484 



BOTANY 



I'ART II 



adapted for distribution by the wind. In entomopliilous ilowers, 

 on the other hand, the exine is frequently sticky or provided with 

 spiny projections, and the pollen-grains are thus enabled to attach 



themselves better to the bodies 

 of the insect visitors. They also 

 differ from the pollen-grains of 

 the Gymnosperms in having more 

 or less numerous spots in the 

 wall prepared beforehand for the 

 emission of the pollen-tube (Figs. 

 428, 429). Various modifications 

 of the androecium result from 



Fio. 430. — Sambucus nigra. Longitudinal sec- 

 tion of flower. .<!, Ovule ; n, stigma. (After 



TsCHIRCe-OSTEBLE.) 



Fig. 431. — Transverse section of an ovary of 

 Delphinium Ajacis, showing ovule placed 

 horizontally, s, Ovule ; p, placenta ; o, 

 wall of ovary; r, vascular bundles, (x IS.) 



the cohesion and branching of the stamens, and will be described 

 in the special part. Sterile stamens which do not produce fertile 

 pollen are termed STAMINODES. 



The flower is terminated above by the gynaeceum (Fig. 430). 



A 



Fio. 432. — Transverse sections of ovaries. A,Lohdia; B, Dktpcnsia; C, Ithudoikndron ; 

 D, I'assiflora ; pi, placenta ; sa, ovules. (After Le Maout and Decaisne.) 



The CARPELS composing this may remain free and each give rise to a 

 separate fruit (APOCARPOUS gynaeceum), or they unite together to 

 form the ovary (sYNCARPOUS gynaeceum). The carpels, as a rule, 

 bear the ovules on their margins, on more or less evident outgrowths 



