430 BOTANY. 



In cyclic flowers there are most frequently four or five whorls, viz. : 



1. The Calyx, composed of (mostly) greeu sepals. 



2. The Corolla, composed of (mostly) colored petals. 



3. (4.) The Andrceciitm, composed of one or two whorls of stamens. 

 4 or 5. The Gyn&cium, composed of carpels. 



These whorls usually contain definite numbers of organs in each ; in 

 many cases the numbers are the same for all the whorls of the flower 

 (isomerous flower) ; when the numbers are different the flower is said 

 to be heteromerous. 



The terms which denote these numerical relations are : monocycllc, 

 applied to a flower having only one cycle ; licydic, two cycles ; tricydic, 

 three cycles ; tetracyclie, four cycles ; penta yclic, five cycles, etc. ; 

 monomerous, applied to flowers each cycle of which contains one mem- 

 ber ; dimerous, two members ; trimerous, three members ; tetramerous, 

 four members ; pentamerous, five members. 



These relations can be briefly indicated by using symbols and con- 

 structing floral formulae, as follows : 



Ca 6 , Co 6 , An 5 , Gn 5 = a tetracyclie pentamerous flower ; 

 Ca 3 , Co 3 , An 3 + 3 , Gn 3 = a pentacyclic trimerous flower. 



Most commonly the members of one whorl alternate with those of 

 the whorla next above and below ; in a few cas.es, however, they are 

 opposite (or superposed) to each other. These relations may be indi- 

 cated by a modification of the floral formulae given above, as follows, 

 where the members are alternate . 



Gn 



An 



An 



Co 



Ca 



B 



When they are opposite the arrangement is as follows : 



Co 



B 



In both these formulas the position of the parts of the flower with 

 respect to the flowering axis is indicated by the position of the bract 

 B, which, is always on the anterior side, while the axis is always pos- 

 terior. 



When all the members on each whorl are equally developed, having 

 the same size and form, the flower may be vertically bisected in any 

 plane into two equal and similar halves; it is then actinomorphic 

 (= regular, and polysymmetrical). When the members in each whorl 



