THE SUNFLOWER FAMILY 175 



Injury: A coarse, weedy plant, often quite prevalent in 

 clover fields and the margins of winter wheat. Like other species 

 of wild lettuce it possesses a narcotic poison, commonly known 

 as lettuce-opium, and is said to be unwholesome to live stock. The 

 plants frequently occur in dense masses, and when young and 

 tender are readily eaten by horses, cattle and sheep. Prickly 

 Lettuce harbours fungus diseases common to cultivated lettuce 

 and some other crops. 



Remedy: The seed is short-lived and if the plant is kept 

 closely cut and prevented from seeding in waste places for two 

 or three years it will soon disappear from cultivated areas. 

 Clean waste lands and seed to permanent vigorous grasses. 

 Ordinary methods of cultivation will suppress it in fields. 



ALLIED SPECIES: Wild Lettuce or Horse Weed (Lactuca 

 canadensis L.). A tall annual or biennial weed, hairless, smooth, 

 upper leaves lance-shaped, without any teeth or divisions, lower 

 leaves roundly pinnatifid. Flowers yellow, in open panicles. 



The seed (Plate 76, fig. 98) is about 1/6 of an inch long, broadly 

 ovate, ending in a thin beak, crowned with a silky pappus. 

 Middle rib very prominent. The surface is rough, dark brown, 

 the centre of the seed darker than the wing-like and somewhat 

 radiate margin. 



Wherever there are an Abundance of these Thistles, and such other of the rooted 

 Kinds, let the Farmer understand that the Ground will cost him much more Expence 

 than under any other Condition, whatever Method he follows. 



Thomas Hale, The Compleat Body of Husbandry, 1756. 



The putting forth of certain Herbs, discovereth of what nature the Ground where 

 they put forth is; as wild Thyme sheweth good Feeding Ground for Cattel; Bettony and 

 Strawberries shew grounds fit for Wood; Camomile sheweth mellow Grounds fit for Wheat', 

 Mustard-Seed growing after the Plough, sheweth a good strong Ground also for Wheat 

 Burnet sheweth good Meadow, and thp like. 



Bacon, Natural History, 1625. 



