The pistil consists of one or more modified leaves, the carpels (or megasporophylls).
Some of the flowers are often imperfect, the stamens or pistil being more or less aborted.
In some plants the stamens are perfected before the pistil; these are called proterandrous, as in Ranunculus repens, Silene maritima, Zea Mays.
The pistil or gynoecium occupies the centre or apex of the flower, and is surrounded by the stamens and floral envelopes when these are present.
In some Monocotyledons, Pistil and macrosporangium, is very similar to the process in Fertiliza- to the opening of the micropyle, into which the pollen- tion.
3, Barren pistil of male flower, enlarged.
The gynoecium or pistil is the central portion of the flower, terminating the floral axis.
- The pistil of Tobacco (Nicotiana Tabacum), consisting of the ovary o, containing ovules, the style s, and the capitate stigma g.
The pistil is placed on the receptacle r, at the extremity of the peduncle.
- Calyx and pistil of Fraxinella (Dictamnus Fraxinella).
The pistil consists of several carpels, which are elevated on a stalk or gynophore prolonged from the receptacle.
37 there are three divisions of the calyx, corolla and pistil, and six stamens in two rows.
In such circumstances, however, a flower has been called symmetrical, provided the parts of the other whorls are normal, - the permanent state of the pistil not being taken into account in determining symmetry.
The calyx and corolla consist of five parts, the stamens are ten in two rows, while the pistil has only two parts developed.
Obsolete calyx (c) of Madder (Rubia) adherent to the pistil, in the form of a rim.
The stamens and the pistil are sometimes spoken of as the essential organs of the flower, as the presence of both is required in order that perfect seed may be produced.
Hermaphrodite or bisexual flowers are those in which both these organs are found; unisexual or diclinous are those in which only one of these organs appears, - those bearing stamens only, being staminiferous or " male "; those having the pistil only, pistilliferous or " female."
For instance, in Primula and Linum some flowers have long stamens and a pistil with a short style, the others having short stamens and a pistil with a long style.
In other plants, but more rarely, the pistil is perfected before the stamens, as in Potentilla argentea, Plantago major, Coix Lachryma, and they are termed proterogynous.
The length sometimes bears a relation to that of the pistil, and to the position of the flower, whether erect or drooping.
Changes are produced in the whorl of stamens by cohesion of the filaments to a greater or less extent, while the anthers remain free; thus, all the filaments of the androecium may unite, forming a tube round the pistil, or a central bundle when the pistil is abortive, the stamens becoming monadelphous, as occurs in plants of the Mallow tribe; or they may be arranged in two bundles, the stamens being diadelphous, as in Polygala, Fumaria and Pea; in this case the bundles may be equal or unequal.
- Stamens and pistil of Sweet Pea (Lathyrus).
The anthers dehisce at different periods during the process of flowering; sometimes in the bud, but more commonly when the pistil is fully developed and the flower is expanded.
In the latter case individual stamens may move in succession towards the pistil and discharge their contents, as in Parnassia palustris, or the outer or the inner stamens may first dehisce, following thus a centripetal or centrifugal order.
- Pistil of Asclepias (a) with pollen-masses (p) adhering to the stigma (s).
- Male flower of Pellitory (Parietaria officinalis), having four stamens with incurved elastic filaments, and an abortive pistil in the centre.
In the first-mentioned case the terms carpel and pistil are synonymous.
In it no fruit is produced, and the pistil consists merely of sessile leaves, the limb of each being green and folded, with a narrow prolongation upwards, as if from the midrib, and ending in a thickened portion.
A pistil is usually formed by more than one carpel.
- Pistil of Broom (Cytisus) consisting of ovary o, style s, and stigma t.
The pistil is apocarpous, consisting of several distinct carpels, each with ovary, style and stigma.
The receptacle bearing the calyx is sometimes united to the pistil, and enlarges so as to form a part of the fruit, as in the apple, pear, &c. In these fruits the withered calyx is seen at the apex.
The stamens are indefinite, and are inserted below the pistil (hypogynous).
4, Pistil of female flower.
The pistil consists of a single carpel, opposite the pale in the median plane of the spikelet.
The flowers are regular and symmetrical, having five sepals, tapering to a point and hairy on the margin, five petals which speedily fall, ten stamens, and a pistil bearing five distinct styles.
The irregular flowers have five sepals united at the base, the dorsal one produced into a spurred development of the axis; of the five petals the two upper are slightly different and stand rather apart from the lower three; the eight stamens are unequal and the pistil consists of three carpels which form a fleshy fruit separating into three one-seeded portions.
Encloses the stamens and pistil, protecting them from rain and the attacks of unbidden polleneating insects.
5 is a spikelet of the female inflorescence, consisting of two outer glumes, the lower one ciliated, which enclose two florets - one (a) barren (sometimes fertile), consisting of a flowering glume and pale only, and the other (b) fertile, containing the pistil with elongated style.
Pistil with petaloid stigmas.
The carpel, or aggregate of carpels forming the pistil or gynaeceum, comprises an ovary containing one or more ovules and a receptive surface or stigma; the stigma is sometimes carried up on a style.
1, single spikelet; 2, single flower with awned plume and palea; 3, pistil; 4, grain.