Descriptive Biology 



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anther the pollen grains are formed, and these when ripe 

 are scattered by the wind or carried by insects to another 

 flower, where, lighting upon its stigmas, they germinate and 

 send fine tubes down through the styles to reach the ovaries 

 at their base. Through these tubes pass the male nuclei 

 formed within the pollen grain, which unite with the female 

 nuclei within the ovaries, the pollen tube representing the 

 last remnant of the body of the sexual plant in lower forms. 

 Similarly there are contained within the ovary, beside the 



REPRODUCTION OF PLANTS 



Left: A phlox blossom showing flower parts. Ca, calyx; co, corolla; 

 sta, stamens; sti, stigma; sty, style. Original. 



Eight: Alternation of generations in 1, fern, showing the sexual form 

 or prothallus bearing the asexual fern, fe; and 2, moss,, showing the 

 spore capsule, c. 



female nucleus, several nuclei, which represent the body of 

 the female sexual plant in mosses or in ferns. 



The moss plant is the sexual form, which bears the egg and 

 sperm producing organs. From the egg, after fertilization 

 in the ovary springs a slender stalk bearing a capsule at its 

 summit. When this is ripe it bursts, casting forth the tiny 

 spores, which generating give rise in turn to the sexual moss 

 plant. Similar conditions obtain in the liverworts. In 

 these forms therefore the gametophyte or sexual plant is 

 the chief generation, the sporophyte or asexual form the 

 smaller, secondary one. 



In ferns the reverse is the case. If one examine the under- 



