41 
height, in which birds have their nesting places, and, by eating and 
excreting the seeds, help to spread this pernicious weed. 
Description.—The rather stiff, dark-green, branching stem of black 
mustard is from 4 to 6 feet in height. The lower part of the stems 
and branches is more or less bristly hairy, but the upper part is 
usually smooth. 
The leaves are dark green, somewhat rough, with bristly hairs, and 
are all borne on stalks. The lower leaves are lobed, the terminal lobe 
being the largest and the two 
or more lateral ones smaller. 
The leaves toward the top of 
the plant become lance shaped 
and are slightly toothed. 
The flowers of black mus- 
tard appear from June to Sep- 
tember, and are of a bright 
yellow color. They are rather 
small, scarcely a quarter of an 
inch in diameter, the four pet- 
als spreading and each consist- 
ing of a rounded blade with a 
narrowclaw. The petals alter- 
nate with the pale-green sepals 
or calyx lobes. The flowers 
appear in clusters at the ends 
of the elongating stems, fol- 
lowed from July to November 
by the numerous erect pods 
crowded against the stem in 
dense narrow clusters. The 
pods are about 1 inch inlength, 
quadrangular, smooth, and 
tipped at the apex by the short, 
persistent style. The soot 
contained in the pods are very 
numerous, small, about one twenty-fifth of an inch in diameter, ees : 
lar, blackish peti: and finely pitted. 
Fia, 30.—Black mustard (Brassica nigra (L.) Koch). 
The plant is an énmuaks and if care is taken to prevent the distrib os 
tion of the seeds it is not difficult to exterminate. The seeds possess 
great vitality, and may remain in the ground for a before 
germinating. = 
Collection of seeds——The tops may be pulled when most of the pads 
are nearly mature, but before they are ready to spring open. — ‘They a ss 
should then be _ on a clean, c= foe or abet, —— pode = : 
7 aS 
