xxvi BOTANY. 
flowers); in some cases they are arranged in spirals, with, how- 
ever, a distinct separation of the different groups of organs 
(hemicyclic flowers); in still other cases the 
arrangement is spiral throughout, with no 
separation of the groups of organs (acyclic 
flowers). 
In cyclic flowers there are most frequently 
four or five whorls, viz. (Fig. XXI): 
1. The Calyx, composed of (mostly) grecn 
sepals. 
2. The Corolla, composed of (mostly) col- 
ored petals, The calyx and corolla may be 
spoken of collectively as the Perianth. 
This term is also uSed when but one whorl 
of floral leaves, or a portion of it only, is 
present. — 
3. (4.) The Andrecium, composed of one 
Fie, XXI.—Diagram to 
show the four floral 
whorls; the lowermost 
the sepals, composing the 
calyx; the next the petals, 
composing the corolla; 
the next the stamens,com- 
posing the androecium; 
the uppermost the pistils, 
or two whorls of stamens, 
4 or 5. The Gynwcium, composed of the 
pistil or pistils. 
These whorls usually contain definite 
numbers of organs in each; in many cases 
the numbers are the same for all the whorls 
composing thegyncecium. of the fluwer (ésomerous flower); when the 
numbers are different the flower is said to be heteromerous, 
The terms which denote these numerical relations are: monocyclic, 
applied to a flower having only one cycle; bicyclic, two cycles; 
tricyclic, three cycles; tetracyclic, four cycles; pentacyclic, five cycles, 
etc.; monomerous, applied to flowers each cycle of which con- 
tains one member; dimerous, two members; frimerous, three 
members; tetramerous, four members; pentamerous, five mem- 
bers, etc. ete. 
Floral Formule.—These relations can be briefly indicated by 
using symbols and constructing floral formule, as follows: 
Cas, Cos, Ans, Gns =a tetracyclic pentamerous flower; 
Cas, Cos, Ans+s, Gns = a pentacyclic trimerous flower. 
Most commonly the members of one whorl alternate with those 
of the whorls next above and below; in a few cases, however, they 
are opposite (or superposed) to each other. 
Floral Diagrams.—These relations may be indicated by a modi- 
