Plants as Affected by Insufficient Light. 147 



them a strong flavor. The leaves surrounding the 

 head may be tied about it or broken over so as to shade 

 it from direct sunlight. Burst cabbage heads should 

 be cut at once to avoid the formation of chlorophyll 

 within them. 



B PLANTS AS AFFECTED BY INSUFFICIENT LIGHT. 



237. Insufficient Light is a Frequent Cause of 

 Abnormal Development in plants. Some of its effects 

 are 



a Excessive elongation of the cells of the internodes 

 (75), causing the plants to "draw up" or grow spin- 

 dling. 



b Deficient formation of chlorophyll (59), giving 

 the foliage a pale-green, yellowish or whitish tint, and 

 resulting in 



c Lessened food formation, causing reduced leaf de- 

 velopment and deficient vascular bundles (67). 



d Reduced transpiration tending to watery, weak- 

 celled growth. 



e Weakening of the color and flavor of some fruits, 

 as 'the apple and strawberry. 



f Preventing pollination (150). 



g 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.* Such plants, 

 though of species that normally grow upright, are 

 often unable to stand erect without support. Familiar 



* Tomato plants grown in winter on poorly-lighted benches are 

 often unfruitful even when they grow well and bloom freely. 



