s, the parts of the outer
circle represent the calyx; the next, corolla; within, stamens (here in
two circles of three each, and the cross-section is through the
anthers); in the centre, section of three ovaries joined into a compound
one of three cells.]

242. =Alternation of the successive Circles.= In these flowers the parts
of the successive circles _alternate_; and such is the rule. That is,
the petals stand over the intervals between the sepals; the stamens,
when of the same number, stand over the intervals between the petals; or
when twice as many, as in the Trillium, the outer set alternates with
the petals, and the inner set, alternating with the other, of course
stands before the petals; and the pistils alternate with these. This is
just as it should be on the theory that the circles of the blossom
answer to whorls of leaves, which alternate in this way. While in such
flowers the circles are to be regarded as whorls, in others they are
rather to be regarded as condensed spirals of alternate leaves. But,
however this may be, in the mind of a morphological botanist,

243. =Flowers are altered Branches=, and their parts, therefore, altered
leaves. That is, certain buds, which might have grown and lengthened
into a leafy branch, do, under other circumstances and to accomplish
other purposes, develop into blossoms. In these the axis remains short,
nearly as it is in the bud; the leaves therefore remain close together
in sets or circles; the outer ones, those of the calyx, generally
partake more or less of the character of foliage; the next set are more
delicate, and form the corolla, while the rest, the stamens and pistils,
appear under forms very different from those of ordinary leaves, and are
concerned in the production of seed. This view gives to Botany an
interest which one who merely notices the shape and counts the parts of
blossoms, without understanding their plan, has no conception of.

244. That flowers answer to branches may be shown, first, from their
position. As explained in the section on Inflorescence, flowers arise
from the same places as branches, and from no other; flower-buds, like
leaf-buds, appear either on the summit of a stem, that is, as a terminal
bud, or in the axil of a leaf, as an axillary bud. And, as the plan of a
symmetrical flower shows, the arrangement of the parts on their axis or
receptacle is that of leaves upon the stem.

245. That the sepals and petals are of the nature of