PLANTS INFLUENCED BY THEIR SURROUNDINGS 119 



\ Very interesting results are "obtained by growing 

 plants in darkness. \To do this out-of-doors it is only 

 necessary to cover ftie plant with a section of stove- 

 pipe, a wooden box, or a barrel. Within doors the plant 

 may be placed in a dark closet or box. Such plants 

 (figures 66 and 67) 

 have very long, 

 slender stems (the 

 nodes are far 

 apart) ; they are 

 pale in color, have 

 little woody fiber, 

 and are very weak. 

 This fact is taken 

 advantage of in 

 bleaching aspara- 

 gus, celery, and 

 rhubarb for market. 

 The celery is either 

 "hilled" up or 

 covered with gunny 

 sacks, or the light is 

 kept out by means 

 of boards; the leafstalks are thus bleached and made 

 tender and succulent. The "laying," or^ lodging of _ 

 wheat, is due to excessiv<Tshadmg~of the lower portion 

 of the stalk, which results in too little production of 

 woody fiber. 



FIG. 67. The potato plant at the left grew 

 in a moist, dark place ; the one at the right 

 in a very dry and sunny spot. 



