FERTILIZATION OF THE FLOWERS. 



39 



There appears to be no fixed rule with regard to the fertiliza- 

 tion of the flowers of a genus. 



There are instances among plants in which the flowers of the 

 same species are fertilized in a different manner in different 

 Reasons and in different countries, and certain specimens of a 

 species are fertilized in an exceptional manner during the same 

 season or in the same neighborhood. 



As a rule, a certain specified flower of a grass remains open 

 only for a very short time, but different flowers of a plant may 

 appear at successive periods, extending over eight days, more or 

 less, in Indian corn ; seven days, more or less, in Timothy, several 

 days in oats and Avheat, and for a much longer period in branching 

 grasses like Eragrostis and Muhlenhergia. 



As an example of the fertilization of grasses, we find the fol- 

 lowing, by A. S. Wilson, in an admirable, illustrated paper on 

 *' Fertilization of Cereals," in the Gardeners' Chronicle, for 

 March 1874, and February, 1875 : 



''From the time at which the ears, or 

 part of the ears, of the four European 

 cereals, wheat, rye, barley and oats, 

 appear above the sheath, till the time of 

 flowering, the styles and the anthers 

 remain in nearly the same position. 

 During this time the filaments are of 

 such length as to place the lower ends of 

 the anthers in contact with the ujaper 

 part of the ovary, while the styles lie 

 embraced by the anthers, the whole being 

 straight and running in the same direcr 

 tion as the axis of the closed pales. If — (GaTdlners"chronicie) 

 a floret of two-rowed barley is held up between the eye and the 

 light before fertilization has taken place, the anthers will be seen 



Fig. 54.— Flowers of wheat, 

 a, young ; ?j, older. Enlarged. 



