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. 115." Some- 
\ 
oe 
Fic. 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 codperation of stamens and pistils, these are known 
1 The flower of the waterleaf or Hydrophyllum, 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 hairs on 
stamens omitted. 
