CH. VI, 13] ECONOMICS OF FLOWERS 343 



control mechanism becomes inoperative while the growth 

 energy is still forcing forward the growth of the part, then 

 the part seems to be controlled by whatever structural con- 

 dition happens to be strongest at the moment. 





 13. ECONOMICS, AND TREATMENT IN ^CULTIVATION, OF 



FLOWERS 



Flowers, unlike the five other primary plant parts, have 

 few economic uses, aside from the beauty they give to our 

 gardens. That, however, is surely a utility of civilization, 

 and besides it maintains great business interests in seed 

 firms and nurseries which supply ornamental flowers, trees, and 

 shrubs. In a few cases perfumes are extracted from flowers, 

 which also supply the nectar elaborated by bees into honey. 

 But otherwise their direct uses are insignificant. 



Turning to the cultivation of flowers, we find some features 

 of gardening practice dependent on their physiology. 



Since showy flowers are cross-pollinated by insects, those 

 who grow seeds or fruits for market find it well to keep 

 Bees, best of cross-pollinators, in their gardens, or even 

 their greenhouses, where crops of Tomatoes or Cucumbers 

 are forced for early market. It is true the pollination can 

 be effected artificially by use of fine brushes, as often done 

 for special purposes; but Bees are more economical. In 

 another way this relation of insects to flowers affects practical 

 interests, for if the blossoming time of our fruit trees, Apples, 

 Pears, and others, falls cold and wet, the insects are not active 

 and pollination is only partial, which is one cause of poor 

 fruit years. 



The reciprocal balance, already described (page 207), 

 between vegetation and reproduction, makes it possible for 

 gardeners to promote flowering by checking the stem and 

 leaf growth, either through withholding fertilizers, by root 

 pruning, or by other devices known in the business. Pruning, 

 in orchards, has chiefly this use, as earlier noted (page 207). 

 These methods, however, have strict limitations, and are 



