Pistil Sentence Examples
The pistil consists of a single carpel with its ovary, style, stigma and solitary ovule or twin ovules.
A pistil is usually formed by more than one carpel.
Some of the flowers are often imperfect, the stamens or pistil being more or less aborted.
The pistil consists of one or more modified leaves, the carpels (or megasporophylls).
The method of pollination is to some extent governed by the distribution of the stamens and pistil.Advertisement
The pistil is placed on the receptacle r, at the extremity of the peduncle.
The pistil consists of several carpels, which are elevated on a stalk or gynophore prolonged from the receptacle.
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.
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.Advertisement
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.
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.
Sometimes they become adherent to the petals, or are epipetalous, and the insertion of both is looked upon as similar, so that they are still hypogynous, provided they are independent of the calyx and the pistil.
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.Advertisement
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.
In order that fertilization may be effected the pollen must be conveyed to the stigma of the pistil.
Under the term disk is included every structure intervening between the stamens and the pistil.
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 the first-mentioned case the terms carpel and pistil are synonymous.Advertisement
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.
The stamens are indefinite, and are inserted below the pistil (hypogynous).
When the carpels are united, as in the pear, arbutus and chickweed, the pistil becomes syncarpous.
The number of carpels in a pistil is indicated by the Greek numeral.
A flower with a simple pistil is monogynous; with two carpels, digynous; with three carpels, trigynous, &c.Advertisement
When the union is incomplete, the number of the parts of a compound pistil may be determined by the number of styles and stigmas; when complete, the external venation, the grooves on the surface, and the internal divisions of the ovary indicate the number.
When the pistil is formed by one carpel the inner margins unite and form usually a common marginal placenta, which may extend FIG.
When the pistil consists centa; s,withered style and of several separate carpels, or is stigma; c, persistent calyx.
This is particularly abundant when the pistil is ready for fertilization.
When in a compound pistil the style of each carpel is thus displaced, it appears as if the ovary were depressed in the centre, and the style rising from the depression in the midst of the carpels seems to come from the torus.
The style of a single carpel, or of each carpel of a compound pistil, may also be divided.
The stigma alternates with the dissepiments of a syncarpous pistil, or, in other words, corresponds with the back of the loculaments; but in some cases it would appear that half the stigma of one carpel unites with half that of the contiguous carpel, and thus the stigma is opposite the dissepiments, that is, alternates with the loculaments, as in the poppy.
The divisions of the stigma mark the number of carpels which compose the pistil.
The carpellary leaves are sometimes united in such a way as to leave an opening at the apex of the pistil, so that the ovules are exposed, as in mignonette.
When the pistil has reached a certain stage in growth it becomes ready for fertilization.
There are about 20 stamens, white with an orange head, clustered around a central green pistil with a yellow head.
Each flower has six stamens and a single pistil.
A nearly related form, which may be regarded as a sub-species, canescens, the grey poplar of the nurseryman, is distinguished from the true abele by its smaller, less deeply cut leaves, which are grey on the upper side, but not so hoary beneath as those of P. alba; the pistil has eight stigma lobes.
As with few exceptions the stamen represents a leaf which has been specially developed to bear the pollen or microspores, it is spoken of in comparative morphology as a microsporophyll; similarly the carpels which make up the pistil are the megasporophylls (see Angiosperms).
Their normal position is below the pistil, and when they are so placed (fig.64, a) upon the thalamus they are hypogynous.
A botanist notices that the bee flying with the pollen of a male flower to a pistil fertilizes the latter, and sees in this the purpose of the bee's existence.
A stamen is opposite each sepal, and in the centre of the flower is the rudiment of a pistil.
The pistil, which is above the rest of the members of the flower, consists of two carpels joined at their edges to form the ovary, which becomes two-celled by subsequent ingrowth of a septum from these united edges; a row of ovules springs from each edge.
The anthers shed their pollen into this groove, either of themselves or when the pistil is shaken by the insertion of the bee's proboscis.
The eggs are deposited in the ovary-wall, usually just below an ovule; after each deposition the moth runs to the top of the pistil and thrusts some pollen into the opening of the stigma.
The inflorescence is a very simple one, consisting of one or two male flowers each comprising a single stamen, and a female flower comprising a flask-shaped pistil.
The details of the structure of the flower show a wide variation; the flowers are often extremely simple, sometimes as in Arum, reduced to a single stamen or pistil.
The structure of the flower represents the simple type of monocotyledons, consisting of two whorls of petals, of three free parts each, six free stamens, and a consolidated pistil of three carpels, ripening into a three-valved capsule containing many winged seeds.
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.
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.
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.
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.
In a few cases two whorls of stamens are present, with three members in each, but generally only three are present; the pistil consists of three or two carpels, united to form an ovary bearing a corresponding number of styles and containing one ovule.
The pistil consists of a single carpel, opposite the pale in the median plane of the spikelet.
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."
In some plants the stamens are perfected before the pistil; these are called proterandrous, as in Ranunculus repens, Silene maritima, Zea Mays.
The length sometimes bears a relation to that of the pistil, and to the position of the flower, whether erect or drooping.
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.
The pistil is apocarpous, consisting of several distinct carpels, each with ovary, style and stigma.
The gynoecium or pistil is the central portion of the flower, terminating the floral axis.
In bisexual or hermaphrodite flowers, that is, those in which both stamens and pistil are present, though self-pollination might seem the obvious course, this is often prevented or hindered by various arrangements which favour cross-pollination.