stil is a carpel. Each component flower-leaf of
a compound pistil is likewise a carpel. When a flower has two or more
pistils, these of course are simple pistils, that is, separate carpels
or pistil-leaves. There may be only a single simple pistil to the
flower, as in a Pea or Cherry blossom (Fig. 271); there may be two such,
as in many Saxifrages; or many, as in the Strawberry. More commonly the
single pistil in the centre of a blossom is a compound one. Then there
is seldom much difficulty in ascertaining the number of carpels or
pistil-leaves that compose it.

306. =The Simple Pistil=, viewed morphologically, answers to a
leaf-blade with margins incurved and united where they meet, so forming
a closed case or pod (the ovary), and bearing ovules at the suture or
junction of these margins: a tapering upper portion with margins
similarly inrolled, is supposed to form the style; and these same
margins, exposed at the tip or for a portion of the length, become the
stigma. Compare, under this view, the three accompanying figures.

[Illustration: Fig. 323. An inrolled small leaf, such as in
double-flowered Cherry blossoms is often seen to occupy the place of a
pistil.]

[Illustration: Fig. 324. A simple pistil (of Isopyrum), with ovary cut
across; the inner (ventral) face turned toward the eye: the ovules seem
to be borne on the ventral suture, answering to leaf-margins: the stigma
above seen also to answer to leaf-margins.]

[Illustration: Fig. 325. Pod or simple pistil of Caltha or
Marsh-Marigold, which has opened, and shed its seeds.]

307. So a simple pistil should have a one-celled ovary, only one line of
attachment for the ovules, a single style, and a single stigma. Certain
variations from this normal condition which sometimes occur do not
invalidate this morphological conception. For instance, the stigma may
become two-lobed or two-ridged, because it consists of two leaf-margins,
as Fig. 324 shows; it may become 2-locellate by the turning or growing
inward of one of the sutures, so as to divide the cavity.

308. There are two or three terms which primarily relate to the parts of
a simple pistil or carpel, and are thence carried on to the compound
pistil, viz.:--

VENTRAL SUTURE, the line which answers to the united margins of the
carpel-leaf, therefore naturally called a suture or seam, and the
ventral or inner one, because in the circle of carpel-leaves it looks
inward or to the centre of the flower.

DOR