FLOWERS. 47 



Viburnum opulus, and in the outer whorls or Capitula 

 (heads) of some of the order Compositse. 



The mode of Fertilization, by which the flower becomes 

 a fruit or seed-vessel, must now engage our attention. 



Whatever may be the construction of flowers, they are all 

 perfected in one way, namely, by one or more grains of 

 pollen finding their way to the stigma or top of the pistil. 

 This necessary operation is brought about in different ways. 

 Insects and birds sometimes carry the pollen-dust from one 

 plant to another. Some plants discharge their pollen in 

 the air, and the wind conveys a portion of the powder to 

 the stigmas of similar plants ready for fertilization. In one 

 way or another the pollen is thus carried from the anther of 

 one plant to the stigma of another plant of its own species, 

 and the process of fertilization commences. Pollen is 

 produced very plentifully ; only a small proportion, in 

 comparison with the amount wasted, accomplishing its 

 mission. It is also a curious fact that in plants which 

 have both stamens and pistil, the pollen of the stamen is 

 frequently produced at a time when the stigma is not ready 

 for its reception. In such cases the pollen cannot fertilize 

 flowers of the plant producing it, because before the pistil 

 is perfect the pollen is shed. As a general rule, no perfect 

 seed can be produced without the help of pollen ; though 

 one or two instances to the contrary have been pointed out, 

 as in the case of a Queensland plant belonging to the 

 spurge family (Coslebogyne Ilicifolia) or Queensland spurge 

 holly. A plant of this species, without stamens, having a 

 pistil only, it is said produced perfect seed (?) in the Royal 

 Gardens at Kew. ' There was no possibility of pollen reach- 

 ing the pistil to fertilize it ; for at that time no pollen- 



