Morphology of Flowering Plants | NEET Biology Revision Notes PDF

Morphology of Flowering Plants | NEET Revision Notes

Target Audience: NEET UG Aspirants | Source: XI NCERT- Biology Book and Practical Book

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1. Fundamental Botanical History

Katherine Esau:
- Discovered that the curly top virus spreads through the food-conducting phloem tissue.
- Published Plant Anatomy (1954), bringing a dynamic, developmental approach to plant structure.
- Published Anatomy of Seed Plants (1960), referred to as the "Webster's of plant biology".
- Sixth woman elected to the National Academy of Sciences (1957).
- Recipient of the National Medal of Science (1989).

2. Root System & Modifications

Primary Root Development: Formed by the direct elongation of the radicle in the majority of dicotyledonous plants.

Root Regions (Distal to Proximal)

Root Cap: Thimble-like structure protecting the tender apex.
Region of Meristematic Activity: Cells are very small, thin-walled, with dense protoplasm; divide repeatedly.
Region of Elongation: Cells undergo rapid elongation/enlargement; responsible for root growth in length.
Region of Maturation: Cells gradually differentiate and mature; epidermal cells form delicate root hairs for water/mineral absorption.

Root Types & Examples

Tap Root: Primary root + branches (e.g., Mustard).
Fibrous Root: Primary root is short-lived; roots originate from the base of the stem (e.g., Wheat).
Adventitious Root: Arise from parts other than the radicle (e.g., Grass, Monstera, Banyan).

Table: Root Modifications for Specialized Functions

Modification Type	Function	Examples	Distinguishing Features
Fusiform / Spindle	Storage	Radish	Tap root modification
Napiform / Top-shaped	Storage	Turnip, Beet	Tap root modification
Conical	Storage	Carrot	Tap root modification
Indefinite Shape	Storage	Sweet potato, Dahlia, Asparagus, Portulaca	Adventitious root modification
Nodulated Roots	N-Fixation	Pea, Legumes	Contains symbiotic Rhizobium; active nodules are pink
Prop Roots	Mechanical Support	Banyan	Aerial adventitious roots growing vertically/obliquely downward
Stilt Roots	Mechanical Support	Maize, Sugarcane	Arise from basal nodes of the stem
Climbing Roots	Mechanical Support	Betel, Black pepper	Arise from nodes and internodes
Pneumatophores	Gaseous Exchange	Rhizophora mangle	Found in mangroves/swamps; erect peg-like structures with numerous pores

3. Stem System & Modifications (NCERT Practical Book Content)

Origin: Develops from the plumule of the germinating seed embryo.
Characteristics: Bears nodes, internodes, and terminal/axillary buds.

Table: Stem Modifications for Specialized Functions

Type	Sub-type	Function	Examples	Distinct Features
Underground	Tuber	Storage	Potato	Non-green; presence of an 'eye' which represents a node
Underground	Rhizome	Storage	Ginger	Presence of distinct nodes, internodes, and scaly leaves
Underground	Bulb	Storage	Onion, Garlic	Highly reduced stem with a basal cluster of roots
Underground	Corm	Storage	Yam, Arum (Arbi)	Fleshy underground stem
Subaerial	Runner	Veg. Propagation	Cynodon dactylon, Oxalis	Slender prostrate branches arising from axillary buds
Subaerial	Stolon	Veg. Propagation	Mint, Strawberry	Slender lateral branch from the base grows upward, then arches down
Subaerial	Offset	Veg. Propagation	Eichhornia, Pistia	Single horizontal internode; tuft of leaves above, root cluster below
Subaerial	Sucker	Veg. Propagation	Chrysanthemum, Banana, Pineapple	Arises from underground stem, grows obliquely upward
Aerial	Thorn	Protection	Acacia, Bougainvillea, Citrus, Pomegranate, Duranta, Ber, Prosopis	Hard, pointed structures; modified axillary branch
Aerial	Tendril	Support (Climbing)	Vitis, Passion flower, Bignonia	Spirally coiled for support
Aerial	Phylloclade	Photosynthesis	Cactus (Opuntia)	Flattened/cylindrical green stem of unlimited growth

4. Leaf Morphology & Modifications

Origin: Develops exogenously at the node; originates from shoot apical meristems.
Arrangement: Arranged in an acropetal order.
Parts:
- Leaf base: May bear lateral stipules.
- Petiole: Long, thin, flexible; cools leaf by fluttering.
- Lamina: Contains veins/veinlets for rigidity and transport.
Pulvinus: Swollen leaf base found in some leguminous plants.
Sheathing Leaf Base: Expands to cover the stem partially or wholly in monocotyledons.

Table: Leaf Venation, Types, & Phyllotaxy

Category	Type	Description	NCERT Examples
Venation	Reticulate	Veinlets form a network (typical of Dicots)	Dicotyledonous plants
Venation	Parallel	Veins run parallel (typical of Monocots)	Monocotyledons
Compound Leaf	Pinnately	Leaflets present on a common axis (rachis)	Neem
Compound Leaf	Palmately	Leaflets attached at a common point (petiole tip)	Silk cotton
Phyllotaxy	Alternate	Single leaf arises at each node	China rose, Mustard, Sunflower
Phyllotaxy	Opposite	Pair of leaves arise at each node	Calotropis, Guava
Phyllotaxy	Whorled	More than two leaves arise at a node	Alstonia

Leaf Modifications

Spines: For protection and checking transpiration (e.g., Cactus, Argemone).
Tendrils: Long, slender, spirally coiled for support (e.g., Sweet pea, Lentil).
Fleshy Leaves: For food storage (e.g., Onion, Garlic).
Insectivorous: Modified to trap insects (e.g., Pitcher plant / Nepenthes, Bladderwort / Utricularia).

5. Inflorescence (Comparisons) (NCERT Practical Book Content)

Solitary Flower: Whenever a shoot tip transforms into a flower, it is always solitary.

Table: Inflorescence Classification

Type	Sub-Type / Form	Key Characteristics	NCERT Examples
Racemose	Simple Raceme	Unbranched main axis, pedicellate flowers in acropetal succession	Mustard, Radish, Crotalaria
Racemose	Spike	Sessile flowers borne on an elongated axis	Amaranth
Racemose	Catkin	Pendulous main axis bearing unisexual sessile flowers	Mulberry
Racemose	Spadix	Fleshy peduncle covered by long showy bract	Banana, Colocasia
Racemose	Corymb	Shorter raceme; lower pedicels longer, bringing all flowers to the same level	Cassia auriculata, Gynandropsis, Candytuft
Racemose	Umbel	Extremely reduced main axis; cluster of pedicellate flowers with equal stalks	Coriander, Allium cepa (Onion)
Racemose	Capitulum (Head)	Sessile flowers borne in a dense cluster on a flattened receptacle	Sunflower
Racemose	Panicle	Compound raceme (branched main axis)	Mango, Drumstick
Cymose	Monochasial	Peduncle ends in a single flower; single flower arises in axil	Hibiscus rosasinensis
Cymose	Dichasial	Three flowers; older central, two lateral younger below	Jasminum
Cymose	Polychasial	Main axis ends in a flower; >2 branches arise below terminal flower	Calotropis
Special	Intercalary	Terminal clusters left behind by continuing apical growth	Callistemon (Bottle brush)
Special	Cauliflory	Inflorescences develop on older branches	Cocoa plant (Theobroma cacao), Jackfruit (Artocarpus), Cannon ball tree

6. Floral Morphology & Appendages

A. Floral Symmetry

Actinomorphic (Radial): Divisible into two equal radial halves in any radial plane (e.g., Mustard, Datura, Chilli).
Zygomorphic (Bilateral): Divisible into two similar halves only in one particular vertical plane (e.g., Pea, Gulmohur, Bean, Cassia).
Asymmetric (Irregular): Cannot be divided into similar halves by any plane (e.g., Canna).

B. Insertion of Floral Leaves (Ovary Position)

Hypogynous (Superior Ovary): Gynoecium occupies highest position (e.g., Mustard, China rose, Brinjal).
Perigynous (Half-Inferior Ovary): Gynoecium in the centre, other parts on the thalamus rim at the same level (e.g., Plum, Rose, Peach).
Epigynous (Inferior Ovary): Thalamus margin grows upward, enclosing and fusing with the ovary (e.g., Guava, Cucumber, Ray florets of sunflower).

C. Aestivation (Arrangement of Sepals/Petals)

Valvate: Margins touch without overlapping (e.g., Calotropis).
Twisted: One margin overlaps the next (e.g., China rose, Lady's finger, Cotton).
Imbricate: Margins overlap but not in any particular direction (e.g., Cassia, Gulmohur).
Vexillary (Papilionaceous): Largest petal (standard) overlaps two lateral petals (wings) which overlap two smallest anterior petals (keel) (e.g., Pea, Bean).

D. Androecium Details

Epipetalous: Stamens attached to petals (e.g., Brinjal).
Epiphyllous: Stamens attached to perianth (e.g., Lily).
Monoadelphous: United into one bunch (e.g., China rose).
Diadelphous: United into two bundles (e.g., Pea).
Polyadelphous: United into more than two bundles (e.g., Citrus).
Filament length variation: Present within the same flower in Salvia and Mustard.

E. Gynoecium & Placentation (Arrangement of Ovules)

Apocarpous: Carpels are free (e.g., Lotus, Rose).
Syncarpous: Carpels are fused (e.g., Mustard, Tomato).
Marginal: Placenta forms a ridge along the ventral suture, ovules in two rows (e.g., Pea).
Axile: Ovules attached to an axial placenta in a multilocular ovary (e.g., China rose, Tomato, Lemon).
Parietal: Ovules develop on the inner wall/peripheral part; 1-chambered ovary becomes 2-chambered due to a false septum (e.g., Mustard, Argemone).
Free Central: Ovules on central axis, septa are absent (e.g., Dianthus, Primrose).
Basal: Placenta develops at the base, single ovule attached (e.g., Sunflower, Marigold).

7. Fruit & Seed Characteristics

Parthenocarpic Fruit: Formed without fertilization.
Drupe: Develops from monocarpellary superior ovaries, one-seeded (e.g., Mango, Coconut).
- Mango: Epicarp (outer thin), Mesocarp (fleshy edible), Endocarp (stony hard).
- Coconut: Mesocarp is fibrous.

Dicotyledonous Seed

Seed Coat: Outer testa, inner tegmen.
Hilum: Scar of attachment to the fruit.
Exceptions in Endosperm: Endospermic (Castor), Non-endospermous (Bean, Gram, Pea).

Monocotyledonous Seed

Exceptions: Generally endospermic, but Orchids are non-endospermic.
Maize Seed Anatomy:
- Membranous seed coat fused with fruit wall.
- Aleurone layer (proteinous covering separating embryo from bulky endosperm).
- Scutellum (large, shield-shaped single cotyledon).
- Coleoptile (plumule sheath).
- Coleorhiza (radicle sheath).

8. Family Solanaceae ("Potato Family")

Vegetative Features

Mostly herbs/shrubs (rarely small trees).
Stem: Herbaceous (rarely woody), aerial, erect, cylindrical, solid/hollow, hairy/glabrous; underground stem in Solanum tuberosum.
Leaves: Alternate, simple, exstipulate with reticulate venation.

Floral Features

Inflorescence: Solitary, axillary or cymose (Solanum).
Flower: Bisexual, actinomorphic.
Calyx/Corolla: 5, united, valvate aestivation.
Androecium: Stamens 5, epipetalous.
Gynoecium: Bicarpellary, obliquely placed, syncarpous, superior ovary, bilocular, swollen placenta with many ovules (axile).
Fruit/Seed: Berry or capsule; seeds many, endosperms.

Economic Importance

Food: Tomato, Brinjal, Potato.
Spice: Chilli.
Medicine: Belladonna, Ashwagandha.
Fumigatory: Tobacco.
Ornamental: Petunia.

9. EXTRA FAMILIES (NEET Syllabus 2024 onwards)

1. Family Hierarchy and Key Rankings

Family	Class	Order	Economic / Ecological Status
Malvaceae (Cotton)	Dicotyledonae	Malvales	Most economically important fibre-yielding plants.
Cruciferae (Mustard)	Dicotyledonae	Parietales	High food/oil yield; noted for pungent smell.
Leguminosae (Legumes)	Dicotyledonae	Rosales	Major source of pulses, dyes, and fodder.
Asteraceae (Sunflower)	Dicotyledonae	Asterales	Largest family of angiosperms; most advanced.
Poaceae (Grasses)	Monocotyledonae	Poales	5th largest family; most economically important globally (cereals).

2. Family-Specific Details

A. Malvaceae (Cotton Family)

Androecium: Indefinite stamens, monadelphous (filaments united into a single long staminal tube), epipetalous, with monothecous anthers.
Gynoecium: Multicarpellary (specifically pentacarpellary and syncarpous in Hibiscus), multilocular, with axile placentation.
Aestivation: Calyx is valvate; Corolla is twisted or imbricate.
Fruit & Seed: Capsule or berry; seeds are endospermic.
Crucial Examples:
- Cotton (Gossypium sp.): Fibre is obtained strictly from the seed coat (seed hairs/trichomes).
- Madras Hemp (Hibiscus cannabinus): Used in the rope industry.
- Okra/Bhindi (Abelmoschus esculentus).

B. Cruciferae / Brassicaceae (Mustard Family)

Corolla: 4 clawed petals, cruciform (crosswise) arrangement, valvate aestivation.
Androecium: 6 stamens, tetradynamous condition (arrangement: 2 short outer, 4 long inner).
Gynoecium: Bicarpellary, syncarpous, parietal placentation.
Exception/Anomaly: Ovary is initially unilocular but becomes bilocular due to a false septum called the replum.
Fruit & Seed: Siliqua or silicula; seeds are non-endospermic.
Crucial Examples & Compounds: Contains singrin (a sulphur-containing glycoside) responsible for the pungent smell of mustard oil. Brassica oleracea var. capitata (Cabbage) & var. botrytis (Cauliflower).

C. Leguminosae (Divided into 3 Sub-families)

Vegetative Anomaly: Roots possess root nodules (nitrogen fixation); leaves are alternate with a pulvinate (swollen) base.

Feature	Fabaceae (Papilionoideae)	Caesalpinioideae	Mimosoideae
Inflorescence	Racemose (Raceme)	Raceme, umbel, or solitary	Head, capitulum, or spike
Flower Symmetry	Zygomorphic, butterfly-shaped	Zygomorphic	Actinomorphic
Corolla	Papilionaceous, vexillary aestivation	Ascending imbricate aestivation	Membranous, valvate aestivation
Androecium	10, diadelphous, dithecous	10 stamens	Indefinite, polyandrous
Fruit	Legume	Legume	Lomentum
Examples	Pulses, Soyabean, Indigofera, Sesbania, Mulethi	Tamarind, Gulmohur, Ashok, Amaltas	Touch-me-not (Mimosa pudica)

D. Compositae / Asteraceae (Sunflower Family)

Inflorescence: Capitulum or Head.
Distinctive Floral Features (Epigynous Flowers):
- Calyx Anomaly: Modified into a hairy/scaly, persistent structure called Pappus.
- Placentation: Unilocular with basal placentation.
Florets Differentiation:
- Ray Florets: Unisexual (pistillate), zygomorphic. Androecium is absent.
- Disc Florets: Bisexual, actinomorphic. Androecium has 5 stamens, epipetalous, syngenesious (anthers fused, filaments free), dithecous.
Fruit & Seed: Cypsela; Non-endospermic.
Crucial Examples & Compounds:
- Pyrethrum: Commercial insecticide extracted from Chrysanthemum inflorescence.
- Santonin: Drug prepared from Artemisia annua flowers, used to remove parasitic worms.
- Parthenium: Carrot grass / Congress grass (widespread invasive weed).

E. Graminae / Poaceae (Grass Family)

Vegetative Features: Monocotyledons; fibrous roots; sheathing leaf base without petiole (sessile).
Distinctive Floral Features:
- Inflorescence: Spikelet.
- Flower: Bracteate, zygomorphic. Usually bisexual (Rice) but rarely unisexual (Maize/Corn - Zea mays).
- Perianth Anomaly: Reduced to two small scales known as lodicules.
- Gynoecium: Monocarpellary, superior, unilocular with a single ovule; basal placentation.
Fruit & Seed: Caryopsis (single-seeded fruit where fruit wall is completely fused with seed coat); seeds are endospermic.
Crucial Examples: Rice (Oryza sativa), Wheat (Triticum aestivum), Maize (Zea mays) – contribute maximum to global food production. Sugarcane (Saccharum officinarum) – major source of sugar.

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Morphology of Flowering Plant