The Flower. 93 



only in special cases, as with seedling trees. It is gener- 

 ally a reproach to the care or knowledge of the cultiva- 

 tor, if his trees of bearing age cannot form flower-buds 

 without such choking. 



Fruit trees grafted on slightly uncongenial stocks some- 

 times flower and fruit more freely for a time than when 

 growing on their own roots, because the imperfect union 

 of cion and stock (.383) forms an obstruction to the root- 

 ward food-current. 



Section X. The Flower 



139. The Flower is the developed and expanded flower- 

 bud (132). Its office is to i^rovide for the formation of 

 new plants of its kind (rei^roduction, 16). Some plants, 

 as the quack grass,* Canada thistle f and horseradish J 

 multiply freely in nature without the aid of flowers, and 

 nearly all plants may be multiplied in culture by other 

 means, but in most of the higher plants, the flower is the 

 natural organ of reproduction, and the only organ devoted 

 solely to this end. 



140. Flowers Tend to Exhaust the Plant, since they are 

 formed from the food prepared by the leaves. But since 

 flower-buds are not usually formed until the needs of 

 growth are provided for (135A), the normal production 

 of flowers does not injure the plant. In certain cases, 

 however, as in plants weakened by recent transplanting 

 or in cuttings (358), flower-buds should be removed as 

 soon as discovered, to prevent their exhaustive influence. 



141. The Parts of the Flower. The complete flower is 

 composed of four different parts or organs. A knowledge 



* Agropyrum repeivs. f Cnicus oi'vensis. % ^ctsturtiuTn Armoracia, 



