ORDER XIII. CRUCIFER^]. 227 



1. S. ni'gea, (L.) Lower leaves large, lyrate, scabrous; upper ones 

 lanceolate, entire, glabrous. Sepals colored. Petals obovate, unguic- 

 ulate. Silique appressed, about three quarters of an inch long, gla- 

 brous. — Yellow. 0. June. Introduced. Black Mustard. 



The seeds of the S. nigra (common mustard) are too extensively known and used 

 to demand a notice of their properties here. There are circumstances connected with 

 the exhibition of their well-known properties, which are singular and interesting. 

 The mustard -seeds, in a perfectly dry state, may be pressed and made to yield an oil, 

 possessing none of the active properties of mustard, these remaining in the seed. But 

 if the oil be obtained by water, it is powerful in its operation, producing speedy ves- 

 6ication. This latter oil it seems does not exist ready formed in the seed, but is formed 

 by the action of the water. The chemical difference of the two is, probably, that the 

 latter contains sulphur, as this is found, in the white mustard in a principle called 

 Sidpho-sinapisiri, possessing the same properties as this oil, and formed by the action 

 of water. 



Genus XI.— RAPH'ANUS. L. 14—2. 



(From the Greek raplianis, to appear quickly ; from the rapid germination of the 



seed.) 



Calyx closed. Silique transversely many-celled. Seeds in 

 one row. Flowers in racemes, opposite the leaves. 



R. sati'vus, (L.) Pods terete, pointed. Roots more or less fleshy, of 

 various forms. — 0. Asia. Radish. 



Genus XII.— DRA'BA. L. 14—1. 

 (From the Greek drdbe, acrid.) 



Silicle oblong-lanceolate or oval, minutely hispid, especially 

 along the margin, or glabrous. Seeds numerous. Calyx equal. 

 Petals emarginate or entire. 



1. D. cuneifo'lia, (Nutt.) Stem, leafy at the lower part, very pu- 

 bescent, slender. Leaves with few teeth ; cauline ones oblong-ovate, 

 narrowed at the base ; radical ones spatulate-oblong. Flowers large ; 

 petals several times the length of the calyx. — White. 0. Florida. 

 4 — 8 inches. 



2. D. Carolinia'na, (Walt.) Stem leafy and hispid at the base, na- 

 ked and smooth above. Leaves hispid, entire. Flowers corymbic or 

 racemed ; petals oblong, twice as long as the sepals, or minute, and 

 sometimes wanting. Silicle nearly linear, glabrous, 4 — 6 lines long, 

 many-seeded. — White. 0. April and June. Mid. Geo. 1 — 6 inches. 



3. D. brachycar'pa, (Nutt.) Stent simple or branched, leafy. Leaves, 

 jauline ones linear or oblong, with 2 or 3 minute teeth or entire ; radi- 

 cal ones roundish-ovate, petioled. Flowers in racemes, many-flowered ; 

 silicles oval, glabrous, cells 5 — 6 seeded ; petals entire or slightly emar- 

 ginate. 



Var. fastigia'ta, (Nutt.) Stein more pubescent, seldom branched; 

 radical leaves generally 4-toothed, silicle pubescent. — White. 0. 

 March — April. Middle Georgia. 



Genus XIII.— CORONO'PUS. L. 14—1. {Senebiera.) 

 (From the Greek Jcorone, a crow, and pons, a foot.) 



Silicle reniform, didymous, compressed contrary to the sep- 



