CHAPTER X 



THE PLANT AS AFFECTED BY UNFAVORABLE 

 LIGHT AND WIND 



PLANTS cannot grow or subsist in darkness. The de- 

 gree of light affects them strongly. Winds increase 

 transpiration if they are dry; and they affect plants in 

 other ways. These subjects now need our attention. 



EXCESSIVE LIGHT 



235. Shading plants. The unobstructed rays of the 

 sun are often injurious to young seedlings, to unrooted cut- 

 tings and to plants re- 

 cently transplanted. It 

 is difficult to separate 

 the influences of light 

 and heat, since the 

 heat is usually greatest 

 where the sun's rays are 

 brightest ; but bright 

 light probably stimu- 

 lates transpiration (74) 



i j f i FIG. 61. Lath screen used for shading 



independent of heat coldframes and tender plants in the 



and thus tends to ex- open ground, 

 haust the plant of water. Various devices are used to 

 break the force of the solar rays. In out-door culture, 



137 



