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) 

 independent of heat 

 and thus tends to ex- 

 haust the plant of water. 



Fig. 61. — Lath screen used for shading 

 coldframes and tender plants in the 

 open ground. 



Various devices are used to 



break the force of the solar rays. 



137 



In out-door culture, 



