DEVELOPMENT OF FLOWERS. 



LESSON V. 



Development and Functions of Flowers Flora's Calendar 

 Flora's Clock Fertilization of Flowers Fruit Epicarp 

 Mesocarp Endocarp Carpels Classification of fruits 

 Seeds ; their structure Embryo Coty'ledons Germination. 



OF THE DEVELOPMENT AND FUNCTIONS OF FLOWERS. 



1. Flowers are formed in certain plants long before 

 they appear externally ; in the palms, for example, they 

 remain concealed a year or even several years before they 

 show themselves. They first appear in the form of a 

 bud, which is generally a little larger than the buds of 

 the leaves, and for a certain time their different constituent 

 parts remain contracted ; they are then designated under 

 the name of flower-bud (fig. 114) ; finally, when they 

 approach a little nearer to the term of their growth, they 

 expand or blow, and it is to this phenomenon that we 

 ordinarily apply the name of inflorescence or flowering 

 of plants. 



2. Plants do not fade till they attain a certain age, which 

 varies according to the species and according to circumstances, 

 but this period is deferred in proportion to the slowness of the 

 growth of the plant and the time it is destined to live. For 

 instance, herbs fade on the first year of their existence ; some 

 do not fade until the second year ; most shrubs only die in the 

 second, third, or even fourth year; and in trees, this phenome- 

 non is more tardy. A certain degree of heat is necessary to 

 effect inflorescence, and it is remarked that the same plant begins 

 to fade sooner in warm countries than in cold ; it sometimes even 

 happens, in the latter, that certain plants, if they can live at all, 

 never fade. Too much moisture, and superabundant nourish- 

 ment, by favouring the development of the leaves and stem, often 

 contribute to retard inflorescence. 



3. When a perennial plant has begun to blossom, it ordinarily 

 produces new flowers every year at about the same period ; some- 

 times, however, this periodical return of inflorescence does not 



Explanation of Fig. 114. A flower bud, magnified. 



1. How do flowers first appear ? What is a flower-bud ? What is inflo- 

 rescence ? 



2. When do plants fade? What circumstances exert an influence over 

 the duration of inflorescence ? 



3. Is the recurrence of inflorescence regularly periodical in plants ? 



