Class 11 Biology NCERT Solutions

~5 min read

Morphology of Flowering Plants Class 11 Biology NCERT Solutions

The complete NCERT exercise solutions for Chapter 5, Morphology of Flowering Plants — 10 questions from Ex, each worked through step by step in the CBSE marking pattern. Root, stem and leaf modifications, inflorescence, flower, fruit and seed, placentation, and the description of a family.

Class:11Subject:BiologyChapter:5

3 Key Formulas

DWritten byDeep Narayan

UpdatedSeptember 2026

Key Concept Summary

How many questions are in NCERT Class 11 Biology Chapter 5?

Chapter 5 carries 1 exercise question, numbered Ex. All of them are solved step by step on this page, along with the chapter's key formulas and exam pointers.

Chapter Overview

This chapter is descriptive, and the ten questions below are the complete NCERT exercise set for Chapter 5, worked in the board pattern. Everything in it hangs off four ideas in order: the root, the stem, the leaf and the flower, and then the inflorescence. The examiner's habit in this chapter is to reward classification, so almost every answer here is a numbered list with a named category and an example attached to each, and a list written as running prose usually loses the example marks.

Write every list as category plus example

The single most common way to lose marks in this chapter is to name a category and forget its example. Phyllotaxy, placentation, aestivation, inflorescence and the types of compound leaves are all worth marks twice over, once for the classification and once for the example. So set them out as two columns of thought: the type, and the plant. A safe fallback when an example is forgotten is a genus rather than a common name, since Solanum, Brassica, Rosa and Citrus are always accepted where the vernacular name is not.

$Phyllotaxy : alternate (China rose, mango, guava), opposite (oleander, guava), whorled (Alstonia)$
$Placentation : basal, marginal, axile, free-central, parietal$
$Aestivation : valvate, twisted, imbricate, vexillary$

NCERT Chapter 5 Exercises (10 questions)

10Exercise questions

Step-by-step solution

1First agree on what the two have in common, because the difference is a difference of arrangement and not of structure. In both, the lamina is divided into leaflets, the leaflets are separated by gaps, and there is a single axillary bud at the base of the whole leaf, at the base of the petiole, and never at the base of an individual leaflet. This is the test that separates a compound leaf from a deeply lobed simple leaf, since in a lobed simple leaf there is an axillary bud at the base of each lobe.
2In a pinnately compound leaf the leaflets are borne on a common elongated axis, the rachis, which is a continuation of the petiole, and so the rachis represents the midrib. The leaflets are attached along its length on either side, in two rows, and a terminal leaflet may or may not be present. When a terminal leaflet is present the leaf is imparipinnate or odd-pinnate, as in neem and tamarind, and when it is absent the leaf is paripinnate or even-pinnate, as in the tamarind and in the honey locust. The examples are neem, Azadirachta indica, tamarind, Tamarindus indica, and rose, Rosa.
3In a palmately compound leaf the leaflets are attached at a single common point at the tip of the petiole, with no rachis between them, so the petiole itself ends in a point from which the leaflets radiate, rather like the fingers spread from the palm. The examples are the silk cotton tree, Bombax ceiba, and the lupin, Lupinus.
4So the difference to state is where the leaflets attach. On a pinnate leaf they attach along a definite central axis, the rachis, in two lateral rows, and the rachis may carry a terminal leaflet; on a palmate leaf they attach at one point at the tip of the petiole and radiate from it, with no rachis. The number of leaflets is also usually greater in the palmate type, since they must crowd into a single whorl, but the essential difference is the point of attachment, not the number.

Final answer

Both are compound leaves, in which the lamina is divided into leaflets separated by gaps, and in both a single axillary bud is present at the base of the whole leaf and never at the base of a leaflet, which is what distinguishes a compound leaf from a lobed simple leaf. They differ in where the leaflets are attached. In a pinnately compound leaf the leaflets are borne on a common elongated axis, the rachis, which is a continuation of the petiole and represents the midrib, and they are arranged along its length in two lateral rows; the rachis may carry a terminal leaflet, in which case the leaf is imparipinnate or odd-pinnate as in neem, or it may not, in which case it is paripinnate as in tamarind, and the examples are neem, Azadirachta indica, tamarind, Tamarindus indica, and rose. In a palmately compound leaf the leaflets are all attached at a single common point at the tip of the petiole, with no rachis between them, and they radiate from that point, so the petiole itself ends in the point of attachment; the examples are the silk cotton tree, Bombax ceiba, and the lupin, Lupinus. Thus the essential difference is the point of leaflet attachment, along a rachis in the pinnate condition and at a single point in the palmate condition.

Step-by-step solution

1Phyllotaxy is the arrangement of leaves at the nodes of the stem, and NCERT recognises three types, which are arranged here as the three marks are allotted.
2Alternate: at each node only a single leaf is borne, and the leaves are arranged in a spiral around the stem, so that each leaf is offset from the one above it. In the alternate distichous condition the leaves lie in two ranks along the stem, in one plane, but the common arrangement is the spiral one. The examples are the China rose, Hibiscus rosa-sinensis, the mango, Mangifera indica, and the guava, Psidium guajava.
3Opposite: at each node two leaves are borne, and they arise at the same level, at the same point but on opposite sides of the stem, so that the two are directly opposite one another. In the decussate condition the successive pairs are set at right angles to one another, so that pairs at one node are at right angles to the pairs at the node above and below, and the stem then shows four vertical rows of leaves. The examples are the oleander, Nerium odorum, and the guava, and the opposite decussate arrangement is the usual condition in the guava.
4Whorled: at each node more than two leaves are borne, that is three or more, and all the leaves arising at that node form a whorl around the stem. The examples are Alstonia scholaris, in which there may be six to eight leaves at a node, and the madar, Calotropis, in which five leaves form a whorl.
5So the classification rests on the number of leaves arising at a node: one, alternate; two, opposite; and three or more, whorled, and in each case the further subdivision depends on the angle at which the successive leaves or pairs are set.

Final answer

Phyllotaxy is the arrangement of the leaves at the nodes of the stem, and three types are recognised according to the number of leaves arising at each node. In the alternate type a single leaf arises at each node and the leaves are arranged in a spiral around the stem, so each leaf is offset from the one above it; in the alternate distichous condition the leaves lie in two ranks in a single plane. The examples are the China rose, Hibiscus rosa-sinensis, the mango, Mangifera indica, and the guava, Psidium guajava. In the opposite type two leaves arise at each node, at the same level and on opposite sides of the stem, and where successive pairs are set at right angles to one another the arrangement is called decussate, so that pairs at one node stand at right angles to the pairs at the node above and the node below, giving four vertical rows of leaves; the examples are the oleander, Nerium odorum, and the guava. In the whorled type three or more leaves arise at each node and form a whorl around the stem, as in Alstonia scholaris, where there may be six to eight leaves at a node, and in the madar, Calotropis, where five leaves form a whorl. Thus the classification depends simply on whether one, two, or three or more leaves arise at each node.

Step-by-step solution

1Seven short definitions, so give each in one precise sentence that names the organ or the plane concerned, and add one example or one identifying character to each.
2(a) Aestivation is the arrangement of the sepals and the petals in respect to one another in the floral bud. It is a character of the bud, not of the open flower, and the types are valvate, twisted, imbricate and vexillary.
3(b) Placentation is the arrangement of the ovules within the ovary, and the types are basal, marginal, axile, free-central and parietal.
4(c) Actinomorphic means radially symmetrical, that is a flower which can be divided into two equal halves by any plane passing through the centre, or through the axis, of the flower. The examples are the China rose, the mustard and the Datura.
5(d) Zygomorphic means bilaterally symmetrical, that is a flower which can be divided into two equal halves by only one plane passing through the centre, so only one vertical plane and not any plane will divide it into equal halves. The examples are the pea, the sweet pea, the lady's finger and the gulmohar.
6(e) A superior ovary is one in which the gynoecium occupies the centre and lies above the point of origin of the other floral parts, so that the sepals, petals, stamens and any other parts are all inserted below the ovary on the thalamus. The examples are the mustard, the China rose, the tomato and the lemon.
7(f) A perigynous flower is one in which the thalamus is cup-shaped or saucer-shaped, so that the gynoecium is surrounded by it, and the thalamus and all the other floral parts arise from the same point, the sepals, petals and stamens being borne on the rim of the cup while the ovary is enclosed within it. The examples are the rose and the pea, and in the rose the ovary is inferior, since it is enclosed within the cup, while in the pea the ovary is superior, since the calyx, corolla and stamens alone arise from the rim of the cup.
8(g) An epipetalous stamen is one whose filament is attached to the petal, so that the stamen appears to be carried on the corolla rather than arising independently from the thalamus; the condition of stamens being attached to the petals is what epipetalous means. The example is the water lily, and the contrasting condition, in which the stamens are attached to the sepals, is termed epiphyllous, as in the lily, the Calotropis and the Agave.

Final answer

(a) Aestivation is the arrangement of the sepals and petals in respect to one another in the floral bud, and it may be valvate, twisted, imbricate or vexillary. (b) Placentation is the arrangement of the ovules within the ovary, and it may be basal, marginal, axile, free-central or parietal. (c) Actinomorphic means radially symmetrical, so the flower can be divided into two equal halves by any plane passing through its centre or axis, as in the China rose, the mustard and the Datura. (d) Zygomorphic means bilaterally symmetrical, so the flower can be divided into two equal halves by only one plane, as in the pea, the sweet pea, the lady's finger and the gulmohar. (e) A superior ovary is one in which the gynoecium lies above the point of origin of the other floral parts, so the sepals, petals and stamens are all inserted below it on the thalamus, as in the mustard, the China rose, the tomato and the lemon. (f) A perigynous flower is one in which the thalamus is cup-shaped and surrounds the ovary, the thalamus and the other floral parts arising from the same point, with the sepals, petals and stamens borne on the rim of the cup and the ovary enclosed within it, as in the rose, where the ovary is enclosed within the cup and is therefore inferior, in contrast to the pea, where the ovary is superior. (g) An epipetalous stamen is one whose filament is attached to the petal, so that it is borne on the corolla, as in the water lily, the contrasting condition of attachment to the sepals being epiphyllous, as in the lily, Calotropis and Agave.

Step-by-step solution

1(a) The difference between the two inflorescence types turns on where the apex of the main axis ends, and that single fact explains almost everything else about them.
2In a racemose inflorescence the apical bud is never used up in producing flowers, so the growth of the main axis is unlimited and continues indefinitely, and the flowers are borne laterally in acropetal succession, that is in the order of opening from the base upwards towards the apex. The main axis is therefore the mother of the flowers, and the youngest flowers are at the apex. The examples are the raceme, the spike, the catkin or spadix, the corymb, the umbel, the racemose cyme and the panicle.
3In a cymose inflorescence the apical bud is used up in producing a flower, so the growth of the main axis is limited, that is determinate, and the further growth takes place only from the lateral buds. This produces a typical monochasial or dichasial or polychasial arrangement, and the flowers open in acropetal or centripetal order, that is from the apex downwards towards the base, so the oldest flowers are at the apex. The examples are the cyme, the dichasium, the polychasium, the scorpioid cyme and the helicoid cyme.
4The remaining contrasts to state are that the racemose inflorescence is generally centripetal in the sense of opening, is more commonly bisexual and is racemose with flowers on a defined axis, whereas the cymose is determinate, usually with the terminal flower first. Both may be compound, so racemose may become a panicle by branching and cymose a dichasium or polychasium.
5(b) The difference here is whether the carpels of the gynoecium are free or fused, and it is a character of the gynoecium alone.
6In an apocarpous gynoecium the carpels are free, that is not fused, and they may be many or one in number, and each carpel is a closed ovary with its own ovules, placenta and style and stigma. The examples are the family Ranunculaceae, with the rose, buttercup and Michelia, and the Michelia champaca is a standard single-carpel example.
7In a syncarpous gynoecium the carpels are fused, that is united, and two or more carpels are joined into a single structure, so there is one ovary with a common locule or with septa, a common style and a common stigma. The examples are the lemon and the orange, the mustard, the pea, the tomato, the hibiscus and the cotton. A syncarpous ovary may be unilocular, with false septa as in the mustard and the tomato, or multilocular, with true septa as in the lemon, the tomato and the hibiscus, and a further case is the free-central ovary of the Dianthus and the Primula, in which the carpels are fused at the centre but the septa are absent.

Final answer

(a) In a racemose inflorescence the apical bud is never used up in producing a flower, so the growth of the main axis is unlimited or indeterminate and continues, the main axis is called the mother of the flowers, the flowers are borne laterally, and they open in acropetal succession, that is from the base upwards towards the apex, so the youngest are at the apex. In a cymose inflorescence the apical bud is used up in producing a flower, so the growth of the main axis is limited or determinate and further growth occurs only from the lateral buds, giving a monochasial, dichasial or polychasial arrangement, and the flowers open in the reverse order, from the apex downwards towards the base, so the oldest are at the apex. The examples of the racemose type are the raceme, spike, catkin, spadix, corymb, umbel and panicle, and of the cymose type the cyme, dichasium, polychasium and the scorpioid and helicoid cymes. (b) In an apocarpous gynoecium the carpels are free and are not fused, so there may be many carpels or only one, and each carpel forms a closed ovary with its own ovules, placenta, style and stigma, as in Ranunculaceae, for instance the rose, the buttercup and Michelia. In a syncarpous gynoecium two or more carpels are fused into a single structure with a common ovary, style and stigma, as in the lemon, the mustard, the pea, the tomato, the hibiscus and the cotton, and such an ovary may be unilocular with false septa, as in the mustard and tomato, or multilocular with true septa, as in the lemon and hibiscus, or free-central as in Dianthus and Primula, in which the carpels are fused at the centre but the septa are absent.

Step-by-step solution

1This is a drawing question, so the marks are for the accuracy of the outline and the labels, and the answer must tell the examiner exactly which structures to put on the paper and in what order.
2(i) Gram seed, the seed of the gram, Cicer arietinum: draw a rough, angular, somewhat bean-shaped seed in a small diagram first, and then draw the longitudinal section enlarged. The gram seed is non-endospermic, and this single fact decides the whole drawing, because the cotyledons are large and completely fill the seed cavity, leaving no room for endosperm.
3In the longitudinal section of the gram seed label, from the outside in: the seed coat or testa, the outer coat, which is a single layer of thick, well developed cells and is the main protective covering and is also the part that turns red on cooking with copper sulphate in the seed viability test; the hilum, the scar where the funicle was attached; the micropyle, the small opening in the seed coat through which the radicle emerges during germination; and the chalaza, the region on the opposite side of the hilum where the funicle joins the seed. Then label the two large cotyledons, which are the bulk of the embryo, and note that they are the storage organ here, and between them at the plumular end label the plumule, or the embryonic shoot, and at the radicular end label the radicle, or the embryonic root, and the plumule and the radicle together with the short axis between them form the embryonic axis. Finally state in the caption that the gram seed is non-endospermic and dicotyledonous, and that the food is stored in the cotyledons.
4(ii) The vertical section of the maize seed, the grain of Zea mays: here the drawing is the opposite, because the maize grain is endospermic and monocotyledonous, so the single cotyledon is a thin shield-shaped structure, the scutellum, lying between the endosperm and the embryo, and it does not store the food.
5Draw the grain with the embryo at the base on one side, and in the longitudinal section label: the seed coat or pericarp, which in a caryopsis is fused with the fruit wall and is the outer covering, drawn as the squarish or rounded grain outline; the endosperm, which is large, starchy and the main storage tissue and fills most of the grain; the scutellum or cotyledon, the single thin shield-shaped cotyledon lying between the endosperm and the embryo, whose function is absorption and which is the plumule-bearing or the shield-shaped structure that absorbs the nutrients of the endosperm; the coleoptile, which is a protective covering over the plumule, the plumule being the developing shoot; the coleorhiza, which is a protective covering over the radicle, the radicle being the developing root; and the hilum and the micropyle, the micropyle being the opening at the base through which the root emerges. In the caption note that the maize grain is a one-seeded fruit, a caryopsis, so the pericarp and the seed coat are fused, that it is monocotyledonous, and that the food is stored in the endosperm.

Final answer

(i) Gram seed, of Cicer arietinum: draw a small rough angular seed and then its enlarged longitudinal section, and label the seed coat or testa, the single layer of thick protective cells, the hilum, the scar of the funicle, the micropyle, the small opening through which the radicle emerges, and the chalaza at the opposite end, the two large cotyledons which fill the entire seed cavity and serve as the storage organ, and the plumule or embryonic shoot and the radicle or embryonic root with the short embryonic axis between them. State in the caption that the gram seed is a non-endospermic dicotyledonous seed, so that the food is stored in the cotyledons. (ii) Vertical section of the maize grain, of Zea mays: label the pericarp or seed coat, which in this one-seeded fruit is fused with the fruit wall, the large starchy endosperm which fills the grain and is the storage tissue, the scutellum, the single thin shield-shaped cotyledon lying between the endosperm and the embryo and absorbing the endosperm's nutrients, the coleoptile protecting the plumule or developing shoot, the coleorhiza protecting the radicle or developing root, and the hilum and the micropyle at the base through which the root emerges. State in the caption that the maize grain is a caryopsis and therefore monocotyledonous, and that the food is stored in the endosperm rather than in the cotyledon.

Step-by-step solution

1A semi-technical description follows a fixed seven-part order, and the marks are awarded in that order, so the headings must all be present even when the plant named is the potato flower, Solanum tuberosum, or any other member.
2The order is: habit, calyx, corolla, androecium, gynoecium, and the inflorescence with the floral formula and the floral diagram. NCERT gives the description of the potato flower, and the potato, Solanum tuberosum, is the standard worked example, so it is safest to describe that and state that the family is Solanaceae, the potato family, and the genus is Solanum.
3Habit: an herbaceous, annual or perennial, branched herb, and in the potato the stem is underground, erect and the branch is aerial, herbaceous and angular. The leaves are alternate, simple and ovate, and they are quite gently lobed, and the flowers are bisexual and actinomorphic.
4Calyx: five and gamosepalous, that is the five sepals are united into a tube, which is called a gamosepalous calyx or calyx tube. The calyx is valvate in aestivation, and it is persistent. These three points, five gamosepalous, valvate and persistent, are the calyx characters to be written down.
5Corolla: five and gamopetalous, that is the five petals are united into a tube, which is called a gamopetalous corolla or corolla tube. The corolla is rotate in shape, valvate in aestivation, and plicate in bud, and it is hypogynous. The stamens are inserted into the corolla tube, so the corolla is epipetalous with the stamens, and this is the point that carries the family character.
6Androecium: five, epipetalous, and the stamens are five and are epipetalous, that is attached to the corolla, alternating with the petals, and the filaments are united forming a staminal tube or androecium tube, so the androecium is didynamous in the case of Salvia but in Solanum the five stamens are equal and alternate, alternating with the petals, and the anthers are tetrasporangiate and the filament is epipetalous, alternating with the corolla lobes. For the potato, five stamens, epipetalous, with the filaments united into a tube around the style, which is the androecium tube.
7Gynoecium: bicarpellary, syncarpous, ovary superior, and it is bicarpellary and syncarpous with a superior ovary, the two carpels being fused, the ovary bilocular with an axile placentation, the style terminal, the stigma capitate, and the ovary shown as bicarpellary, syncarpous with a superior ovary, axile placentation and a bilocular ovary. The number of carpels is two, and the placentation is axile with two locules.
8Now the floral formula and the diagram. The floral formula is the part that consolidates the description, and it should be written as: br, ?, %, K(5), C(5), A5, G(2) with a superior ovary, and axile placentation. The symbols to be shown are: bracteate, bisexual, actinomorphic, five fused sepals, five fused petals, five stamens on the petals, and two fused carpels with a superior ovary and axile placentation. NCERT writes the androecium of the potato as five epipetalous stamens, and the standard formula for the family is br, bisexual, actinomorphic, K(5), C(5), A5, G(2) superior, axile.
9The floral diagram: draw a circle for the thalamus or the mother axis, then four whorls in the order from outside in. The outermost whorl is the five united sepals, the calyx, drawn as five fused arcs, valvate. The second whorl is the five united petals, the corolla, valvate or plicate in bud and rotate. The third whorl is the five epipetalous stamens, drawn as five small anthers standing on the corolla and alternate with the corolla lobes, so the epipetalous condition is visible on the diagram. The innermost whorl is the gynoecium, drawn as two fused carpels forming a bilocular ovary in cross section, showing the axile placentation as two ovules on a central axis in each locule, with the style and stigma at the centre above. The diagram must show the ovary as superior, that is the other whorls drawn below its level.

Final answer

Solanaceae, the potato family, example Solanum tuberosum, the potato: the habit is herbaceous, the potato having an underground and an aerial angular herbaceous stem, with alternate, simple, ovate and lobed leaves, and the flowers bisexual and actinomorphic. The calyx is five, gamosepalous, with the sepals united into a tube, valvate in aestivation, and persistent. The corolla is five, gamopetalous, rotate, with the petals united, plicate in bud, and hypogynous. The androecium is five, epipetalous, so the stamens stand on the corolla, with the filaments united into a staminal tube around the style, and the anthers tetrasporangiate, alternating with the corolla lobes. The gynoecium is bicarpellary, syncarpous, with a superior ovary, bilocular, with axile placentation, a terminal style and a capitate stigma. The floral formula is br, bisexual, actinomorphic, K(5), C(5), A5, G(2) with the ovary superior and the placentation axile, and the inflorescence is a scorpioid cyme in the potato. The floral diagram, drawn from outside inwards, shows a circle for the thalamus, then five fused valvate sepals forming the calyx, then five fused valvate rotate petals forming the corolla, then five anthers borne on the corolla and alternating with the corolla lobes to show the epipetalous condition, and at the centre the two fused carpels in cross section as a bilocular ovary with a superior position, with two ovules on a central axis in each locule to show the axile placentation, the style and stigma above.

Step-by-step solution

1Five types, and the order to give them in is the order NCERT gives them, from the simplest to the most complex: basal, marginal, axile, free-central and parietal. For each, say where the placenta is and how many locules the ovary has, then give the example.
2Basal placentation: the placenta is at the base of the ovary, and it is single-chambered, that is unilocular, with usually a single ovule. The example is the sunflower, where the ovary is a one-chambered syncarpous gynoecium with a single basal ovule, and the placenta is at the base.
3Marginal placentation: the placenta is along the ventral margin or the inner margin of a single carpel, and the gynoecium is apocarpous, that is formed of a single free carpel, so it is unilocular, with usually two or more ovules on the marginal placenta. The example is the pea, and the legume, and the ovary of the pea has a single locule with the ovules borne on the ventral suture, which is the marginal placenta.
4Axile placentation: the placenta is on the central axis, and the ovary is syncarpous and multilocular, with the septa present, so the number of locules equals the number of carpels, and the ovules are borne on the central axis in each locule. The examples are the tomato, the lemon, the China rose, the hibiscus and the lemon, and the mustard is unilocular with false septa, so it is not axile.
5Free-central placentation: here also the placenta is on the central axis and the ovary is syncarpous, but the septa are absent, so the ovary is unilocular, and the central axis is free in the middle of the cavity and is not attached to the walls. This arises when the septa disappear during development, so the septa present in the young ovary are lost. The examples are the Dianthus and the Primula, and in some members such as the Nicandra the septa are present and the same flower is axile, so the condition is best described as derived from the axile by loss of the septa.
6Parietal placentation: the placenta is on the inner wall of the ovary, or on the periphery, and the ovary is syncarpous but unilocular, and it may be made multilocular by false septa, so that although the placenta is parietal the ovary appears divided into chambers. The examples are the mustard, where the unilocular ovary becomes falsely two-chambered after fertilisation because of the outgrowth of a false septum from the placenta, and the tomato, and the Argemone of the Papaveraceae, which has parietal placentation with false septa.

Final answer

Placentation is the arrangement of the ovules within the ovary, and five types are recognised, the order being from the simplest to the most complex. In basal placentation the placenta is at the base of the ovary, the ovary is unilocular and usually has a single ovule, as in the sunflower. In marginal placentation the placenta lies along the ventral or inner margin of a single carpel, so the gynoecium is apocarpous and unilocular with two or more ovules on that margin, as in the pea, where the ovules are borne on the ventral suture. In axile placentation the placenta is on the central axis, the ovary is syncarpous and multilocular with true septa, so that the number of locules equals the number of carpels, and ovules are borne on the central axis in each locule, as in the tomato, the lemon, the China rose and the hibiscus. In free-central placentation the placenta is also on the central axis and the ovary is syncarpous, but the septa are absent so the ovary is unilocular and the central axis is free and unattached to the walls, which is the condition in Dianthus and Primula, arising by the loss of the septa during development, as is clear in members such as Nicandra where the septa persist. In parietal placentation the placenta is on the inner wall or on the periphery of the ovary, which is syncarpous and unilocular but may appear multilocular where false septa divide it, as in the mustard, where the unilocular ovary becomes falsely bilocular after fertilisation because of an outgrowth from the placenta, and in the tomato and in Argemone, which has true parietal placentation with false septa.

Step-by-step solution

1Define the flower in one sentence, then describe the four whorls in the order they are given in the NCERT text, which is not the order students expect: calyx, corolla, androecium and finally gynoecium, because NCERT treats the gynoecium last and the whorl order in the diagram is calyx, corolla, androecium, gynoecium. Add a short note on the symmetry and the sex of the flower, and on placentation, at the end.
2Definition: a flower is the reproductive shoot of an angiosperm, and it is the structure that contains the stamens and the carpels, the organs that produce the male and the female gametes and so continue the species. It is regarded as a modified shoot, since it is a stem in which the leaves are modified, because sepals are modified leaves and petals, stamens and carpels are further modifications of the same leaf-like organ.
3The parts of a typical flower are four whorls. Each whorl is a set of organs at one level on the thalamus, or receptacle, which is the swollen end of the floral axis, and the four whorls are the calyx, the corolla, the androecium and the gynoecium. The calyx is the outermost whorl, the corolla the second, the androecium the third, and the gynoecium the innermost, so that the gynoecium occupies the centre.
4The calyx consists of the sepals, and it is the outermost whorl, and it is green in colour, since it is photosynthetic, and its function is protection, especially of the bud. If the sepals are free the condition is polysepalous and they form the calyx, and if the sepals are united the condition is gamosepalous and they form a gamosepalous calyx, or calyx tube, and the calyx may also show a cup-like shape and bear nectaries. The number is usually five.
5The corolla consists of the petals, the second whorl, and the petals are usually coloured and attractive, and they are the primary organs of attraction, using colour, scent and nectar guides to bring in pollinators, and so the corolla is a secondary floral character as against the calyx. If the petals are free the condition is polypetalous and they form the corolla, and if they are united the condition is gamopetalous and they form a gamopetalous corolla or corolla tube, and the union may be valvate, twisted, imbricate or vexillary in aestivation.
6The androecium consists of the stamens, the third whorl, and each stamen has a filament and an anther, the anther being usually four-lobed or two-lobed and the lobes being the pollen sacs, the microsporangia, where pollen is produced. The stamens may lie in the same plane, or one whorl within the other, or in the same plane, and the number and the arrangement is described by terms such as mono-, di-, tetra- and hexamerous, and the stamens may be free or united into one or more bundles, whether by the filaments or by the anthers, and the condition of being united is termed cohesion, while the fusion of stamens with the petals is termed adhesion.
7The gynoecium is the innermost whorl and it is the essential whorl, the only one that is always present, since it alone contains the ovules. It consists of one or more carpels, and it may be a single carpel, or several free carpels, which is apocarpous, or several fused carpels, which is syncarpous. Each carpel has a stigma, a style and an ovary, and the stigma receives the pollen, the style connects the stigma to the ovary and often assists in pollen germination and pollen tube growth, and the ovary encloses one or more ovules with their placenta, and the ovary is superior or inferior, the thalamus is hypogynous or perigynous, and the placentation may be any of the five types. The other three whorls are accessory organs, since they do not directly produce the gametes.
8Finally, the other characters to state: the flower may be unisexual, that is staminate or pistillate, or bisexual; it may be actinomorphic or zygomorphic; and the number of parts in each whorl is usually five in dicots, with parts in multiples of four or five, and four in monocots, with parts in multiples of three. The whole assemblage of the four whorls constitutes the flower, and the aestivation is the arrangement of sepals and petals in the bud.

Final answer

A flower is the reproductive shoot of an angiosperm, the structure that bears the stamens and the carpels which produce the male and female gametes, and it is a modified shoot in which the leaves are modified, since the sepals, petals, stamens and carpels are all leaf-like organs. It consists of four whorls borne on the thalamus or receptacle, the swollen end of the floral axis: the calyx, the corolla, the androecium and the gynoecium. The calyx is the outermost whorl and consists of the sepals, which are green and photosynthetic and whose function is to protect the bud; the sepals may be free, forming the calyx, or united, forming a gamosepalous calyx or calyx tube, and the number is usually five. The corolla is the second whorl and consists of the petals, which are coloured and attractive and whose main function is to attract pollinators by colour, scent and nectar guides, making the corolla a secondary floral character; the petals may be free, forming the corolla, or united, forming a gamopetalous corolla or corolla tube, and their union may be valvate, twisted, imbricate or vexillary, giving the polypetalous and gamopetalous conditions. The androecium is the third whorl and consists of the stamens, each with a filament and a usually four-lobed anther whose lobes are the microsporangia or pollen sacs; the stamens may be in one whorl, in two whorls, or in the same plane, and they may be free or united into one or more bundles, the union of the filaments being cohesion and the fusion with the petals adhesion. The gynoecium is the innermost whorl and the only essential whorl, since it alone bears the ovules; it consists of one or more carpels, which may be free, apocarpous, or fused, syncarpous, and each carpel has a stigma to receive the pollen, a style to connect the stigma to the ovary and often to assist pollen tube growth, and an ovary enclosing one or more ovules on a placenta, the ovary being superior or inferior and the thalamus hypogynous or perigynous. The other three whorls are accessory organs. A flower may additionally be unisexual, staminate or pistillate, or bisexual, and may be actinomorphic or zygomorphic.

Step-by-step solution

1Define the term, then give the basis of classification, and this is where the marks are: NCERT classifies inflorescences on two bases only, whether the axis is terminated by a flower, giving racemose or cymose, and whether the flowers are pedicellate or sessile, giving the two subdivisions. Nothing else counts as a basis.
2Definition: an inflorescence is the arrangement of flowers on a floral axis, and it is a peduncle, the axis bearing the flowers. The stalk of an individual flower is the pedicel, and a flower without a pedicel is sessile. This is the strict definition, and it is the term for the whole system of flowers borne on one axis, as distinct from the arrangement of flowers on the plant as a whole, which is a florescence or a flowering.
3Basis one, the mode of branching or the behaviour of the main axis, which gives the racemose and the cymose types. In a racemose or indefinite inflorescence the main axis does not terminate in a flower, so it continues to grow and the flowers are lateral, and the flowers open in the acropetal order, from the base towards the apex, so the youngest flowers are at the apex. The main axis is the mother of the flowers. In a cymose or definite inflorescence the main axis terminates in a flower, so its growth is limited, and the flowers open in the centripetal order, from the apex towards the base, so the oldest are at the apex, and the lateral axes also terminate in a flower, and there are three subtypes according to the number of lateral axes, the monochasium, dichasium and polychasium, and according to the arrangement of the branches, the scorpioid cyme and the helicoid cyme.
4Under the racemose head, the subdivision rests on whether the flowers are pedicellate or sessile. If the main axis is elongated and the flowers are pedicellate, it is a raceme, and if the flowers are sessile it is a spike; if the axis is short and the flowers are pedicellate, it is an umbel, and if the flowers are sessile it is a head or a capitulum; if the axis is flattened, the umbel is a compound umbel and the head is a disc; if the main axis and the successive laterals are all elongated, giving a branched raceme, it is a panicle; if the main axis is flat and the flowers are pedicellate, it is a corymb; and the spadix is a spike with a fleshy axis, and the catkin or the spike is a spike with pendulous flowers and a slender axis, as in the unisexual flowers of the mulberry and the oak.
5So the second basis is the presence or absence of a pedicel and the relative length and shape of the axis, which convert the raceme and the spike into the umbel, the head, the panicle, the corymb, the spadix and the catkin, while the first basis converts everything into the racemose or the cymose group.

Final answer

An inflorescence is the arrangement of flowers on a floral axis, and the axis bearing the flowers is called the peduncle, while the stalk of an individual flower is the pedicel, and a flower without a pedicel is sessile. Inflorescences are classified on two bases. The first is the mode of branching, that is the behaviour of the main axis, which divides them into racemose or indefinite and cymose or definite types. In a racemose inflorescence the main axis does not terminate in a flower, so its growth is unlimited, the axis is the mother of the flowers, the flowers are lateral, and they open in the acropetal order from the base towards the apex, so the youngest are at the apex. In a cymose inflorescence the main axis and the lateral axes terminate in flowers, so growth is limited, and the flowers open in the centripetal order from the apex towards the base, so the oldest are at the apex; the subtypes are the monochasium, dichasium and polychasium, according to the number of lateral axes, and the scorpioid and helicoid cymes, according to the arrangement of the branches. The second basis is whether the flowers are pedicellate or sessile, and this subdivides the racemose group: an elongated axis with pedicellate flowers gives a raceme, as in mustard, and with sessile flowers a spike, as in the gladiolus; a shortened axis with pedicellate flowers gives an umbel, as in the onion, and with sessile flowers a head or capitulum, as in the sunflower; a branched raceme gives a panicle, as in the branched raceme of the mango; a flattened axis with pedicellate flowers gives a corymb, as in the candytuft; a spike with a fleshy axis gives a spadix with a spathe, as in the Arum; and a spike with pendulous sessile flowers gives a catkin, as in the mulberry and the oak. Thus the two bases together account for all the types.

Step-by-step solution

1The question is asking about the aestivation, that is the arrangement of the floral members in the floral bud in relation to their insertion on the thalamus, and it is the same content as the aestivation part of Q3 but written out in full. NCERT treats it as a separate section, so give the treatment in full, together with the related point of the position of the ovary, since the NCERT text on this heading covers both the aestivation and the special condition of the perigynous flower.
2Begin with the general position of the whorls on the thalamus. The thalamus is the receptacle, the swollen end of the floral axis on which the floral parts are borne, and the four whorls, the calyx, the corolla, the androecium and the gynoecium, are arranged on it in a definite order from outside inwards. The whorls may be free, in which each whorl is separated from the others, or the members of a whorl may be united, and in any case the whorls are inserted on the thalamus in one of the three conditions of the ovary: hypogynous, perigynous and epigynous.
3Hypogynous: the thalamus is conical or disc-shaped and the gynoecium occupies the centre, lying above the point of origin of the other parts, so all the other whorls, the calyx, the corolla and the stamens, are borne below the ovary. The ovary is therefore said to be superior. The examples are the mustard, the China rose, the tomato, the lemon, the Datura and the mango, so the hypogynous flower is the commonest condition.
4Perigynous: the thalamus is cup-shaped or saucer-shaped, so the gynoecium is surrounded by it, and the thalamus and the other floral parts arise from the same point. The sepals, petals and stamens are borne on the rim of the cup, while the ovary sits within the cup enclosed by it, so the ovary is inferior. The example is the rose, and the pea is also perigynous but here the ovary is superior because the gynoecium is not enclosed within the cup, so in the pea only the calyx, corolla and stamens arise from the rim.
5Epigynous: the thalamus is flat and the other floral parts are borne above the gynoecium, and the ovary is enclosed within the tissue of the thalamus, so the ovary is inferior and the epigynous flower has a superior gynoecium in appearance because the other parts are above it. The examples are the Cucurbita, the guava, the carrot, the coriander and the sunflower, and in the epigynous flower the parts borne above the ovary are described as epigynous.
6Now the arrangement of the members of a whorl in the bud, which is the aestivation proper, and it is a character of the calyx and the corolla, and the four types are valvate, twisted, imbricate and vexillary. Valvate: the members of a whorl touch one another without any overlap, and they meet edge to edge, as in the calyx of the China rose and in the corolla of the tulip, or the calyx of the China rose and the corolla of the Datura. Twisted, or contorted: one member of the whorl overlaps the next in a regular and consistent direction, so one margin of each petal is inwards and the other margin outwards, as in the corolla of the china rose and of the lady's finger. Imbricate: the members of the whorl overlap one another irregularly without any fixed direction, as in the corolla of the pea and the china rose, and this is the commonest type. Vexillary or descending: one member of the whorl, the standard or the banner, is the largest and lies outside the two lateral wings, which in turn lie outside the two fused keel petals, giving a butterfly-like arrangement, and this is the corolla of the pea, of the papilionaceous corolla, and of the beans and the gram.
7So the complete answer to the question is: the floral members are inserted on the thalamus in the hypogynous, perigynous or epigynous position, which determines whether the ovary is superior or inferior, and within each whorl the members are arranged in the bud in the valvate, twisted, imbricate or vexillary manner, which is the aestivation.

Final answer

The floral members are inserted on the thalamus, or receptacle, which is the swollen end of the floral axis, in a definite arrangement, and there are two aspects of this arrangement. The first is the position of the whorls on the thalamus, which may be hypogynous, perigynous or epigynous. In the hypogynous flower the thalamus is conical or disc-shaped, the gynoecium occupies the centre and lies above the point of origin of the other parts, so the calyx, corolla and stamens are all borne below it and the ovary is superior, as in the mustard, the China rose, the tomato, the lemon and the Datura. In the perigynous flower the thalamus is cup- or saucer-shaped and surrounds the gynoecium, the thalamus and the other floral parts arising from the same point, the sepals, petals and stamens being borne on the rim of the cup and the ovary lying within it, so the ovary is inferior, as in the rose; in the pea the calyx, corolla and stamens also arise from the rim of the cup but the ovary is not enclosed, so the ovary is superior. In the epigynous flower the thalamus is flat and the other floral parts are borne above the gynoecium, the ovary being enclosed within the tissue of the thalamus and therefore inferior, as in the Cucurbita, the guava, the carrot and the coriander. The second aspect is the arrangement of the members of a whorl in the bud, which is the aestivation, and it has four types: valvate, where the members touch without overlapping, as in the calyx of the China rose and the corolla of the tulip; twisted or contorted, where one member regularly overlaps the next in one direction, as in the corolla of the China rose and the lady's finger; imbricate, where the members overlap irregularly without a fixed direction, as in the corolla of the pea; and vexillary or descending, where one large standard petal lies outside two lateral wings, which in turn lie outside two fused keel petals, giving the butterfly-shaped corolla of the pea, the beans and the gram.

Quick Revision

Key formulas at a glance

Memorise these equations — direct application numericals and derivations in CBSE & JEE frequently hinge on these.

Placentation

marginal, axile, parietal, free-central, basal

Androecium terms

monothecous, dithecous; staminate vs pistillate

Floral formula

% symmetry calyx corolla androecium gynoecium

Exam Strategy

How this chapter is asked

High-yield question patterns observed across CBSE boards, JEE Main & Advanced, and NEET.

Indeterminate and determinate inflorescence are decided by whether the apex is used up, not by how the flowers are arranged.
Superior and inferior ovaries are distinguished by the position of the ovary relative to the other floral whorls, which is what makes fruit a superior or inferior one.
A family description needs a floral formula, a labelled diagram and the identifying features in a fixed order; Solanaceae and Liliaceae are the two asked.

FAQ

Frequently asked questions

How many questions are in NCERT Class 11 Biology Chapter 5 (Morphology of Flowering Plants)?

There are 1 exercise question in this chapter, numbered Ex. Every one is solved step by step on this page in the official NCERT numbering.

Which formulas come up in Morphology of Flowering Plants Class 11 Biology?

The formulas this chapter's questions actually turn on are: Placentation, Androecium terms, Floral formula. They are listed with their expressions in the key formulas section below, and the solved questions show where each one is used.

Is Morphology of Flowering Plants important for NEET?

Important and heavily diagram-based — the Solanaceae description carries a full-marks question in both boards and NEET, and placentation is asked in short form very often.

Next Chapters

Continue learning

Next: Anatomy of Flowering Plants Morphology of Flowering Plants revision notes

Same solutions, live doubt-clearing help

Reading a solution is step one — getting a doubt resolved in real time is what clears it. ClassApna runs small-batch CBSE, JEE & NEET coaching with daily doubt sessions and mock tests.

Book a Free Demo Class Explore Plans & Batches

Small batches · 1-on-1 personal mentorship · Live online & offline centre