || Gen. 2527 



Tribe 8. ISATIDE.E. Dissepiment 0. Silicle 1-seeded, indehiscent Gen. 28 



LOMENTACE^E, fruit a jointed silique. partitioned across. (Tribes.) 



Tribe 9. CAKALINEJB. Cotyledons 0=, seeds compressed Gen. 29 



Tribe 10. KAPHANE^E. Cotyledons 0, seeds globous. Gen. 30 



ARTIFICIAL KEY TO THE GENERA. 



Fruit a silique. Flowers cyanic (a). Flowers xanthic (c)- 



a Seeds in a double row Genera 1, 2 



a Seeds in a single row (b). 



b Siliques terete (petals showy, purple) Genera 3, 4, 14 



b Siliques flattened, no stypo. Petals white Gen. 5 7 



b Siliques flattened, on a filiform stype. Pet. white Gen. IS 



C Seeds globular (0>>) / Gen. 15. 16 



C Seeds oblong or lens-shaped (d). 



d Siliques terete or flattened, veinless Gen. 8. 9 



d Silique squarish, valves each 1 3-veined Gen. 10 12 



Fruit a silicle 2-celled (a) or 1-celled and 1-seeded in Isatis (c). 

 a Siiicle turgid or flattened with a broad partition (b). 

 a Silicle flattened contrary to the narrow partition (c). 



b Native. Flowers cyanic Gen. 17, IS, 2o 



b Native. Flowers xanthic Gen. 1, 19, 22 



b Exotic garden flowers, variously colored Gen. 20. 21 



C Seeds many Gen. 24, 25 



C Seeds 2 only. "Wild and cultivated Gen. 26,27 



C Seedl only. Cultivated ...Gen. 2S 



Fruit a loment, jointed and partitioned crosswise ... Gen. 29. 80 



