THE FLOWER. 39 



plied to the axis of a flower-cluster when it is disk-like or 

 short, so that the flowers are crowded into a head. 



3. The purpose of the flower is the production of seed. 

 Four distinct parts may be present, each having a distinct 

 function to perform. In a flower such as the Buttercup, Crab- 

 Apple, Morning Glory, Phlox, etc. there will be found as the 

 outermost part, a calyx, or cup-like portion. This consists of 

 several parts, either distinct or united, which more or less re- 

 semble ordinary foliage leaves. Each leaf or portion of the 

 calyx is called a sepal. Within this whorl of leaves forming 

 the calyx is a second whorl, either of distinct or more or less 

 united parts, called the corolla. This is commonly the most 

 showy part of the flower. Its component parts are called 

 petals, and they usually depart farther from the ordinary 

 form and texture of foliage leaves than do the sepals. 



4. Within the corolla are slender bodies called stamens. 

 They sometimes revert to petals or sepals, showing that they 

 are also modified leaves. These organs are sometimes exces- 

 sively numerous; and when few are rarely less in number 

 than the parts of the corolla or calyx. Within these and occu- 

 pying the central part of the flower, are the pistils; in the 

 lower enlarged part of which, called the ovary, the seeds are 

 produced. The pistils, like the stamens, may be numerous, 

 but are very often fused together or reduced to one. There 

 can be no production of seed without both stamens and pistils, 

 and for this reason they are together called the essential organs 

 of the flower. The calyx and corolla may or may not be 

 present without directly influencing the production of seed. 

 They are called the perianth (Gr. peri, around ; anthos, flower), 

 a term that is used especially when the sepals and petals more 

 or less closely resemble each other. 



5. A flower with the four parts present is called a complete 

 flower ; but if one or more of the parts are absent, the flower 

 is said to be incomplete. If the essential organs are present 

 it is called a perfect flower. Those with stamens but no pis- 

 tils, called staminate flowers, and those with pistils but no 

 stamens, called pistillate flowers, are imperfect. If the several 



