Plants as Affected hy 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 bt Insufficient Light. 



237. Insufficient Light is a Frequent Cause of Ab- 

 normal Development in plants. Some of its effects 

 are 



a— Excessive elongation of the cells of the intemodes 

 (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 re- 

 sulting 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 :^ruits, 

 as the apple and strawberry. 



f — Preventing pollination (150). 



g — Reducing fruitfulness. 



Owing to these causes, plants grown in deficient light 

 have tail, 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. Plamiliar exam- 



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

 often unfruitful even when they grow well and bloom freely. 



