CHAPTER XVI. 



Plan and Structure of the Flower and its Organs, 



175. Parts or Organs of the Flower. — Most showy flowers 

 consist, like those studied in the preceding chapter, of four 

 circles or sets of organs, the sepals, petals, stamens, and 

 pistils. The sepals, taken together, constitute the calyx, the 

 petals, taken together, constitute the corolla, Fig. 116.^ Some- 





Fig. 115.— The Parts of the Flower,' 

 cal., calyx ; cor.^ corolla ; stam., stamens ; pist., pistil. 



times it is convenient to have a word to comprise both calyx 

 and corolla; for this the term perianth is used. A flower which 

 contains all four of these sets is said to be complete. Since 

 the work of the flower is to produce seed, and seed-forming is 

 due to the cooperation of stamens and pistils, these are known 



1 The flower of the waterleaf or HyUrophylhtm, modified by the omission of the 

 hairs on the stamens, is here given because it shows so plainly the relation of the 

 parts. 



2 Hydrophyllum Canadense, with appendages in throat of corolla and liairs on 

 stamens omitted. 



