Flower | Article about flower by The Free Dictionary Flower | Article about flower by The Free Dictionary Also found in: Dictionary , Thesaurus , Medical , Legal , Idioms , Wikipedia . flower, name for the specialized part of a plant containing the reproductive organs, applied to angiosperms only. A flower may be thought of as a modified, short, compact branch bearing lateral appendages. Like twigs, flowers develop from buds, and the basic floral parts (sepal, petal, stamen, and carpel) are in actual fact greatly modified leaves. A typical flower is a concentric arrangement of these parts attached at their base to the receptacle, the tip of the stem. Outermost is a whorl of leaflike green sepals (the calyx) encircling a whorl of usually showy, colored petals (the corolla). Within the corolla the stamens, bearing anther sacs full of pollen pollen, minute grains, usually yellow in color but occasionally white, brown, red, or purple, borne in the anther sac at the tip of the slender filament of the stamen of a flowering plant or in the male cone of a conifer. ..... Click the link for more information.

, surround the central carpels (ovary). Inside the ovary at the base of the pistil are the ovules, containing the female sex cells; after fertilization of the egg, the ovule becomes the seed seed, fertilized and ripened ovule, consisting of the plant embryo, varying amounts of stored food material, and a protective outer seed coat. Seeds are frequently confused with the fruit enclosing them in flowering plants, especially in grains and nuts. ..... Click the link for more information. and the ovary becomes the fruit fruit, matured ovary of the pistil of a flower, containing the seed. After the egg nucleus, or ovum, has been fertilized (see fertilization) and the embryo plantlet begins to form, the surrounding ovule (see pistil) develops into a seed and the ovary wall (pericarp) around the ..... Click the link for more information. . The ovary and stamens are termed essential flower parts, the petals and sepals accessory parts. The number and arrangement of the floral organs vary considerably among the many families and orders of plants and are used in the classification of plants; they also indicate the degree of evolution of the plant.

In general, the higher a plant is on the evolutionary scale, the greater is the flower's complexity. The basic number of parts differs from class to class and from family to family; in monocotyledonous plants the parts generally occur in groups of three or in multiples of three, and in dicotyledons more often in groups of two, four, and five. Flowers may be staminate (lack carpels), carpellate, or both; staminate and carpellate flowers may appear on the same plant, on separate plants, or in the same inflorescence. One type of inflorescence, characteristic of the parsley family, is the umbel, in which the tiny florets are borne on separate stalks radiating out from the stem tip. Sometimes the parts serve unusual purposes: the true flowers of the dogwood and the poinsettia are inconspicuous, and the showy "petals" are really modified leaves called bracts. In the jack-in-the-pulpit the florets are clustered on a spike canopied by a large bract, the spathe; the hood of the lady's-slipper, on the other hand, is a modified sterile stamen.

Grass inflorescences are tiny spikelets sheathed by protective scales called glumes (the chaff or grain). Flowers have been cultivated and bred for their beauty and their perfume from earliest times and have accumulated a vast and intricate treasury of symbolic associations derived from legend and folklore. Individual flowers have been celebrated in heraldry ( rose rose, common name for some members of the Rosaceae, a large family of herbs, shrubs, and trees distributed over most of the earth, and for plants of the genus Rosa, the true roses. ..... Click the link for more information. ), in religion (lotus), and in politics ( violet violet, common name for some members of the Violaceae, a family of chiefly perennial herbs (and sometimes shrubs, small trees, or climbers) found on all continents. Violets, including the genus Viola ..... Click the link for more information. ) and have become emblems for many countries, including Switzerland (edelweiss), France (fleur-de-lis), Scotland (thistle), the Netherlands (tulip), and the United States (see state flowers state flowers.

Each state of the United States has designated, usually by legislative action, one flower as its floral emblem; the rose has been designated by Congress as the national flower of the United States. ..... Click the link for more information. ). Bibliography See S. Buchmann, The Reason for Flowers (2015). Flower A higher plant's sexual apparatus in the aggregate, including the parts that produce sex cells and closely associated attractive and protective parts (Fig. 1). “Flower” as used in this article will be limited, as is usual, to the angiosperms, plants with enclosed seeds and the unique reproductive process called double fertilization. In its most familiar form a flower is made up of four kinds of units arranged concentrically. The green sepals (collectively termed the calyx) are outermost, showy petals (the corolla) next, then the pollen-bearing units (stamens, androecium), and finally the centrally placed seed-bearing units (carpels, gynoecium). This is the “complete” flower of early botanists, but it is only one of an almost overwhelming array of floral forms.

One or more kinds of units may be lacking or hard to recognize depending on the species, and evolutionary modification has been so great in some groups of angiosperms that a flower cluster (inflorescence) can took like a single flower. Flower structure, median longitudinal section Flora diversity Most botanical terms are descriptive, and a botanist must have a large store of them to impart the multiformity of flowers. The examples that follow are only a smattering. An extra series of appendages alternating with the sepals, as in purple loosestrife, is an epicalyx. A petal with a broad distal region and a narrow proximal region is said to have a blade and claw: the crape myrtle has such petals. The term perianth, which embraces calyx and corolla and avoids the need to distinguish between them, is especially useful for a flower like the tulip, where the perianth parts are in two series but are alike in size, shape, and color. The members of such an undifferentiated perianth are tepals.

When the perianth has only one series of parts, however, they are customarily called sepals even if they are petallike, as in the windflower. A stamen commonly consists of a slender filament topped by a four-lobed anther, each lobe housing a pollen sac. In some plants one or more of the androecial parts are sterile rudiments called staminodes: a foxglove flower has four fertile stamens and a staminode. Carpellode is the corresponding term for an imperfectly formed gynoecial unit. A gynoecium is apocarpous if the carpels are separate (magnolia, blackberry) and syncarpous if they are connate (tulip, poppy). Or the gynoecium may regularly consist of only one carpel (bean, cherry). A solitary carpel or a syncarpous gynoecium can often be divided into three regions: a terminal, pollen-receptive stigma; a swollen basal ovary enclosing the undeveloped seeds (ovules); and a constricted, elongate style between the two.

The gynoecium can be apocarpous above and syncarpous below; that is, there can be separate styles and stigmas on one ovary (wood sorrel). Placentation: (a) parietal, (b) axile, and (c) free central Every flower cited so far has a superior ovary: perianth and androecium diverge beneath it (hypogyny). If perianth and androecium diverge from the ovary's summit, the ovary is inferior and the flower is epigynous (apple, banana, pumpkin). A flower is perigynous if the ovary is superior within a cup and the other floral parts diverge from the cup's rim (cherry). A syncarpous ovary is unilocular if it has only one seed chamber, plurilocular if septa divide it into more than one. The ovules of a plurilocular ovary are usually attached to the angles where the septa meet; this is axile placentation, a placenta being a region of ovular attachment.

There are other ways in which the ovules can be attached—apically, basally, parietally, or on a free-standing central placenta—each characteristic of certain plant groups (Fig. 2). The term bract can be applied to any leaflike part associated with one or more flowers but not part of a flower. Floral bracts are frequently small, even scalelike, but the flowering dogwood has four big petallike bracts below each flower cluster. The broad end of a flower stalk where the floral parts are attached is the receptacle. The same term is used, rather inconsistently, for the broad base bearing the many individual flowers (florets) that make up a composite flower like a dandelion or a sunflower. Sexuality A plant species is diclinous if its stamens and carpels are in separate flowers. A diclinous species is monoecious if each plant bears staminate and carpellate (pistillate) flowers, dioecious if the staminate and carpellate flowers are on different plants.

The corn plant, with staminate inflorescences (tassels) on top and carpellate inflorescences (ears) along the stalk, is monoecious. Hemp is a well-known dioecious plant. Nectaries Flowers pollinated by insects or other animals commonly have one or more nectaries, regions that secrete a sugar solution. A nectary can be nothing more than a layer of tissue lining part of a floral tube or cup (cherry), or it can be as conspicuous as the secretory spur of a nasturtium or a larkspur. It can be a cushionlike outgrowth at the base of a superior ovary (orange blossom) or atop an inferior ovary (parsley family). Gladiolus and a number of other monocotyledons have septal nectaries, deep secretory crevices where the carpels come together. Substances that give off floral odors—essential oils for the most part—ordinarily originate close to the nectar-producing region but are not coincident with it.

Production by the epidermis of perianth parts is most common, but in some species the odor emanates from a more restricted region and may even come from a special flap or brush. Most insect-pollinated plants have visual cues, some of them outside the human spectral range, as well as odor to bring the pollinators to the flowers and guide them to the nectar. See Secretory structures (plant) Inflorescence Inflorescence structure, the way the flowers are clustered or arranged on a flowering branch, is almost as diverse as floral structure. To appreciate this, one need only contrast the drooping inflorescences (catkins) of a birch tree with the coiled flowers of a forget-me-not or with the solitary flower of a tulip. In some cases one kind of inflorescence characterizes a whole plant family. Queen Anne's lace and other members of the parsley family (Umbelliferae) have umbrellalike inflorescences with the flower stalks radiating from almost the same point in a cluster.

The stalkless flowers (florets) of the grass family are grouped into clusters called spikelets, and these in turn are variously arranged in different grasses. Flowers of the arum family (calla lily, jack-in-the-pulpit), also stalkless, are crowded on a thick, fleshy, elongate axis. In the composite family, florets are joined in a tight head at the end of the axis; the heads of some composites contain two kinds, centrally placed florets with small tubular corollas and peripheral ray florets with showy, strap-shaped corollas (the “petals” one plucks from a daisy). See Inflorescence Anatomy Some of the general anatomical features of leaves can be found in the floral appendages. A cuticle-covered epidermis overlies a core of parenchyma cells in which there are branching vascular bundles (solitary bundles in most stamens). Sepal parenchyma and petal parenchyma are often spongy, but palisade parenchyma occurs only rarely in flowers and then only in sepals.

As in other parts of the plant, color comes mostly from plastids in the cytoplasm and from flavonoids in the cell sap. Cells of the petal epidermis may have folded side walls that interlock so as to strengthen the tissue. In some species the outer walls of the epidermis are raised as papillae; apparently, this is part of the means of attracting pollinators, for the papillae are light reflectors. Stamen As a stamen develops, periclinal divisions in the second cell layer of each of its four lobes start a sequence that will end with the shedding of pollen. The first division makes two cell layers. The outer daughter cells give rise to the wall of the pollen sac, and the inner ones are destined to become pollen after further divisions. When mature, a pollen sac typically has a prominent cell layer just below a less distinctive epidermis. The inner wall and the side walls of an endothecium cell carry marked thickenings, but the outer wall does not. Splitting of the ripe anther is due partly to the way in which these differentially thickened walls react to drying and shrinking and partly to the smaller size of the cells along the line of splitting.

See Pollen Carpel Like other floral parts, a carpel is made up of epidermis, parenchyma, and vascular tissue. In addition, a carpel commonly has a special tissue system on which pollen germinates and through which, or along which, pollen tubes are transmitted to the ovules. Most angiosperms have solid styles, and the transmitting tissue is a column of elongate cells whose softened walls are the medium for tubal growth. The epidermis at the stigmatic end of a carpel usually changes to a dense covering of papillae or hairs; the hairs can be unicellular or pluricellular, branched or unbranched. In taxa with hollow styles, the transmitting tissue is a modified epidermis running down the stylar canal. There are two kinds of receptive surfaces, and they are distributed among the monocotyledons and the dicotyledons with taxonomic regularity. One kind has a fluid medium for germinating the pollen, and the other has a dry proteinaceous layer over the cuticle. The proteins of the dry stigmas have a role in the incompatibility reactions that encourage outbreeding.

Ovule Ovule development usually takes place as the gynoecium forms, but it may be retarded when there is a long interval between pollination and fertilization (oaks, orchids). A typical ovule has a stalk (funiculus), a central bulbous body (nucellus), and one or two integuments (precursors of seed coats), which cover the nucellus except for a terminal pore (micropyle). Orientation of the ovule varies from group to group. It can be erect on its stalk or bent one way or another to differing degrees. There are also taxonomic differences in the extent to which the ovule is vascularized by branches from the gynoecial vascular system. See Fruit , Reproduction (plant) Flower a short, limited-in-growth reproductive shoot that performs the functions of microsporogenesis, megasporogenesis, pollination (effected by pollen carrier-agents), fertilization, embryonic development, and fruit formation. The flower is borne at the end of a main or lateral stem. The peduncle, the part of the stem that bears the flower, is usually leafless.

Often it is very short and barely visible; in this case the flower is said to be sessile, or attached. The peduncle becomes the short axis of the flower, which is called the flower receptacle, or torus. The variously shaped receptacle is usually broader than the peduncle and is characterized by barely noticeable internodes. Its nodes bear all the various parts of the flower: the sterile sepals and petals and the fertile stamens and carpels. The sepals, which together form the calyx, usually serve as protective organs of the flower, especially before blooming; they often also function as supplementary organs of photosynthesis. The sepals often become petallike, taking on the functions of petals (for example, in Clematis). In some instances, through the process of evolution, the sepals have concresced into a synsepalous calyx. The petals, which serve to attract pollinators, are collectively known as the corolla. The calyx and the corolla together make up the perianth. When the flower has both a calyx and a corolla, the perianth is said to be double.

A simple perianth is one in which the petals are absent or in which there are no marked differences between the calyx and the corolla. In the center of the flower are located the stamens and carpels. The stamens are microsporophylls both in function and in origin. The most primitive ones, as seen in a number of representatives of the families Magnoliaceae and Winteraceae, consist of a broad ribbonlike membrane equipped with four linear microsporangia that are approximate in pairs and that are more or less embedded in the tissue of the membrane. In the course of evolution the stamens gradually became differentiated into the filament and the anther, which consists of two halves joined by a continuation of the filament. The stamens are known collectively as the androecium. The filaments often concresce together or with elements of the perianth or carpels. Sometimes the stamens concresce together by both the filaments and anthers or by the anthers only. The carpels consist of highly modified and specialized megasporophylls.

A single carpel is often called a simple pistil (the term “pistil” is used in various senses, often creating confusion). The most primitive type of carpel is retained in the genera Degeneria (family Degeneriaceae) and Tasmania (family Winteraceae). It consists of a short stalk and a relatively thin adaxially folded (conduplicate) membrane; externally it strongly resembles the conduplicate leaves folded into the bud. Along the carpel pass three conducting bundles (veins), of which the middle or dorsal one branches profusely. Between the middle and lateral veins are numerous ovules. In the early stages of development the margins of the carpels of Degeneria almost do not touch each other; protection of the ovules during flowering is ensured by the proximity of the broad lateral parts of the carpel, which are located between the carpel’s margins and placentas. These approximate internal surfaces concresce only after flowering, that is, during fruit development. The most diverse stages of concrescence are observed in other representatives of Winteraceae. In all flowering plants the carpel has a special glandular tissue, called the stigma, that serves to capture pollen.

In Degeneria and Tasmania the stigma is primitive and extends the entire length of the carpel. The upper part of the carpel usually extends into a slender, sterile columnar process, which supports the stigma above the ovary—the fertile part of the carpel—and serves as a passageway to the pollen tube. This specialized process is called the style or the stylodium (in which case the term “style” is only used in reference to concresced stylodia). In the early stages of evolution, the style is characterized by a descending stigma; in later stages the stigma gradually becomes localized at the top. The aggregate of carpels in the flower is called the gynoecium. The most primitive types of gynoecia with free carpels are called apocarpous; such gynoecia characterize Magnolia, Ranunculus, and Paeonia. In the process of evolution the carpels gradually concresced among themselves, and from the apocarpous gynoecium there emerged the coenocarpous gynoecium, in which the stylodia are free, or concresced to form the style.

The evolution of both the coenocarpous and apocarpous gynoecia was usually accompanied by a decrease in the number of carpels and, in most cases, in the number of ovules. An extreme form is the pseudomonomerous gynoecium, in which a single carpel is fertile and completely developed (as seen in elm, mulberry, nettle, and hemp). Most flowers have nectaries—special excretory organs for the production of nectar. Nectaries originated in the most diverse forms in the evolution of flowering plants and on the most diverse morphological bases, that is, on the most diverse parts of the flower. Primitive types of flowers are characterized by a relatively long receptacle, but in some cases, for example, in Myosurus and some Magnolia, there is a greatly elongated receptacle of secondary origin. In the process of evolution there has been a gradual shortening of the receptacle, as a result of which the flower parts have grown closer together and the initial spiral formation has changed to a cyclic one. The parts of a cyclic flower are usually arranged in whorls; less commonly, they are opposite.

Cyclic flowers are found more frequently than spiral ones. In an intermediate position are spirocyclic flowers, such as those of Ranunculus. Primitive flowers are actinomorphic (regular); that is, they can be divided by a vertical plane passing through the symmetrical axis into equal halves in no less than two directions. Owing to the biology of pollination, actinomorphic flowers gave rise to zygomorphic (irregular) ones, which can be divided into two halves only in a single direction (for example, the blossom of the sweet pea or snapdragon). In contrast to actinomorphic and zygomorphic flowers, which are both symmetrical, there are also asymmetrical flowers, which cannot be divided into two equal halves by a plane of symmetry (for example, cannas). Flowers may be bisexual or unisexual. Unisexual flowers originated from bisexual ones as a result of the reduction of the stamens in some cases and of the carpels in others. Unisexual flowers often retain the rudiments of stamens and carpels. It is conjectured that the flower is descended from the reproductive shoots of the supposed ancestors of flowering plants—seed ferns.

As a result of shortening, the shoot axis was converted into a receptacle. Simplification of the segmented microsporophylls and megasporophylls resulted in the simple unbranched stamens and carpels of flowering plants. (The hypothesis that the flower is descended from the strobile of Cycadaceae, Gnetaceae, or Bennettitaceae is improbable.) The evolution of the flower, like the evolution of the strobiles of various groups of gymnosperms, set off in various directions. Thus, current theories are based on the proposition that the fundamental parts of the flower—the stamens and carpels—are descended from the sporebearing organs of the ancestors of flowering plants. It is difficult to say with certainty whether these primitive spore cases were somewhat rounded or flat or whether they were achlorophyllous or green. It is most probable that they consisted of flat and more or less simplified, possibly lobular, sporophylls, which, especially if they were megasporophylls, probably partially performed the function of photosynthesis. REFERENCES Flowers (dreams) When we look at flowers, most of us feel some joy and vitality.

At the very least, we appreciate their beauty and see their value. Flowers are beautiful and in our dreams they could represent the simplest feelings of contentment or the deepest feelings of spiritual completeness. A circular flower is a friendly sign that could be the “mandala” symbol or the symbol of wholeness that represents the “psychic center of the personality.” Additionally, the colors could symbolize the psychic centers in our bodies called chakras. Flowers also represent hope and positive growth, along with simplicity, innocence, and possibly virginity. Four Whorls: The Parts of a Flower and Their Functions The Four Whorls of a Flower The parts and functions of a flower are much more detailed than they might appear at first glance. If you look at a flower from the top, you will be able to distinguish between four "whorls," or circular sections that share a common center. The outer whorl is called the calyx, and consists of the sepals. The next whorl is the corolla, and consists of the petals. The two innermost whorls are the stamens and the carpels, and those contain the male and female reproductive parts of the flower respectively.

slide 2 of 8 Whorl #1: The Calyx The calyx, which is the outermost whorl of a flower, protects the inner whorls, especially when the flower is in its bud state. The calyx is made up of sepals, which are two small green structures at the flower's base that look like tiny leaves. slide 3 of 8 Whorl #2: The Corolla The second whorl of the flower is the corolla, which is composed of the flower's petals. The petals serve two purposes: to protect the reproductive organs of the flower and to attract pollinators. Because of this second purpose, they are usually brightly colored and scented so that animals and insects will come close to them and move around the flower's pollen. The first two whorls of the flower -- the calyx and the corolla -- are collectively called the perianth. slide 4 of 8 Whorl #3: The Stamens The third whorl of a flower is the stamen, the male reproductive part. The stamen is made of a thin vertical thread-like structure called a filament topped with a circular or oblong structure called an anther.

The anther produces pollen, which is the male contribution to the reproduction process in plants . slide 5 of 8 Whorl #4: The Carpels At the center of the flower is the fourth whorl -- the carpels, which contain the pistil of the flower. The pistil is the plant's female reproductive organ, which is composed of three parts: the ovary, the style, and the stigma. The ovary contains the eggs, or ovules, of the plant, and when the ovules are fertilized, the ovary sometimes turns into a fruit to house the seed. The top of the ovary leads to a vertical structure called a style, which supports the stigma. The stigma catches grains of pollen that the wind or pollinators disperse, and the pollen grains travel down the style to the ovary. slide 6 of 8 Other Parts Their Functions Other, less commonly defined parts of a flower include the pedicel, or the stalk of the flower; the nectary, which secretes nectar; and the floral axis, a term which describes the section of the flower containing the four whorls.

Understanding these lesser-known parts of a flower and their functions is an important part of understanding why a flower is an important part of a plant. slide 7 of 8 NBII. "How Does That Flower Work?" Memorial University. "Molecular Biology of Flower Development." slide 8 of 8 Flower description glossary Terms describing flower anatomy Classical angiosperm phylogeny is based mainly on flower anatomy, and in particular, the arrangement and form of the principle parts. The fruiting body is used as well, but its structure is often apparent in the flowers. More recently, genetic studies have been employed to determine the relationship of various botanical groups to each other. Many parts of the old classification system have proven more or less consistent with these studies, but there have also been a large number of changes, even to large and well studied groups. The changes to the classical system have been far more extensive than in the animal kingdom, where the classical, anatomy-based phylogeny has held up remarkably well. As a result, botanical nomenclature has been undergoing a bit of a revolution in the last two decades, and the process (as of 2009) is still ongoing.

A community known as the Angiosperm Phylogeny Group or APG has provided some centrality to this process, but there are many areas where no consensus has been reached. Botany has always been prone to what might be termed "vanity species" with some genera (e.g. hieracium, the hawkweeds) having thousands of specific scientific names. The recent trend has been to recognize certain species as highly variable; but history dies hard, especially for those who discovered and described the "species". A flower is the reproductive unit of an angiosperm plant. There is an enormous variety of flowers, but all have some characteristics in common. The definitive characteristic of the angiosperms is the enclosed ovary, which contains and protects the developing seeds. Floral reproduction is bisexual, and flowers have "male" and "female" parts. The "male" or pollen-bearing part is called the stamen , and is composed of the filament and the anther . The "female" or seed-bearing part is called the pistil , and is composed of the ovary , the stigma , and the style . A flower may have exclusively male parts, exclusively female parts, or commonly, both.

When there are separate flower types, both may occur on the same plant; occasionally a plant may bear only male or female flowers. Surrounding the reproductive parts is the perianth , a double envelope consisting of an outer portion, the calyx , which forms the sepals , and an inner portion, the corolla , which forms the familiar petals . There may also be leafy elements, termed bracts , surrounding a flower. Individual flowers are often organized into a larger group or cluster, termed an inflorescence . The stalk supporting a single flower is called a pedicel , that supporting an inflorescence, or an isolated flower, a peduncle . Terms describing the inflorescence Inflorescence refers to the flowering body of a plant. These occur in an amazing variety of forms, from solitary flowers to enormously complex clusters, and there is an equally amazing variety of technical terminology used to describe them. Unfortunately, as with some other aspects of botany, this terminology is not universally standardized; different authors use different terms for the same structure, and sometimes the same terms in slightly or significantly different ways, and classify structures using different paradigms.

We only brush the surface here, making use of a few of the most commonly used terms. A basic and useful but somewhat non-immediately-obvious technical distinction is between determinate and indeterminate inflorescences. A determinate form has a fixed endpoint, usually a terminal flower that generally opens first. Lower side branches bear buds that open later. Indeterminate forms are often termed cymose or cymes. An indeterminate form is a shoot that can, at least theoretically, continue growing from the tip and producing more flowers indefinitely. The lower flowers open first, while upper buds may still be tiny and developing. Of course the whole process eventually comes to an end, but the distinction is frequently obvious. Indeterminate forms are termed racemose or racemes, though the latter term also has the more specific technical meaning described below. Of course in botany, nothing is ever simple. There are compound inflorescences that are mixtures of forms in every conceivable combination. The Parts of a Flower The Parts of a Flower A typical flower grows on a receptacle, or torus, an enlarged part of the flower stalk. The flower consists of four whorls, or sets, of parts.

The outermost whorl is the calyx. Within the calyx is the corolla. The calyx and corolla together form the perianth. The stamens, or male reproductive organs, lie within the corolla. The pistils, or female parts of the flower, make up the innermost whorl of parts. The Calyx is usually made up of small, green, leaflike sepals. These sepals protect the delicate inner parts of the flower bud. When the bud matures, the sepals usually spread apart widely, and may drop off. To prevent such insects as ants and beetles from climbing into the flower from below, the sepals may bend backward or bear special bristly structures. The Corolla usually consists of a group of colorful petals. The bright colors of the corolla attract insects and birds that pollinate the flower. Some flowers, such as the anemones, have no corolla. Their sepals have become petal-like in color and function. In many plants of the lily family, the sepals and petals are almost identical in size, shape, and color. Such sepals and petals together are called tepals.

Lizard's-tail flowers have neither calyx nor corolla, and botanists call them naked flowers. The petals of a flower may unite to form a structure resembling a tube, saucer, pouch, or other object. In the morning-glory , the corolla looks like a bell; in the moccasin flower, like a slipper; in the canary-bird vine, like a tiny flying canary; and in the sacred datura, like a long trumpet. The doubled flowers of our gardens, such as carnations and cabbage roses, may have hundreds of petals. The Stamens may vary in number from one to more than a thousand. They are usually separate from each other, but in some flowers they grow together to form a ring or cup and in others, such as lobelias, lupines, and mallows, they join to form a tube. In most plants, each stamen has a long, narrow filament, or stalk. Most filaments are like threads, but some are flat and look like paper. Others may have winged or toothlike edges. On top of the filament is an enlargement called the anther.

The anther usually consists of four baglike structures called pollen sacs or micro-sporangia. Dustlike pollen is produced in the sacs. Stamens are called staminodes if they lack anthers or if the anthers fail to produce pollen. The Pistils may vary in number from one to many. In some flowers, several separate pistils may join together to form a single compound pistil. Each pistil normally consists of three parts: the stigma, the style, and the ovary. The stigma, at the top, may be large and feathery or small and hard to see. When the stigma is "ripe," its sticky upper surface catches and holds any pollen grains that fall on it. Beneath the stigma, the long, slender style leads to a round or long chamber called the ovary. Sometimes the pistil has no style, and the stigma rests directly on top of the ovary. The ovules (egg cells) that develop into seeds, grow inside the ovary. World Book Encyclopedia.

Chicago: World Book-Childcraft International, Inc., 1979 Flower - flowers, fig, axis, whorl, floral, lateral and primary Flower Loading FLOWER, a term popularly used for the blossom of a plant, and so by analogy for the finest part or aspect of anything. Here it is dealt with only botanically. The flower is characteristic of the highest group of plants�the flowering plants (Phanerogams) �and is the association of more or less leaf-like organs which are concerned with the production of the seed. In modern botany the group is often known as the seed-plants or Spermophyta (see ANGIOSPERMS and GYMNOSPERMS). As the seed develops from the ovule, fertilised by the pollen, the essential structures for seed production are the pollen-bearer or stamen and the ovule-bearer or carpel. In comparative morphology, these are known as sporophylls because they bear the microspores (pollen-grains), developed in the microsporangia (pollen-sacs) or the megaspore, contained in the megasporangium (ovule).

In the more primitive gymnosperms (q.v.) the micro- or mega- sporophylls are gen erally associated in separate cones, to which the term "flower" has been applied. But it is to more definite and elaborate struc tures in the higher angiosperms (q.v.) that "flower" generally refers. Bracts. Flowers are produced from flower-buds in the axils of leaves called bracts; "bract" is properly restricted to the leaf from which the primary floral axis arises, while leaves which arise between the bract and the flower are bracteoles. Their arrange ment is similar to that of foliage leaves. In many cases, bracts protect the young flower, but they are sometimes undeveloped, and usually fall off early. Sometimes, especially with bracteoles, no flower-buds arise in their axils. At the base of the general umbel in umbelliferous plants is often a whorl of bracts, the general involucre, while partial involucres or involucels are found at the base of the umbellules. In Compositae the involucre sur rounds the heads of flowers (fig. 12).

When bracts become united, the outer ones often do not produce flowers. A sheathing bract or spathe, enclosing one or several flowers is common among monocotyledons and may, in some palms, reach 20 ft. in length and enclose 200,000 flowers. The spathe may be coloured (An thurium) or white (arum lily, Zantedeschia ethiopica). In grasses, the outer scales (glumes) of the spikelet are sterile bracts. Bracts may be changed into leaves (phyllody). Inflorescence. The arrangement of flowers on the axis is called the inflorescence. The primary axis of the inflorescence is the rachis; its branches, when present, are peduncles, which in turn may give rise to pedicels. A flower having a stalk is peduncu late or pedicellate; one with no stalk is sessile. To obviate any confusion, it is common to speak of the rachis as the primary floral axis, the peduncles as the secondary floral axes, and so on.

The peduncle may be simple, bearing a single flower, or branched. When it proceeds from radical leaves, it is a scape. The floral axis may be shortened, as in daisy and fig, or flattened, convex or concave in form and bearing numerous flowers, as in marigold or in fig. Adhesions occasionally take place between the peduncle and the bracts, as in the lime-tree (fig. I). The termination of the part upon which the whorls of the flower are arranged is the receptacle. There are two types of inflorescence�one in which the flowers arise as lateral shoots from a primary axis, which goes on elongat ing, and the lateral shoots never exceed in their development the length of the primary axis beyond their point of origin ; the flowers are thus axillary and the inflorescence is indeterminate. In the other type, the primary axis ends in a single flower, but lateral axes arise from the axils of bracts and repeat the process, the development of each lateral axis being stronger than that of the primary axis beyond its point of origin. The flowers are thus terminal and the inflorescence is definite.

In indeterminate in florescences, the lower or outer flowers expand first (centripetal) ; in determinate inflorescences, it is the upper or inner flowers that open first (centrifugal). In some inflorescences (mixed), the primary axis has an arrangement belonging to one type, the branches one of the opposite type. Amongst indefinite forms, the simplest is when a lateral shoot in the axil of a single foliage leaf ends in a single flower. In this case the flower is solitary. A more complicated inflorescence is commoner. Thus if the primary axis, as in fig. 2, is elongated and gives off pedicels ending in a single flower, a raceme is produced, which becomes a panicle if the secondary axes branch. If the lower flower-stalks are developed more strongly than the upper, and thus all the flowers are on a level, a corymb is formed, which may be simple (fig. 4) or branched. If the pedicels are wanting, so that the flowers are sessile, the result is a spike.

If this bears unisexual flowers it is a catkin; if it becomes succulent and sur rounded by a spathe it is a spadix, which may be simple (fig. 7) or branched. A spike with female flowers only and covered with scales, as in the hop, is a strobilus. In grasses there are usually numerous sessile flowers in small spikes (spikelets) ; if these are borne not on the primary but on secondary axes, they form a panicle. If the primary axis is contracted, other forms result. When it is so short that the secondary axes arise from a common point and spread out as radii of nearly equal length each ending in a single flower or dividing again similarly, an umbel (fig. 8) is produced. If there are numerous flowers on a flattened, convex or concave receptacle, having short pedicels or none, a capitulum is formed, as in marigold and scabious (fig. 3) . If the margins of the recep tacle are developed upwards, they may ultimately give rise to the hypanthodium of the fig.

In compound indefinite inflorescences, the lateral shoots, de veloped centripetally, bear numerous bracteoles from which floral shoots arise, which may have a centripetal arrangement similar to that on the mother shoot, or a different one. Thus we may have a group of racemes arranged in a racemose manner; compound umbels as in most Umbelliferae (fig. 8) ; a raceme of capitula ; a raceme of umbels, as in ivy, and so on. The simplest type of definite inflorescence is where, as in Anemone nemorosa, the axis terminates in a single flower, no other flowers being produced on the plant. This is a solitary terminal inflorescence. When the primary floral axis, before ending in a flower, gives off lateral unifloral axes which repeat the process, the result is a cyme. A cyme with two axes is a biparous cyme or dichasium (fig. II); with one axis, it is uniparous.

In the dead nettle (Lamium) the flowers arise in the axis of each foliage leaf and appear as if arranged in a whorl, but there is a central flower expanding first, and from its axis spring secondary axes bearing single flowers (fig. 1 o) . The inflorescence is thus a dichasium and the clusters are called verticillasters. Where numerous lateral axes arise from the primary axis, a cymose umbel is produced. When these lateral axes grow strongly and develop irregularly, as in species of muncus, the inflorescence is an anthela. In a uniparous cyme, the basal portion of the consecutive axes may become thickened and arranged more or less in a straight line, forming a false axis or sympodium, the inflorescence thus simulating a raceme. The uniparous cyme presents two forms ; in a scorpoid cyme the flowers are arranged alternately in a double row along one side of the sympodium, the bracts forming another double row on the opposite side (e.g., Boraginaceae).

In a helicoid cyme, the flowers are in a single row and form a spiral round the false axis. Compound definite inflorescences are by no means common, but in Streptocarpus polyanthus and in several calceolarias we probably have examples. Here we find scorpoid cymes of pairs of flowers, each pair consisting of an older and a younger flower. Both the definite and indefinite types are represented in mixed inflorescences. Thus in the ragwort (fig. 12) the heads of flowers are developed centrifugally, while the florets open centripetally. Various combinations occur in different families. Tabular View of Inflorescences \. indefinite Centripetal Inflorescences. I. Flowers solitary, axillary, Veronica hederifolia. II. Flowers in groups, pedicellate. i. Elongated form (Raceme), Hyacinth; (Corymb), Prunus. ii. Contracted form (Umbel), Cowslip. III. Flowers in groups, sessile.Iii. Flowers in groups, sessile. i.

Elongated form (Spike), Plantago. (Spikelet), grasses. Raceme of Scorpoid Cymes, Horse-chestnut. Scorpoid Cyme of Capitula, Vernonia scorpioides. Compound Umbel of dichotomous Cymes, Viburnum. Capitulum of contracted Scorpoid Cymes (Glomerulus), Sea pink. Cyme of Capitula, Ragwort. Parts of the Flower. The flower consists of the floral axis bearing the sporophylls (stamens and carpels) usually with pro tective envelopes. The axis is normally contracted, no internodes being developed and the portion bearing the floral leaves, the re ceptacle, is frequently a conical, flattened or hollowed expansion; rarely the axis is elongated and internodes are developed. Upon the receptacle the parts of the flower are crowded, usually form ing a series of whorls, the parts of which alternate, but sometimes arranged spirally, especially if the axis is elongated. In a typical flower (fig.

22) there are four distinct whorls, an outer calyx of sepals; within it, the parts alternating with those of the calyx, is the corolla of petals; next alternating with the parts of the corolla, the androeciunr of stamens; and in the centre, the gynoecium of carpels. Fig. 14 is a diagrammatic representation (floral diagram) of such a flower, supposed to be cut transversely, the parts of each whorl being distinguished by a different symbol. The sepals are usually greenish, their function is mainly protec tive, shielding the delicate internal organs before the flower opens. The petals are usually showy. Sometimes (usually in monoco tyledons) the calyx and corolla are similar; in such cases the term perianth is applied, and the parts of the calyx are petaloid. In some cases the petals resemble sepals (sepaloid). In plants, as Nympliaea alba (fig. 21), where a spiral arrangement of floral leaves occurs, these whorls pass insensibly into each other.

When both calyx and corolla are present, the plant is diclilamydeous; when one is absent, monochlamydeous (fig. 15). Sometimes both are absent (achlamydeous), as in willow. The stamens in their most differentiated form, consist each of a stalk, the filament (fig. i 6) consisting of pollen-sacs containing the powdery pollen (microspores) which is ultimately discharged. The gynoecium or pistil terminates the floral axis. It consists of one or more carpels (megaspores), separate or combined (fig. 17). The pistil is com posed of the ovary (fig. 20), the lower portion enclosing the ovules destined to become seeds; and the stigma loose cellular tissue, the receptive surface on which the pollen is deposited and either sessile on the apex of the ovary (poppy) or separated by a prolonged style. The androccium and gynoecium are not present in all flowers. When both are present the flower is hermaphrodite and is represented by the symbol .

When only one is present the flower is unisexual or diclinous, and is either male (staminate), or female (pistillate), ?. When all four whorls of leaves are present the flower is complete. Usually the successive whorls of the flower, disposed from below upwards or from without inwards upon the floral axis, are of the same number of parts, or are a multiple of the same number of parts, those of one whorl alter nating with those of the whorl next to it. In the more primitive types of flower the receptacle is more or less convex, and the series of organs follow in regular suc cession, culminating in the carpels (fig. i8). This arrangement is hypogynous, the other series being beneath (hypo) the gynoe cium. In other cases, the apex of the growing point ceases to develop and the parts below form a cup around it, from the rim of which the outer members of the flower are developed (perig ynous, fig. 19).

In many cases this is carried further and a cavity is formed roofed over by the carpels, so that the outer members of the flower spring from the edge of the receptacle which is immediately above the ovary (epigynous, fig. 2o). Symmetry of the Flower. When a flower consists of parts arranged in whorls it is cyclic, and if all the whorls have an -equal number of parts and are alternate it is eucyclic (figs. 14, In contrast to cyclic flowers are those where the parts are in spirals (acyclic). Flowers which are cyclic at one portion and spiral at another (as many Ranunculaceae) are hemicyclic. In spiral flowers there is usually a gradual passage from sepaloid through petaloid to staminal parts (water lily, fig. 21). In some cases the parts of one whorl are opposite or superposed to those of the next. The superposition of the stamens on the sepals in the Caryophyllaceae is due to the suppression of the petals.

A flower is symmetrical when each whorl consists of an equal number of parts, or when the parts of any one whorl are mul tiples of that preceding it. Thus, a symmetrical flower may have five sepals, five petals, five stamens and five carpels (fig. 14) or the number of any of these parts may be a multiple of five. In the staminal whorl especially it is common to find additional rows. In fig. 24 the parts are in fours; in figs. 25 and 26, in threes. The floral envelopes are rarely multiplied. Flowers in which the number of parts in each whorl is the same are isomerous; when the number in some whorls is different, the flower is anisomerous. It often happens that when fully formed, the number of parts in the pistillate whorl is not in conformity with that in the other whorls. In such circumstances a flower is called symmetrical, provided that the other whorls are normal (fig. 27).

A flower in which the parts are arranged in twos is dimerous; in threes, fours or fives, trimerous, tetramerous or pentamerous respectively. Trimerous symmetry is the rule in the monocotyledons, pentam erous the commonest in the dicotyledons, though dimerous and tetramerous flowers also occur in the latter group. The various parts of the flower have a definite relation to the central axis. Thus in a tetramerous flower, one sepal may be next the axis (superior or posterior), another next the bract (inferior or anterior) and the other two lateral (fig. 24). A plane passing through the anterior and posterior sepals and through the floral axis is the median plane of the flower; a plane cutting it at right angles and passing through the lateral sepals, is the lateral plane; whilst the planes which bisect the angles formed by the lateral and median planes are diagonal planes. In a pentamerous flower one sepal may be superior (Rosaceae and Labiatae) or inferior (pea family, figs.

28, 29) ; in the latter case the odd petal (vex illum) is then superior. In the Scrophulariaceae one of the two carpels is posterior, the other anterior, whilst in the Convol vulaceae the carpels are lateral. When the different members of each whorl are alike, the flower is regular; differences in size and shape of the parts of a whorl make the flower irregular (fig. 28). When a flower can be divided by a single plane into two similar parts it is zygomorphic (as in Papilionaceae). Polysymmetrical flowers have a radial sym metry and can be divided by several planes into similar por tions; such are all regular, symmetrical flowers. When the parts of any whorl are not equal to, or some multiple of, the others, the flower is asymmetrical. This alteration in the symmetrical arrangement has been traced to suppression or non-development of parts, degeneration or imperfect formation, cohesion or union of parts of the same whorl, adhesion or union of parts of different whorls, multiplication of parts and deduplication (chlorosis) or splitting of parts.

Cultivation has a great effect iri causing changes in the various parts of a plant. The changes in colour and form of flowers thus produced are endless. As a convenient method of expressing the arrangement of the parts of a flower, floral formulae have been derived. The follow ing is a simple mode : the whorls are represented by the letters S (sepals), P (petals), A (stamens), C (carpels) and a figure marked after each indicates the number of parts in that whorl. Thus S5P5A5C5 means that the flower is perfect, isomerous and pentamerous. The flower of Sedum (fig. 22) would be represented by S5P5A5+5C5, where A5+5 indicates that the staminal whorl consists of two rows of five parts each. Aestivation. The manner in which the parts are arranged in the flower-bud with respect to each other before opening is the aestivation or praefloration, and distinctive names have been given to the different arrangements exhibited, both by the leaves individually and in their relation to each other.

As regards each leaf of the flower, it is either spread out, as the sepals in the bud of the lime-tree, or folded upon itself (conduplicate), or slightly folded inwards or outwards at the edges, as in the calyx of some species of Clematis, or rolled up at the edges (involute or revolute), or folded transversely, becoming crumpled or cor rugated as in the poppy. When the parts of a whorl are in an exact circle, and are applied to each other by the edges only, without overlapping or folding, aestivation is valuate. The edges of each of the parts may be turned inwards (induplicate) or outwards (reduplicate). When the parts of a single whorl are placed in a circle, each of them exhibiting torsion so that by one of its sides it overlaps its neigh bour, whilst its side is overlapped in like manner by that standing next to it, aestivation is twisted or contorted. When the flower expands, traces of twisting sometimes remain. These forms of aestivation occur in cyclic flowers and are included under circular aestivation.

In spiral flowers the leaves may cover each other partially, like tiles on a house, or the parts may envelop each other completely (convolute). When the parts are five, as in many dicotyledons, there may be two parts external, two internal and a fifth which partially covers one of the inner parts by its margin and is in turn partially covered by one of the external parts (quincuncial), as in the corolla of Rosaceae. In the Leguminoseae, the vexillum is often large and folded over the others (vexillary) or the carina may perform a similar office (carinal). Circular aestivation is generally associated with a regular calyx and corolla while spiral aestivation is connected with irregular as well as regular forms. flowers, fig, axis, whorl, floral, lateral and primary From Encyclopedia Britannica Parts of the Flower Corolla | Garden Guides Parts of the Flower Corolla Parts of the Flower Corolla Reason for flagging? Submit The corolla is a term that means all the petals of the flower. However, in order to understand what the corolla is, you need to understand that what looks like a petal is not always a petal.

In fact, some flowers don't even have petals. This might seem confusing, but once you understand a little more about basic flower structure, it is easy to understand what parts of the flower make up the corolla. Petals Petals are soft, thin, typically brightly colored, modified leaves. Petals form whorls around the reproductive organs of a flower. The petals are usually the second whorl and have sepals surrounding them. However, not all plants have petals. Some, such as hellebores, have petaloid sepals, which means that the sepals are modified to look like petals. Corolla As said earlier, all the petals of the flower make up the corolla. In the picture of the rose, the corolla includes all of the pink petals, but does not include the green sepals (described below) nor does it include the reproductive parts of the flower such as the stamen and pistol. Sepals The sepals are part of the outer whorl of the flower. They are usually green, but not always. For example, day lilies have colored sepals. Like the corolla, they are non-fertile parts of the flower.

Although they are not part of the corolla, the corolla and the sepals of the flower are known as the perianth. Calyx The calyx includes all the sepals of the flower. It is the protective cover of the flower that once enclosed the bud. Tepals Tepals is a term traditionally used when flowers do not have distinguishable sepals and petals. A good example of this is the tulip, where both the inner and outer whorls appear the same. Perianth The perianth is the outer part of the flower and includes both the calyx and the corolla of the flower. Basically, the term is used to refer to all the non-fertile parts of the flower. This term is often used when the calyx (sepals) and corolla (petals) are hard to distinguish from each other. Who Can Help

Question: What is the name for the individual leaves of the calyx or outer whorl of a flower?
Answer: Sepal