1. Chapter at a Glance
Flowering plants show enormous variation in shape, size, structure, mode of nutrition, life span, habit and habitat. Despite this, they share a common body plan: a root system below the ground and a shoot system (stem, leaves, flowers and fruits) above it. Morphology is the study of the external form of these organs. This chapter describes roots, stems and leaves with their modifications, the arrangement of flowers (inflorescence), the parts of a flower, fruits and seeds, the semi-technical description of a plant, and three important families — Fabaceae, Solanaceae and Liliaceae. NEET asks two to three questions every year, mostly on aestivation, placentation, position of the ovary, modifications and floral formulae.
- Root, stem and leaf modifications with standard examples.
- Phyllotaxy, venation, simple vs compound leaves.
- Racemose vs cymose inflorescence.
- Hypogynous, perigynous and epigynous flowers; aestivation types; placentation types.
- Epipetalous and epiphyllous stamens; mono-, di- and polyadelphous stamens.
- Floral formulae and economic importance of Fabaceae, Solanaceae and Liliaceae.
2. The Root
In the majority of dicotyledonous plants, the direct elongation of the radicle leads to the formation of the primary root, which grows inside the soil. It bears lateral roots of several orders, referred to as secondary, tertiary and so on. The primary root and its branches constitute the tap root system, as seen in the mustard plant. In monocotyledonous plants, the primary root is short-lived and is replaced by a large number of roots. These roots originate from the base of the stem and constitute the fibrous root system, as seen in the wheat plant. In some plants, like grass, Monstera and the banyan tree, roots arise from parts of the plant other than the radicle and are called adventitious roots.
The main functions of the root system are absorption of water and minerals from the soil, providing proper anchorage to the plant parts, storing reserve food material and synthesis of plant growth regulators.
Regions of the root
- The root is covered at the apex by a thimble-like structure called the root cap. It protects the tender apex of the root as it makes its way through the soil.
- A few millimetres above the root cap is the region of meristematic activity. The cells of this region are very small, thin-walled and with dense protoplasm. They divide repeatedly.
- The cells proximal to this region undergo rapid elongation and enlargement and are responsible for the growth of the root in length. This is the region of elongation.
- The cells of the elongation zone gradually differentiate and mature. Hence, this zone, proximal to the region of elongation, is called the region of maturation. From this region some of the epidermal cells form very fine and delicate, thread-like structures called root hairs. These root hairs absorb water and minerals from the soil.
Modifications of root
| Modification | Function | Examples | NEET Note |
|---|---|---|---|
| Storage (tap root) | Store food | Carrot, turnip | Swollen tap roots |
| Storage (adventitious) | Store food | Sweet potato | Sweet potato is a root, potato is a stem |
| Prop roots | Support | Banyan tree | Hanging roots from branches |
| Stilt roots | Support | Maize, sugarcane | Arise from lower nodes of the stem |
| Pneumatophores | Respiration (getting oxygen) | Rhizophora (swampy areas) | Many roots come out of the ground and grow vertically upwards |
3. The Stem
The stem is the ascending part of the axis bearing branches, leaves, flowers and fruits. It develops from the plumule of the embryo of a germinating seed. The stem bears nodes and internodes. The region of the stem where leaves are born are called nodes, while internodes are the portions between two nodes. The stem bears buds, which may be terminal or axillary. The stem is generally green when young and later often becomes woody and dark brown. The main function of the stem is spreading out branches bearing leaves, flowers and fruits. It conducts water, minerals and photosynthates. Some stems perform the function of storage of food, support, protection and vegetative propagation.
Modifications of stem
| Modification | Function | Examples | NEET Note |
|---|---|---|---|
| Underground storage stems | Store food; perennation during unfavourable conditions | Potato (tuber), ginger, turmeric (rhizome), zaminkand / Amorphophallus (corm), Colocasia (corm) | Identified as stems because they bear nodes, internodes and buds ("eyes" of potato) |
| Stem tendrils | Climbing | Gourds (cucumber, pumpkin, watermelon), grapevines | Develop from axillary buds; slender and spirally coiled |
| Thorns | Protection from browsing animals | Citrus, Bougainvillea | Axillary buds of stems modified into woody, straight and pointed thorns |
| Phylloclade (flattened stem) | Photosynthesis in arid regions | Opuntia | Flattened stem; leaves modified into spines |
| Fleshy cylindrical stem | Photosynthesis, water storage | Euphorbia | Contains chlorophyll |
| Runner (sub-aerial) | Vegetative propagation | Grass, strawberry | Stem spreads to new niches; old parts die and new plants form |
| Stolon | Vegetative propagation | Mint, jasmine | Slender lateral branch from base of main axis; arches downwards to touch the ground |
| Offset | Vegetative propagation | Pistia, Eichhornia (aquatic) | A lateral branch with short internode; each node bears a rosette of leaves and a tuft of roots |
| Sucker | Vegetative propagation | Banana, pineapple, Chrysanthemum | Lateral branches originate from the basal and underground portion of the main stem, grow horizontally beneath the soil and then come out obliquely upwards |
A modified organ is a stem if it has nodes, internodes, buds or scale leaves. That is why potato, ginger, turmeric, Colocasia and onion are stems, while carrot, turnip and sweet potato are roots. Tendrils of pea are leaflets (leaf modification), but tendrils of cucumber and grapevine are stems.
4. The Leaf
The leaf is a lateral, generally flattened structure borne on the stem. It develops at the node and bears a bud in its axil. The axillary bud later develops into a branch. Leaves originate from shoot apical meristems and are arranged in an acropetal order. They are the most important vegetative organs for photosynthesis.
A typical leaf consists of three main parts: leaf base, petiole and lamina. The leaf is attached to the stem by the leaf base and may bear two lateral small leaf-like structures called stipules. In monocotyledons, the leaf base expands into a sheath covering the stem partially or wholly. In some leguminous plants, the leaf base may become swollen, which is called the pulvinus. The petiole helps hold the blade to light. Long, thin, flexible petioles allow leaf blades to flutter in wind, thereby cooling the leaf and bringing fresh air to the leaf surface. The lamina or leaf blade is the green expanded part of the leaf with veins and veinlets. There is, usually, a middle prominent vein, which is known as the midrib. Veins provide rigidity to the leaf blade and act as channels of transport for water, minerals and food materials.
Venation
The arrangement of veins and veinlets in the lamina of a leaf is termed venation. When the veinlets form a network, the venation is termed reticulate. When the veins run parallel to each other within a lamina, the venation is termed parallel. Leaves of dicotyledonous plants generally possess reticulate venation, while parallel venation is the characteristic of most monocotyledons.
Types of leaves
- A leaf is said to be simple when its lamina is entire or, when incised, the incisions do not touch the midrib.
- When the incisions of the lamina reach up to the midrib, breaking it into a number of leaflets, the leaf is called compound. A bud is present in the axil of the petiole in both simple and compound leaves, but not in the axil of leaflets of the compound leaf.
- In a pinnately compound leaf, a number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf, as in neem.
- In palmately compound leaves, the leaflets are attached at a common point, i.e. at the tip of the petiole, as in silk cotton.
Phyllotaxy
Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. This is usually of three types:
- Alternate: a single leaf arises at each node in alternate manner, as in china rose, mustard and sunflower plants.
- Opposite: a pair of leaves arise at each node and lie opposite to each other, as in Calotropis and guava plants.
- Whorled: if more than two leaves arise at a node and form a whorl, as in Alstonia.
Modifications of leaves
| Modification | Function | Examples | NEET Note |
|---|---|---|---|
| Tendrils | Climbing | Peas | Leaflets modified |
| Spines | Defence | Cacti | Reduce water loss |
| Fleshy leaves | Store food | Onion, garlic | Fleshy scale leaves of the bulb |
| Phyllode | Photosynthesis | Australian acacia | Leaves small and short-lived; petioles expand, become green and synthesise food |
| Pitcher / bladder | Trapping insects | Pitcher plant, Venus fly trap | Insectivorous plants |
5. The Inflorescence
A flower is a modified shoot wherein the shoot apical meristem changes to floral meristem. Internodes do not elongate and the axis gets condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves. When a shoot tip transforms into a flower, it is always solitary. The arrangement of flowers on the floral axis is termed inflorescence. Depending on whether the apex gets converted into a flower or continues to grow, two major types of inflorescences are defined:
- Racemose: the main axis continues to grow; the flowers are borne laterally in an acropetal succession (older flowers at the base, younger towards the apex).
- Cymose: the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order (older flower at the top).
6. The Flower
The flower is the reproductive unit in the angiosperms. It is meant for sexual reproduction. A typical flower has four different kinds of whorls arranged successively on the swollen end of the stalk or pedicel, called the thalamus or receptacle. These are calyx, corolla, androecium and gynoecium. Calyx and corolla are accessory organs, while androecium and gynoecium are reproductive organs. In some flowers like lily, the calyx and corolla are not distinct and are termed perianth. When a flower has both androecium and gynoecium, it is bisexual. A flower having either only stamens or only carpels is unisexual.
Symmetry
- Actinomorphic (radial symmetry): the flower can be divided into two equal radial halves in any radial plane passing through the centre, e.g. mustard, datura, chilli.
- Zygomorphic (bilateral symmetry): the flower can be divided into two similar halves only in one particular vertical plane, e.g. pea, gulmohur, bean, Cassia.
- Asymmetric (irregular): it cannot be divided into two similar halves by any vertical plane passing through the centre, as in canna.
A flower may be trimerous, tetramerous or pentamerous when the floral appendages are in multiples of 3, 4 or 5, respectively. Flowers with bracts — reduced leaves found at the base of the pedicel — are called bracteate, and those without bracts, ebracteate.
Position of floral parts on the thalamus
| Type | Position of ovary | Arrangement | Examples | NEET Note |
|---|---|---|---|---|
| Hypogynous | Superior | Gynoecium occupies the highest position; other parts are situated below it | Mustard, china rose, brinjal | Most common in families studied |
| Perigynous | Half-inferior | Gynoecium in the centre; other parts on the rim of the thalamus at almost the same level | Plum, rose, peach | Thalamus cup-shaped |
| Epigynous | Inferior | Margin of thalamus grows upward enclosing the ovary completely and fusing with it; other parts arise above the ovary | Guava, cucumber, ray florets of sunflower | Ovary fused with thalamus |
Parts of a flower
- Calyx is the outermost whorl of the flower and its members are called sepals. Generally, sepals are green, leaf-like and protect the flower in the bud stage. The calyx may be gamosepalous (sepals united) or polysepalous (sepals free).
- Corolla is composed of petals. Petals are usually brightly coloured to attract insects for pollination. Like calyx, corolla may also be gamopetalous (petals united) or polypetalous (petals free). The shape and colour of corolla vary greatly in plants: tubular, bell-shaped, funnel-shaped or wheel-shaped.
Aestivation
The mode of arrangement of sepals or petals in a floral bud with respect to the other members of the same whorl is known as aestivation.
| Type | Arrangement | Examples | NEET Note |
|---|---|---|---|
| Valvate | Sepals or petals in a whorl just touch one another at the margin, without overlapping | Calotropis | No overlap |
| Twisted | One margin of the appendage overlaps that of the next one, and so on | China rose, lady's finger, cotton | Regular overlap in one direction |
| Imbricate | Margins of sepals or petals overlap one another but not in any particular direction | Cassia, gulmohur | Irregular overlap |
| Vexillary (papilionaceous) | Five petals: the largest (standard) overlaps the two lateral petals (wings), which in turn overlap the two smallest anterior petals (keel) | Pea, bean | Characteristic of Fabaceae |
Androecium
- Androecium is composed of stamens. Each stamen, which represents the male reproductive organ, consists of a stalk or a filament and an anther. Each anther is usually bilobed and each lobe has two chambers, the pollen-sacs. The pollen grains are produced in pollen-sacs. A sterile stamen is called a staminode.
- Stamens of a flower may be united with other members such as petals or among themselves. When stamens are attached to the petals, they are epipetalous, as in brinjal, or epiphyllous when attached to the perianth, as in the flowers of lily.
- The stamens in a flower may either remain free (polyandrous) or may be united in varying degrees. The stamens may be united into one bunch or one bundle (monoadelphous) as in china rose, or two bundles (diadelphous) as in pea, or into more than two bundles (polyadelphous) as in citrus. There may be a variation in the length of filaments within a flower, as in Salvia and mustard.
Gynoecium
- Gynoecium is the female reproductive part of the flower and is made up of one or more carpels. A carpel consists of three parts, namely stigma, style and ovary. The ovary is the enlarged basal part, on which lies the elongated tube, the style. The style connects the ovary to the stigma. The stigma is usually at the tip of the style and is the receptive surface for pollen grains. Each ovary bears one or more ovules attached to a flattened, cushion-like placenta.
- When more than one carpel is present, they may be free (as in lotus and rose) and are called apocarpous. They are termed syncarpous when carpels are fused, as in mustard and tomato. After fertilisation, the ovules develop into seeds and the ovary matures into a fruit.
Placentation
The arrangement of ovules within the ovary is known as placentation.
| Type | Arrangement | Examples | NEET Note |
|---|---|---|---|
| Marginal | Placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge, forming two rows | Pea | Monocarpellary ovary |
| Axile | Placenta is axial and the ovules are attached to it in a multilocular ovary | China rose, tomato, lemon | Ovary with several chambers |
| Parietal | Ovules develop on the inner wall of the ovary or on the peripheral part; ovary is one-chambered but becomes two-chambered due to the formation of the false septum | Mustard, Argemone | False septum (replum) in mustard |
| Free central | Ovules are borne on the central axis and septa are absent | Dianthus, Primrose | No septa |
| Basal | Placenta develops at the base of the ovary and a single ovule is attached to it | Sunflower, marigold | Single ovule |
NEET often gives four pairs and asks which is mismatched. Lock these: marginal – pea; axile – china rose, tomato, lemon; parietal – mustard, Argemone; free central – Dianthus, primrose; basal – sunflower, marigold. Aestivation: valvate – Calotropis; twisted – china rose, cotton, lady's finger; imbricate – Cassia, gulmohur; vexillary – pea, bean.
7. The Fruit and the Seed
The fruit is a characteristic feature of the flowering plants. It is a mature or ripened ovary, developed after fertilisation. If a fruit is formed without fertilisation of the ovary, it is called a parthenocarpic fruit. Generally, the fruit consists of a wall or pericarp and seeds. The pericarp may be dry or fleshy. When the pericarp is thick and fleshy, it is differentiated into the outer epicarp, the middle mesocarp and the inner endocarp. In mango and coconut, the fruit is known as a drupe. They develop from a monocarpellary superior ovary and are one-seeded. In mango the pericarp is well differentiated into an outer thin epicarp, a middle fleshy edible mesocarp and an inner stony hard endocarp. In coconut, which is also a drupe, the mesocarp is fibrous.
The ovules after fertilisation develop into seeds. A seed is made up of a seed coat and an embryo. The embryo is made up of a radicle, an embryonal axis and one (as in wheat, maize) or two cotyledons (as in gram and pea).
Dicotyledonous seed (e.g. bean, gram, pea)
- The outermost covering of a seed is the seed coat. The seed coat has two layers, the outer testa and the inner tegmen.
- The hilum is a scar on the seed coat through which the developing seed was attached to the fruit. Above the hilum is a small pore called the micropyle.
- Within the seed coat is the embryo, consisting of an embryonal axis and two cotyledons. The cotyledons are often fleshy and full of reserve food materials. At the two ends of the embryonal axis are present the radicle and the plumule.
- In some seeds such as castor, the endosperm formed as a result of double fertilisation is a food storing tissue (endospermic seeds). In plants such as bean, gram and pea, the endosperm is not present in mature seeds, and such seeds are called non-endospermous.
Monocotyledonous seed (e.g. maize)
- Generally, monocotyledonous seeds are endospermic, but some, as in orchids, are non-endospermic.
- In the seeds of cereals such as maize, the seed coat is membranous and generally fused with the fruit wall. The endosperm is bulky and stores food.
- The outer covering of the endosperm separates the embryo by a proteinous layer called the aleurone layer.
- The embryo is small and situated in a groove at one end of the endosperm. It consists of one large and shield-shaped cotyledon known as the scutellum and a short axis with a plumule and a radicle. The plumule and radicle are enclosed in sheaths, which are called coleoptile and coleorhiza, respectively.
| Feature | Dicot seed (pea, gram) | Monocot seed (maize) | NEET Note |
|---|---|---|---|
| Cotyledons | Two, fleshy | One, shield-shaped (scutellum) | — |
| Endosperm | Usually absent (castor is endospermic) | Bulky (orchid is non-endospermic) | Exceptions are frequently asked |
| Aleurone layer | Absent | Present (proteinous) | — |
| Sheaths | Absent | Coleoptile (plumule), coleorhiza (radicle) | — |
8. Semi-technical Description of a Flowering Plant
Various morphological features are used to describe a flowering plant. The description has to be brief, in a simple and scientific language and presented in a proper sequence. The plant is described beginning with its habit, vegetative characters — roots, stem and leaves — and then floral characters: inflorescence and flower parts. After describing the various parts of the plant, a floral diagram and a floral formula are presented.
The floral formula is represented by some symbols: Br for bracteate, K for calyx, C for corolla, P for perianth, A for androecium and G for gynoecium. G (line below G) indicates a superior ovary and G (line above G) an inferior ovary. ♂ stands for male, ♀ for female and ⚥ for bisexual flowers; ⊕ for actinomorphic and % for zygomorphic nature of the flower. Fusion is indicated by enclosing the figure within brackets, and adhesion by a line drawn above the symbols of the floral parts.
A floral diagram provides information about the number of parts of a flower, their arrangement and the relation they have with one another. The position of the mother axis with respect to the flower is represented by a dot on the top of the floral diagram. Calyx, corolla, androecium and gynoecium are drawn in successive whorls, calyx being the outermost and the gynoecium being in the centre.
9. Description of Some Important Families
| Feature | Fabaceae | Solanaceae | Liliaceae | NEET Note |
|---|---|---|---|---|
| Earlier name / common name | Papilionoideae (subfamily of Leguminosae); pea family | Potato family | Lily family; typical monocot | — |
| Habit / root | Trees, shrubs, herbs; tap root with root nodules | Mostly herbs, shrubs, rarely small trees | Perennial herbs with underground bulbs / corms / rhizomes | Root nodules fix N₂ |
| Stem | Erect or climber | Herbaceous, rarely woody, aerial, erect, cylindrical, branched, solid or hollow, hairy or glabrous; underground stem in potato (Solanum tuberosum) | — | — |
| Leaves | Alternate, pinnately compound or simple; leaf base pulvinate; stipulate; venation reticulate | Alternate, simple, rarely pinnately compound, exstipulate; venation reticulate | Mostly basal, alternate, linear, exstipulate with parallel venation | — |
| Inflorescence | Racemose | Solitary, axillary or cymose as in Solanum | Solitary / cymose; often umbellate clusters | — |
| Flower | Bisexual, zygomorphic | Bisexual, actinomorphic | Bisexual, actinomorphic | — |
| Calyx / perianth | Sepals five, gamosepalous; imbricate aestivation | Sepals five, united, persistent, valvate aestivation | Tepals six (3+3), often united into a tube; valvate aestivation | Persistent calyx in Solanaceae |
| Corolla | Petals five, polypetalous, papilionaceous: one posterior standard, two lateral wings, two anterior ones forming a keel (enclosing stamens and pistil); vexillary aestivation | Petals five, united; valvate aestivation | — | — |
| Androecium | Ten, diadelphous (9 + 1); anther dithecous | Stamens five, epipetalous | Stamens six, 3+3, epiphyllous | Diadelphous vs epipetalous vs epiphyllous |
| Gynoecium | Ovary superior, mono-carpellary, unilocular with many ovules; style single | Bicarpellary, syncarpous; ovary superior, bilocular; placenta swollen with many ovules; carpels obliquely placed | Tricarpellary, syncarpous; ovary superior, trilocular with many ovules; axile placentation | — |
| Fruit / seed | Legume; seed one to many, non-endospermic | Berry or capsule; seeds many, endospermous | Capsule, rarely berry; seed endospermous | — |
| Floral formula | % ⚥ K(5) C1+2+(2) A(9)+1 G1 | ⊕ ⚥ K(5) C(5) A5 G(2) (stamens epipetalous) | ⊕ ⚥ P(3+3) A3+3 G(3) (stamens epiphyllous) | Most asked |
| Economic importance | Pulses (gram, arhar, sem, moong, soyabean); edible oil (soyabean, groundnut); dye (indigofera); fibres (sunhemp); fodder (Sesbania, Trifolium); ornamentals (lupin, sweet pea); medicine (muliathi) | Food (tomato, brinjal, potato); spice (chilli); medicine (belladonna, ashwagandha); fumigatory (tobacco); ornamentals (petunia) | Ornamentals (tulip, Gloriosa); medicine (Aloe); vegetables (Asparagus); colchicine (Colchicum autumnale) | Colchicine from Liliaceae induces polyploidy |
10. Master Summary Table
| Topic | Key point | NEET Note |
|---|---|---|
| Root systems | Tap (dicot), fibrous (monocot), adventitious | Banyan prop roots, maize stilt roots, Rhizophora pneumatophores |
| Stem modifications | Storage, tendril, thorn, phylloclade, runner, stolon, offset, sucker | Nodes and buds identify stems |
| Leaf | Simple / compound; reticulate / parallel; phyllotaxy | Neem pinnate, silk cotton palmate |
| Inflorescence | Racemose (acropetal) vs cymose (basipetal) | — |
| Ovary position | Hypo-, peri-, epigynous | Guava, cucumber = inferior |
| Aestivation | Valvate, twisted, imbricate, vexillary | Pea = vexillary |
| Placentation | Marginal, axile, parietal, free central, basal | Mustard = parietal |
| Fruit | Ripened ovary; drupe (mango, coconut) | Mango mesocarp edible; coconut mesocarp fibrous |
| Seed | Dicot (non-endospermic) vs monocot (endospermic) | Castor endospermic; orchid non-endospermic |
| Families | Fabaceae, Solanaceae, Liliaceae | Diadelphous, epipetalous, epiphyllous |
11. Mind Map
- Root and modifications
- Stem and modifications
- Leaf, venation, phyllotaxy
- Inflorescence
- Symmetry, ovary position
- Aestivation, placentation
- Pericarp layers, drupe
- Dicot seed
- Monocot seed
- Fabaceae
- Solanaceae
- Liliaceae
12. Tips and Tricks
- Placentation: "Pea Marginal, Mustard Parietal" (letters swap), "Sunflower Basal (sits at the bottom)", "Dianthus Free central".
- Stamen bundles: mono = china rose (one tube around the style), di = pea (9 + 1), poly = citrus.
- Epipetalous → petals (brinjal, Solanaceae); epiphyllous → perianth (lily, Liliaceae).
- Vegetative propagation stems: Runner – grass; Stolon – mint; Offset – Pistia; Sucker – banana ("RSOS").
- Calling sweet potato a stem (it is an adventitious root) and potato a root (it is a stem tuber).
- Calling pea tendrils stem tendrils (they are modified leaflets).
- Saying mustard has axile placentation (it is parietal with a false septum).
- Thinking a perigynous ovary is inferior (it is half-inferior).
- Saying Fabaceae stamens are monoadelphous (they are diadelphous, 9 + 1).
13. Important One-liners
- Root hairs arise from the region of maturation.
- Pneumatophores help Rhizophora get oxygen in swampy soil.
- Opuntia has a flattened green stem (phylloclade).
- In Australian acacia, the petiole becomes green and leaf-like (phyllode).
- Alstonia shows whorled phyllotaxy.
- Canna flowers are asymmetric.
- Lotus and rose have apocarpous gynoecium.
- Mango and coconut fruits are drupes.
- The scutellum is the single cotyledon of maize.
- The aleurone layer is proteinous.
- Colchicine is obtained from Colchicum autumnale (Liliaceae).
- Ashwagandha and belladonna belong to Solanaceae.
14. NEET-pattern Questions with Detailed Answers
These questions are original and based on concepts that NEET UG asks again and again.
Pneumatophores are found in:
- Banyan
- Maize
- Rhizophora
- Carrot
Show solution
Plants of swampy areas, such as Rhizophora, have roots that grow upwards out of the soil to get oxygen. Banyan has prop roots, maize has stilt roots, and carrot has a storage tap root.
Answer: (C)
Vexillary aestivation is characteristic of:
- Solanaceae
- Fabaceae
- Liliaceae
- Brassicaceae
Show solution
In Fabaceae, the standard petal overlaps the wings, which overlap the keel. This is vexillary (papilionaceous) aestivation. Solanaceae and Liliaceae show valvate aestivation.
Answer: (B)
Which of the following is a stem modification?
- Sweet potato
- Carrot
- Ginger
- Turnip
Show solution
Ginger is a rhizome with nodes, internodes and buds, so it is a stem. Sweet potato is an adventitious storage root, and carrot and turnip are tap storage roots.
Answer: (C)
The placentation in mustard is:
- Axile
- Marginal
- Parietal
- Free central
Show solution
In mustard, ovules develop on the inner wall of a one-chambered ovary, which becomes two-chambered due to a false septum. This is parietal placentation. Axile is seen in china rose, marginal in pea, and free central in Dianthus.
Answer: (C)
An inferior ovary is found in:
- Mustard
- Brinjal
- Guava
- Plum
Show solution
Guava has an epigynous flower in which the thalamus encloses and fuses with the ovary, making it inferior. Mustard and brinjal are hypogynous (superior ovary), and plum is perigynous (half-inferior).
Answer: (C)
Epipetalous stamens are found in:
- Lily
- Brinjal
- Pea
- China rose
Show solution
Brinjal (Solanaceae) has stamens attached to the petals. Lily has epiphyllous stamens attached to the perianth. Pea has diadelphous stamens, and china rose has monoadelphous stamens.
Answer: (B)
Assertion (A): Potato is a modified stem.
Reason (R): Potato tubers bear "eyes", which are nodes bearing buds.
- Both A and R are true, and R explains A
- Both A and R are true, but R does not explain A
- A is true, R is false
- A is false, R is true
Show solution
The presence of nodes with buds is what identifies a stem. The "eyes" of a potato are such nodes, so R explains A.
Answer: (A)
The floral formula ⊕ ⚥ P(3+3) A3+3 G(3) belongs to:
- Fabaceae
- Solanaceae
- Liliaceae
- Brassicaceae
Show solution
A perianth of six tepals, six stamens in two whorls and a tricarpellary syncarpous superior ovary are features of Liliaceae. Fabaceae is zygomorphic with K(5); Solanaceae has K(5) C(5) and a bicarpellary ovary; Brassicaceae has K2+2 C4.
Answer: (C)
Which pair is incorrectly matched?
- Twisted aestivation — china rose
- Imbricate aestivation — Cassia
- Valvate aestivation — Calotropis
- Basal placentation — Dianthus
Show solution
Dianthus has free central placentation. Basal placentation is seen in sunflower and marigold. The other three pairs are correct.
Answer: (D)
Match: (a) Offset (b) Phyllode (c) Sucker (d) Phylloclade — (i) Australian acacia (ii) Opuntia (iii) Pistia (iv) Banana.
- a-iii, b-i, c-iv, d-ii
- a-iv, b-i, c-iii, d-ii
- a-iii, b-ii, c-iv, d-i
- a-i, b-iii, c-iv, d-ii
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Pistia propagates by offsets, Australian acacia has phyllodes (green petioles), banana forms suckers, and Opuntia has a phylloclade (flattened green stem).
Answer: (A)
15. Quick Revision Summary
- Root: tap / fibrous / adventitious; regions — cap, meristematic, elongation, maturation (root hairs); modifications for storage, support (prop, stilt) and respiration (pneumatophores).
- Stem: nodes, internodes, buds; modifications — tuber, rhizome, corm, tendril, thorn, phylloclade, runner, stolon, offset, sucker.
- Leaf: base, petiole, lamina; reticulate vs parallel; simple vs compound (pinnate — neem, palmate — silk cotton); phyllotaxy alternate, opposite, whorled; modifications — tendril, spine, phyllode, pitcher.
- Inflorescence: racemose (acropetal) vs cymose (basipetal).
- Flower: symmetry; hypo-, peri-, epigynous; aestivation (valvate, twisted, imbricate, vexillary); androecium (epipetalous, epiphyllous, mono-/di-/polyadelphous); gynoecium (apo-/syncarpous); placentation (marginal, axile, parietal, free central, basal).
- Fruit: ripened ovary; drupe. Seed: dicot (testa, tegmen, hilum, micropyle) vs monocot (scutellum, aleurone, coleoptile, coleorhiza).
- Families: Fabaceae (zygomorphic, diadelphous, legume), Solanaceae (epipetalous, persistent calyx, berry), Liliaceae (perianth, epiphyllous, trilocular, capsule).