CRUCIFEROUS TRIBE. 



63 



erect branches, from 1 to 2 feet high, and small yellow 

 flowers. It grows iri waste places, and by roadsides, 

 where it seems to have a peculiar aptitude for collecting 

 and retaining dust. Fl. June, July. Annual. 



SISYMBRIUM OFFICINAL^ (Common Hedge Mustard). 



2. S. Irio (London Rocket). Leaves deeply lobed, 

 with the points turned backward, toothed, smooth as 

 well as the stem ; pods erect. A leafy herb about 2 

 feet high, with small yellow flowers, growing in waste 

 ground chiefly about London, where it covered the 

 ground in the spring after the great fire. Fl. July, 

 August. Annual. 



3. S. Sophia (Flixweed). Leaves twice pinnatifid, 

 slightly hairy ; petals shorter than the calyx. More 

 slender than either of the preceding, with small greenish 

 yellow petals, which are almost hid by the calyx, and 

 numerous erect pods, which when ripe have the appear- 

 ance of being beaded, from the numerous projecting seeds. 

 Not uncommon in waste places. It was called by the 



