OEDEE XIII. — CRCCIFEEJE. 227 



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

 lanceoliite, entire, glabrout*. Sepals colored. Petals obovate, unguic- 

 ulate. Silique appresseil, about three quarters of an inch lung, gla- 

 brous. — Yellow. ©. June. Introduced. Black Muxtard. 



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

 to denmnd a notice of tlieir properties liere. There are circumstances connected with 

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

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

 possessiniT none of the active properties of mustard, these remainin": in the seed. But 

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

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

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

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

 Sidpko-i^inapisin, possessing the same properties as this oil, and formed b}' the aclian 

 of water. 



Gen-US XL— RAPH'ANUS. L. U— 2. 



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



seed.) 



Cali/x closed. Silique transversely many-celled. Seeds in 

 one row. Flowers in racemes, opposite the leaves. 



R. s.^Ti'vus, (L.) Pods terete, pointed. Hoots more or less fleshy, of 

 various forms. — 0. Asia. JladisK 



Genus XIL— DRA'BA. L. 14— L 

 (From the Greek drahe, acrid.) 



Silicle oblong-lanceolate or oval, minutely hispid, especially 

 along the margin, or glabrous. Seeds numerous. Ca/y.r 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-obloiig. Floweis large ; 

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

 4 — 8 inches. 



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

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

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

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

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



3. D. braciiycar'pa, (Nutt.) Stem simple or branched, leafy. Leaves, 

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

 cal ones roundish-ovate, i)etioled. 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 pubesc^jnt. — White. 0. 

 March — ^April. Middle Georgia. 



Genus XIIL— COROXOTUS. L. 14— L (Senebicra.) 

 (From the Greek korone, a crow, and poiis^ a foot) 



Silicle reniform, didymous, compressed contrary to the sep 



