PRICKLY LETTUCE 



the way the leaves place themselves when the heat 

 becomes too great. 



"The long, oblong leaf has a thick, fleshy midrib, 

 and at the base are developed two pointed lobes 

 which clasp the stalk. The leaf is soft and leathery 

 and always seems succulent, because it retains its 

 moisture; it has a ruffled edge near its base, which 

 gives it room for turning without tearing its margin. 

 Each leaf tips over sidewise toward the stem, and as 

 far as necessary to bring one edge uppermost. Thus 

 the sun cannot reach its upper surface to pump water 

 from its tissues. The ruffled margin of the upper 

 edge is pulled out straight when the leaf stands in this 

 position, while the lower margin is more ruffled than 

 ever. Thus it stands triumphantly, turning edgewise 

 to the sun, retaining its moisture and thriving when 

 cultivated plants are dry and dying." 



The plant is an especial pest in the wheat-fields 

 of the West, in that the hard stems dull the reaping 

 knives, and the milky juice makes the weed very 

 troublesome in thrashing-machines when the crop is 

 thrashed immediately after reaping, without drying in 

 the shock, as is so frequently done in the West. 



In order to grasp the necessity of cutting down such 

 noxious weeds one has only to cut a well-grown speci- 

 men in flower and count the heads, in bud, in bloom, 

 and in seed. Such a plant, under rather than over 

 size, bore three hundred and twelve heads, and averag- 

 ing fifteen florets for each head aU of which were fer- 

 tfle, gives a total of over forty-five hundred seeds, each 

 one equipped with a plumy parachute to carry it 

 whither the wind pleased. 



The Willow Lettuce, Lactuca saligna, very similar to 

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