i9i i.] Identification and Eradication of Weeds. 463 



the early stages, while they are smooth and have long stalks 

 which are broad, channelled above, and unequal in length. 



Before the first " rough leaf " appears, the cotyledons are 

 respectively about J in. long by J in. broad (4 mm. by 6 mm.), 

 and iin. long by J in. broad (5 mm. by 8 mm.). With the 

 appearance of the "rough leaf" the cotyledons enlarge con- 

 siderably, attaining |- in. (1 cm.) in diameter, while the stalks 

 lengthen until about -f in. (2 cm.) in length. The first leaves 

 (Fig. 1, c) are dark green in colour, hairy and harsh to the 

 touch, and somewhat spatulate or elongate-oval. [At this 

 point it is important to distinguish the charlock seedling from 

 that of the turnip, in which the first leaves are lighter green, 

 nearly smooth, and about equal in length and breadth.] 



The progress of the seedling is now rapid (Fig. 1, d), the 

 cotyledons attaining \ in. long by § in. broad (1*2 cm. by 

 1 "6 cm.). The leaves are irregular, elongate-oval to oval or 

 ovate, toothed, light-green, alternate, and hairy, while the 

 stem is also hairy. 



Charlock appears to vary considerably, according to its 

 environment, and while some seedlings may be almost or quite 

 smooth until the third stage is reached, or even until they 

 approach flowering, they are, in general, harsh to the touch 

 when the second stage is passed. 



Mature Plant. — It may be said that in general appearance 

 charlock (Fig. 1, e) resembles the closely related turnip. The 

 root is stout and fibrous, the stem is branched, 1 to 3 ft. high, 

 and rough with hairs ; the leaves are rough and variable in 

 shape, being ovate, oblong to lanceolate, or sometimes lyrate, 

 and the lower ones are frequently segmented or lobed at the 

 lower and broader end — the upper leaves are sessile, the lower 

 ones stalked; the yellow cruciform flowers (Fig. 1, e') are 

 large — J in. or over in diameter — and occur in loose ter- 

 minal racemes ; the pods are smooth or rather rough, angular, 

 and spreading, and 1 to 2 ins. in length, the terminal third 

 being a stout beak, which often contains one seed. Flowering 

 continues throughout the summer months. 



Prevention and Remedy. — For the most part preventive and 

 remedial measures in the case of charlock are intimately con- 

 nected, but it may be said that there are three chief means of 

 dealing with this weed : (1) The use of pure seeds for sowing; 



