ne general plan, but with almost
infinite variations, and many disguises. This common plan is best
understood by taking for a type, or standard for comparison, some
_perfect_, _complete_, _regular_, and _symmetrical_ blossom, and one as
simple as such a blossom could well be. Flowers are said to be

_Perfect_ (_hermaphrodite_), when provided with both kinds of essential
organs, i. e. with both stamens and pistils.

_Complete_, when, besides, they have the two sets of floral envelopes,
namely, calyx and corolla. Such are completely furnished with all that
belongs to a flower.

_Regular_, when all the parts of each set are alike in shape and size.

_Symmetrical_, when there is an equal number of parts in each set or
circle of organs.

240. Flax-flowers were taken for a pattern in Section II. 16. But in
them the five pistils have their ovaries as it were consolidated into
one body. Sedum, Fig. 222, has the pistils and all the other parts free
from such combination. The flower is perfect, complete, regular, and
symmetrical, but is not quite as simple as it might be; for there are
twice as many stamens as there are of the other organs. Crassula, a
relative of Sedum, cultivated in the conservatories for winter
blossoming (Fig. 224) is simpler, being _isostemonous_, or with just as
many stamens as petals or sepals, while Sedum is _diplostemonous_,
having double that number: it has, indeed, two sets of stamens.

[Illustration: Fig. 224. Flower of a Crassula. 225. Diagram or
ground-plan of same.]

241. =Numerical Plan.= A certain number either runs through the flower
or is discernible in some of its parts. This number is most commonly
either five or three, not very rarely four, occasionally two. Thus the
_ground-plan_ of the flowers thus far used for illustration is five.
That of Trillium (Fig. 226, 227) is three, as it likewise is as really,
if not as plainly, in Tulips and Lilies, Crocus, Iris, and all that
class of blossoms. In some Sedums all the flowers are in fours. In
others the first flowers are on the plan of five, the rest mostly on the
plan of four, that is, with four sepals, four petals, eight stamens (i.
e. twice four), and four pistils. Whatever the ground number may be, it
runs through the whole in symmetrical blossoms.

[Illustration: Fig. 226. Flower of a Trillium; its parts in threes.]

[Illustration: Fig. 227. Diagram of flower of Trillium. In this, as in
all such diagrams of cross-section of blossom