118 
THE FIRST BOOK OF BOTANY. 
Does Fig. 202 represent a symmetrical flower? 
Are the parts symmetrical in Fig. 203 ? 
When the parts of a flower are arranged in twos, 
or multiples of two, the symmetry is said to be dimer¬ 
ous or binary. Fig. 200. 
When the parts of the floral whorls are in threes, 
or multiples of three, the symmetry is trimerous or 
ternary . Fig. 201. 
When the parts are in fours, the symmetry is te - 
tramerous or quaternary . Fig. 202. 
When the parts are in fives, the symmetry is jpen- 
tamerous or quinary . 
If you have the botanical charts, look at the mag¬ 
nified flowers represented on them, and point out the 
symmetrical ones, naming the kind of symmetry they 
exhibit. Then examine your living specimens. These 
will, of course, vary with the season. We will sup¬ 
pose, for example, that you have the pea, morning- 
glory, violet, portulaca, buttercup, Saint-John’s-wort, 
hollyhock, potato-blossom, evening primrose, lily, etc. 
Decide which are symmetrical and which are unsym- 
metrical, placing the two kinds apart. Re-examine 
the symmetrical ones, and tell which have binary sym¬ 
metry, which ternary, which quaternary, and which 
quinary. 
EXERCISE XXXVII. 
Complete and Incomplete Flowers • 
The collection of flowers that in the previous ex¬ 
ercise were separated into symmetrical and unsym- 
metrical ones, may now be rearranged, separating the 
