CAPPAEIDACE^. 437 



flowers, such as Wallflower, Stock, Eocket, and Honesty, are found 

 in this order. Brassica oleracea is the original species whence all the 

 varieties of Cabbage, Cauliflower, Broeoli, and Savoys, have been 

 obtained by the art of the gardener. The part of the Cauliflower used 

 as food is the deformed flower-stalks. Brassica Rapa is the common 

 Turnip, while jBroasica campestris is the source of the Swedish turnip. 

 Brassica Napus, Eape or Coleseed, yields Colza and Carcel oUs. Some 

 consider Brassica campestris, Eapa, and Napus, as sub-species. Bras- 

 sica chinensis yields Shanghae oil. Lepidium sativum is the common 

 Cress, and Baphanus sativus the Eadish. Orambe maritima is the Sea- 

 kale. The seeds of Sinapis m,igra (Brassica nigra of some) furnish table 

 mustard. These contain a bland flxed oil, a peculiar bitter principle, 

 myronic acid, and another principle analogous to albumen or emulsin, 

 called myrosine. When water is added, the myronic acid and myro- 

 sine, by their combination, form a pungent volatile oil, containing 

 sulphur and nitrogen, which gives to mustard its peculiar properties ; 

 a crystallisable substance called myronate of potassium, now called 

 sinigrin, is found in Mustard. Sinapis alba furnishes white Mustard, 

 which contains more fixed oil than black mustard. It does not, however, 

 contain myronic acid, but an analogous principle called sinapin, or 

 sinapisin, which, by combination with another principle, forms an 

 acrid compound, but not a volatile oil. The mustard of Scripture, 

 according to Eoyle, is not a species of Sinapis, but Salvadora persica, 

 belonging to the natural ordej Chenopodiacece. This view is not con- 

 firmed by Dr. Tristram, who says that the mustard plant of Scripture 

 (sham) is Sinapis nigra, Black Mustard, while Salvadora is a tropical 

 plant, growing on the north of the Dead Sea, and not found generally 

 in Palestine. Many other Cruciferous plants yield volatile oUs con- 

 taining sulphur, and the seeds of many yield by expression a bland 

 fixed oil, such as Eape-seed oil. GochUaria officinalis, common Scurvy- 

 grass, is used as a stimulant. Oocklearia Armoracia, or Armoracia rusti- 

 cana, the Horse-Eadish, has irritant and even vesicant qualities. Ana- 

 statica hierochiirCtina, Eose of Jericho, is remarkable for the hygrometric 

 property of the old withered annual stems, which are rolled up like a 

 ball in dry weather, and drifted about by the winds in the deserts of 

 Syria and Egypt. If rain falls, they resume their original position. 

 They thus continue for many years to curl up and expand, according 

 to the state of the atmosphere. The genus Schizopetalon is remark- 

 able on account of its tetracotyledonous (having four cotyledons) 

 embryo. Isatis tinctoria, Woad, when treated like Indigo, yields a 

 blue dye. Isatis indigotica is the Tein-Ohing, or Chinese Indigo. . 

 Pringlea antiscorbutica, Kerguelen Island Cabbage, is found in that 

 island, as well as in Tristan d'Acunha, Marion Island, and Heard 

 Island. It has no petals, no glands, and the stigma is hairy. 



Order 12. — OAPPAEiDACEiE, the Caper Family. (Polypet. Hypog.) 



