UNFAVORABLE LIGHT AND WIND 139 



236. Cauliflower heads should be sheltered from sun- 

 light to prevent the formation of chlorophyll in their 

 cells (59), which darkens their color and gives them a 

 strong flavor. The leaves surrounding the head may 

 be tied about it or broken over so as to shade it from di- 



FIG. 64. Board shade for recently-set plants, or for cuttings not yet 



rooted. 



rect sunlight. Burst cabbage heads should be cut at 

 once to avoid the formation of chlorophyll within them. 



PLANTS AS AFFECTED BY INSUFFICIENT LIGHT 



237. Abnormal development. Insufficient light is a 

 frequent cause of abnormal development in plants. 

 Some of its effects are : Excessive elongation of the cells 

 of the internodes (75), causing the plants to " draw up " 

 or grow spindling; deficient formation of chlorophyll 

 (59), giving the foliage a pale-green, yellowish or whitish 

 tint, and resulting in lessened food formation, causing 

 reduced leaf development and deficient vascular bundles 

 (67) ; reduced transpiration tending to watery, weak- 

 celled growth ; weakening of the color and flavor of some 

 fruits, as the apple and strawberry; preventing polli- 

 nation (150) ; reducing fruitfulness. 



Owing to these causes, plants grown in deficient light 

 have tall, slender, weak stems; few, small, pale leaves 

 and scanty roots and are often unfruitful. Tomato 



