23 



N. Ord. CRUCIFER^E. 

 Tribe Brassicea. 



Genus Brassica, Linn. 



23. Brassica (Sinapis) alba, HooLf. $T.,in Hook.f.,Fl. Brit. 

 Ind., i, p. 157 (1872). 



White Mustard. 



Syn. Sinapis alba, Linn., and most authors. Leucosinapis alba, Spach. 



Figures. Steph. & Ch., t. 42; Nees, t. 402; Hayne, viii, t. 39; Berg, 

 Gharact., t. 85, f. 606 ; Curt., Fl. Lend., fasc. 5 ; Syme, E. B., i, t. 84. 



Description. An erect annual, usually about 2 feet high, with 

 a few ascending branches, stiff, bright green, bristly, with reflexed 

 hairs throughout. Leaves all stalked, pinnatifid, the lowest ones 

 with the terminal lobe large, and the divisions reaching to the 

 midrib, uppermost ones less deeply cut, rough with hairs. 

 Flowers as in B. nigra, but twice as large, and pedicels consider- 

 ably longer ; petals much paler yellow ; pistil hairy below, a little 

 longer than the stamens. Siliquas 1 1 J inches long, on divaricate 

 stalks, spreading, the lower half beaded with the 4 6 contained 

 seeds, the upper half occupied by a flat, vertical, nearly smooth 

 beak, curved upwards, which often has a seed contained in its 

 base, valves short, with 3 prominent veins, strongly bristly. 

 Seeds sub globular, about ^ inch in diameter, pale yellow ; testa 

 smooth to the naked eye ; embryo as in B. nigra, green. 



Habitat. White mustard is readily distinguished from black by 

 its smaller size, much larger flowers and seeds, and spreading 

 hispid pods with a long falcate beak. Like the latter plant it is 

 a frequent weed in England, but is more restricted to cultivated 

 ground, being especially a cornfield plant in calcareous districts ; 

 and has perhaps still less claim to be considered a British plant. 

 It occurs throughout Europe, especially in the south, where it is 

 probably native, and in Asia Minor, Algeria, aud China, and is 

 cultivated in England (Essex and Cambridgeshire) and in the 



