COMPOSITAE (COMPOSITE FAMILY) 



543 



In rich, moist soil this weed sometimes 

 attains a height of ten feet, but is more 

 often three to six feet tall,. Stem slender, 

 smooth, often glaucous, sometimes of a 

 purplish tinge but most commonly deep 

 green. Lower and basal leaves lance- 

 shaped in outline but deeply and irregu- 

 larly lobed, the terminal segment large 

 and acutely pointed, the lateral ones un- 

 equal in number and size, not opposite, 

 and frequently with points turned back- 

 ward, narrowing to margined petioles ; 

 upper leaves much smaller, often entire 

 and sessile". Heads numerous, in a loosely 

 branching terminal panicle and in short 

 axillary clusters ; heads yellow, hardly 

 more than a quarter-inch broad, the in- 

 volucre cylindric, its inner row of bracts 

 linear, the outer ones short and spreading. 

 Achenes oblong-oval, tipped with a slen- 

 der beak; pappus white, very fine and 

 silky. The plant has a strong, unpleasant 

 odor resembling opium, and, though cattle 

 and sheep eat it readily, it will damage 

 dairy products if milch cows get much of 

 it. (Fig. 376.) 



Means of control the same as for 

 Prickly Lettuce. 



FIG. 376. Wild Let- 

 tuce (Lactuca canadensis). 

 XJ. 



ARROW-LEAVED WILD LETTUCE 



Lactuca sagittifblia, Ellis 



Other English names: Devil's Ironweed, Horseweed. 



Native. Biennial. Propagates by seeds. 



Time of bloom : July to September. 



Seed-time: August to November. 



Range: New Brunswick and Ontario to Georgia, westward to the 



Rocky Mountains. 

 Habitat : Dry, open soil ; fields, meadows, waste places. 



