CHAP. V. FUNCTION OF REPRODUCTION. 251 



FIRST PERIOD OF REPRODUCTION. 



(246.) Flowering. When the flower-bud is dis- 

 tinguishable, the parts of which the .flower is com- 

 posed are in a very rudimentary state. The perianth 

 especially, continues for some time very small in pro- 

 portion to the anthers, which are more early deve- 

 loped. A gradual enlargement of all the parts of the 

 flower continues to take place till the period of ex- 

 pansion arrives. This expansion may be likened to 

 the age of puberty in animals ; and when completed, 

 terminates the first period of the function of reproduc- 

 tion. In herbaceous plants, it is very frequently effected 

 the same year in which they have germinated from the 

 seed ; but there are some which do not flower until the 

 second year, and others not until later. Some under- 

 shrubs also begin to flower within the year ; others 

 not until after a second, third, or fourth has elapsed. 

 Shrubs and trees, with very few exceptions, never 

 flower before the second or third year at least, and 

 very many of them attain a considerable age before 

 they show any symptom of flowering. It may be as- 

 serted of trees, almost as a general rule, that the period 

 when they commence flowering is protracted in pro- 

 portion to the slowness of their growth. 



(24-7.) Stimulants to Inflorescence. Although we 

 cannot comprehend the primary causes upon which 

 the formation of the flower-bud depends, we can con- 

 nect several phenomena which attend its development 

 with the operation of specific influences. For instance, 

 an increase of temperature accelerates, and a dimi- 

 nution retards the period of flowering ; and accord- 

 ing to the nature of the individual, these causes also 

 operate in predisposing its buds to assume the cha- 

 racter of leaf-buds or flower-buds. Many plants, when 

 removed from a warm climate to a cold one, or vice 

 versa, will flourish without ever producing flowers ; and 

 others which are able to flower, never perfect their 



