CHAPTER YI 



REPRODUCTIVE ORGANS 



It -n-ill be rememljored tliat nutrition ami rejii-odnction 

 are tlie two great funoti(jus of plants. In (liscussintr 

 foliage leaves, stems, and roots, they were used as illustra- 



Ls their external relations 



tions of nutritive organs, so far 

 are concerned. AVe shall now 

 briefly study the reproductive 

 organs from the same point 

 of view, not describing the 

 processes of reproduction, but 

 some of the external relations. 

 7 1 . Vegetative multiplica- 

 tion. — Among the very lowest 

 plants no special organs of 

 reproduction are develojied. 

 but most plants have them. 

 There is a kind of reproduc- 

 tion by which a portion of 

 the parent body is set apart to 

 produce a new plant, as when 

 a strawberry' runner produces 

 a irew strawlierry plant, or 

 when a willow twig or a grape 

 cutting is planted and produces new plants, or when a potato 

 tuber (a suliterranean stem) produces new potato plants, or 

 when pieces of Begonia, leaves are used to start new ISegonias. 

 This is known as vegetative muItipIicatiiDt. a kind of repro- 

 duction which does not use special reproductive organs. 



A group of ..^poros : A, 

 spores from a corulnoii mold (a 

 fiiiiirii..;), which are so minuti^ and 

 lielit that ttiev are carried about by 

 the air : ]1. two spores from a com- 

 mon alga {Jlotlihj'), which can 

 swim by means of the hair-like 

 processes; C, the conspicuous dotted 

 cell is a spore developed b}- a com- 

 mon mildew (a fungus), ^^hich is 

 carried about by currents of air. 



