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SYMMETRY OF THE FLOWER. 3038 
218), and the flower itself to a branch the internodes of which 
are but slightly developed, so that all its parts are situated in 
nearly the same plane ; and, as flower-buds are thus analogous 
to leaf-buds, their parts are also necessarily subject to similar 
laws of development and arrangement, and hence a knowledge 
of the latter gives the clue to that of the former. 
The symmetrical arrangement of the parts of the flower 
arising from their being homologous parts with the leaves, will 
now be described, together with the various causes which inter- 
fere to prevent or disguise it. 
Section 8. SyMMETRY OF THE FLOWER. 
THE term symmetry has been variously understood by differ- 
ent botanists. As properly applied, a symmetrical flower is one 
in which each whorl of organs hasan equal number of parts ; or 
where the parts of one whorl are multiples of those of another. 
Thus, in some species of Crassula (fig. 785), we have a sym- 
Fie. 785. Fic. 786. 
Fig. 785. Flower of Crassula rubens. c,c. Sepals. p, p. Petals. e, e, e. 
Stamens. 0,0. Carpels, at the base of each of which is seen « scale, a, a. 
— Fig. 786. Flower of a Sedum. 
metrical flower composed of five sepals, five petals, five stamens, 
and five carpels ; in Sedum (fig. 786) we have five sepals, five 
petals, ten stamens in two rows, and five carpels ; in the Flax 
we have five sepals, five petals, five stamens, and five carpels, 
each of which is partially divided into two by a spurious dis- 
sepiment (fig. 618); in the Circea (fig. 787) we have two organs 
in each whorl ; in the Rue (figs. 611 and 579) we have four or 
five sepals, four or five petals, eight or ten stamens, and a four- 
or five-lobed pistil; and in the Iris there are three organs in 
each whorl. All the above are therefore symmetrical flowers. 
When the number of parts in each whorl does not correspond, 
or when the parts of a whorl are not multiples of one another, 
the flower is wisymmetrical, as in Verbena, where the calyx and 
corolla have five parts in each whorl, and the andrecium and 
gyncecium only four.. 
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