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Morphology of Flowering Plants – Class 11 Biology Chapter 5 Notes & NCERT PDF

Class 11BiologyChapter 5NCERT book: Biology - Class 11

Notes and a simple summary of Chapter 5 of the NCERT Class 11 Biology book, with the official chapter PDF, flashcards, an MCQ quiz and an AI tutor for your doubts.

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Chapter 5: Morphology of Flowering Plants

Introduction

Chapter 5 begins Unit 2, Structural Organisation in Plants and Animals. The unit opener honours Katherine Esau (1898–1997), whose Plant Anatomy (1954) and The Anatomy of Seed Plants (1960) revived plant anatomy. Angiosperms show huge diversity in external structure (morphology) but all have roots, stems, leaves, flowers and fruits. The underground part is the root system; the part above ground is the shoot system. Standard technical terms are needed to describe and classify plants.

Key Concepts

5.1 The Root

  • Tap root system — direct elongation of the radicle forms the primary root with lateral roots (secondary, tertiary…); typical of dicots, e.g., mustard.
  • Fibrous root system — in monocots the primary root is short-lived and replaced by many roots from the base of the stem, e.g., wheat.
  • Adventitious roots — arise from parts other than the radicle, e.g., *grass, Monstera, banyan*.
  • Functions: absorption of water and minerals, anchorage, storing reserve food, synthesis of plant growth regulators.

    • 5.1.1 Regions of the root

  • Root cap — thimble-like; protects the tender apex.
  • Region of meristematic activity — small, thin-walled cells with dense protoplasm; divide repeatedly.
  • Region of elongation — rapid elongation and enlargement; growth in length.
  • Region of maturation — cells differentiate; some epidermal cells form root hairs that absorb water and minerals.

    • 5.2 The Stem

  • Ascending axis bearing branches, leaves, flowers and fruits; develops from the plumule.
  • Has nodes (where leaves arise) and internodes (between nodes); bears terminal or axillary buds.
  • Functions: spreading out branches, conducting water, minerals and photosynthates; some stems store food, support, protect or help vegetative propagation.

    • 5.3 The Leaf

  • Lateral, flattened structure at the node with a bud in its axil; originates from shoot apical meristem in acropetal order; main organ of photosynthesis.
  • Parts: leaf base, petiole, lamina; may have stipules. In monocots the leaf base forms a sheath; in some legumes the swollen leaf base is the pulvinus. Long flexible petioles let blades flutter, cooling the leaf. Midrib and veins give rigidity and transport.
  • 5.3.1 Venation: reticulate (network — most dicots) and parallel (most monocots).
  • 5.3.2 Types of leaves: simple (incisions don't reach midrib) and compound (incisions reach midrib forming leaflets). A bud is in the axil of the petiole, not of leaflets.

    • - Pinnately compound — leaflets on a common axis, the rachis (neem).

    - Palmately compound — leaflets at the tip of the petiole (silk cotton).

  • 5.3.3 Phyllotaxy (arrangement of leaves):

    • - Alternate — one leaf per node: china rose, mustard, sunflower.

    - Opposite — pair per node: Calotropis, guava.

    - Whorled — more than two per node: Alstonia.

    5.4 The Inflorescence

  • A flower is a modified shoot (shoot apical meristem → floral meristem). Arrangement of flowers on the floral axis = inflorescence.
  • Racemose — main axis continues to grow; flowers lateral in acropetal succession.
  • Cymose — main axis ends in a flower (limited growth); flowers in basipetal order.

    • 5.5 The Flower

  • Reproductive unit for sexual reproduction. Four whorls on the thalamus (receptacle): calyx, corolla (accessory) and androecium, gynoecium (reproductive). When calyx and corolla are not distinct (lily) → perianth.
  • Bisexual (both androecium and gynoecium) vs unisexual.
  • Symmetry: actinomorphic (radial — mustard, datura, chilli); zygomorphic (bilateral — pea, gulmohur, bean, Cassia); asymmetric (canna).
  • Trimerous / tetramerous / pentamerous — parts in multiples of 3, 4, 5. Bracteate (with bracts) vs ebracteate.
  • Position of ovary:

    • - Hypogynous — ovary superior (mustard, china rose, brinjal).

    - Perigynous — ovary half inferior (plum, rose, peach).

    - Epigynous — ovary inferior (guava, cucumber, ray florets of sunflower).

    5.5.1 Parts of a flower

  • Calyx (sepals) — gamosepalous or polysepalous; protects the bud.
  • Corolla (petals) — gamopetalous or polypetalous; tubular, bell-, funnel- or wheel-shaped.
  • Aestivation (arrangement of sepals/petals in the bud):

    • - Valvate — margins just touch (Calotropis).

    - Twisted — each overlaps the next (china rose, lady's finger, cotton).

    - Imbricate — overlap in no particular direction (Cassia, gulmohur).

    - Vexillary / papilionaceous — standard overlaps two wings which overlap two keel petals (pea, bean).

  • Androecium — stamens (filament + anther; bilobed anther, each lobe with two pollen sacs); sterile stamen = staminode. Epipetalous (brinjal); epiphyllous (lily); polyandrous (free); monoadelphous (china rose), diadelphous (pea), polyadelphous (citrus). Varying filament length (Salvia, mustard).
  • Gynoecium — carpels (stigma, style, ovary); ovules on a placenta. Apocarpous (free carpels — lotus, rose) vs syncarpous (fused — mustard, tomato).
  • Placentation:

    • - Marginal — ridge along ventral suture, two rows (pea).

    - Axile — axial placenta in multilocular ovary (china rose, tomato, lemon).

    - Parietal — on inner wall; one-chambered ovary becomes two-chambered by a false septum (mustard, Argemone).

    - Free central — central axis, no septa (Dianthus, primrose).

    - Basal — at base, single ovule (sunflower, marigold).

    5.6 The Fruit

  • Mature/ripened ovary after fertilisation; without fertilisation = parthenocarpic fruit.
  • Pericarp (dry or fleshy) — epicarp, mesocarp, endocarp.
  • Drupe — from monocarpellary superior ovary, one-seeded: mango (thin epicarp, fleshy edible mesocarp, stony endocarp) and coconut (fibrous mesocarp).

    • 5.7 The Seed

  • Ovules develop into seeds: seed coat + embryo (radicle, embryonal axis, one or two cotyledons).
  • Dicot seed (5.7.1): seed coat of testa (outer) and tegmen (inner); hilum (scar), micropyle (pore); two fleshy cotyledons; radicle and plumule. Endospermic — castor; non-endospermous — bean, gram, pea.
  • Monocot seed (5.7.2): generally endospermic (orchids non-endospermic). In maize: seed coat fused with fruit wall; bulky endosperm; proteinous aleurone layer; embryo with one shield-shaped cotyledon — scutellum; plumule in coleoptile, radicle in coleorhiza.

    • 5.8 Semi-technical description and floral formula

  • Describe in sequence: habit → root, stem, leaves → inflorescence and flower parts → floral diagram and floral formula.
  • Symbols: Br bracteate, K calyx, C corolla, P perianth, A androecium, G gynoecium (line below G = superior ovary, above = inferior), ⊕ actinomorphic; fusion shown by brackets, adhesion by a line above symbols.
  • Floral diagram shows the mother axis as a dot on top, whorls from calyx (outermost) to gynoecium (centre).
  • Book example: mustard (Brassicaceae) — ⊕ K2+2 C4 A2+4 G(2).

    • 5.9 Solanaceae (potato family)

  • Herbs, shrubs, rarely small trees; stem herbaceous, rarely woody; underground stem in potato (Solanum tuberosum); leaves alternate, simple, rarely pinnately compound, exstipulate, reticulate.
  • Inflorescence solitary, axillary or cymose; flower bisexual, actinomorphic.
  • Calyx: five sepals, united, persistent, valvate. Corolla: five petals, united, valvate. Androecium: five stamens, epipetalous. Gynoecium: bicarpellary, obliquely placed, syncarpous, superior, bilocular, swollen placenta, axile.
  • Fruit: berry or capsule; seeds many, endospermous.
  • Importance: food (tomato, brinjal, potato), spice (chilli), medicine (belladonna, ashwagandha), fumigatory (tobacco), ornamental (petunia).

    • Diagrams to Know

  • Figure 5.3 regions of the root tip; Figure 5.4 parts of a leaf, reticulate and parallel venation; Figure 5.11 aestivation types; Figure 5.12 placentation types; Figure 5.14 dicot seed (gram); Figure 5.15 monocot seed (maize, V.S.); Figure 5.16 mustard floral diagram; Figure 5.17 Solanum nigrum.

    • Key-Facts Sheet

  • Tap — mustard; fibrous — wheat; adventitious — banyan, Monstera, grass.
  • Pinnate — neem; palmate — silk cotton.
  • Alternate — china rose; opposite — guava; whorled — Alstonia.
  • Twisted — china rose; vexillary — pea.
  • Monoadelphous — china rose; diadelphous — pea; polyadelphous — citrus.
  • Parietal — mustard; basal — sunflower; free central — Dianthus.

    • Exam Focus

  • Q: Differentiate racemose and cymose inflorescence. Racemose: main axis grows continuously, flowers lateral, acropetal. Cymose: main axis ends in a flower, limited growth, basipetal.
  • Q: Semi-technical description of a Solanaceae flower with floral diagram — use the 5.9 list above; draw five united sepals and petals, five epipetalous stamens, bicarpellary obliquely placed ovary with axile placentation.
  • Q: Describe the types of placentation — the five types with examples above.
  • Q: Label V.S. of maize seed — seed coat & fruit wall, endosperm, aleurone layer, scutellum, coleoptile, plumule, radicle, coleorhiza.

    • Key Terms

  • Tap root (मूसला जड़)
  • Adventitious root (अपस्थानिक जड़)
  • Node (पर्वसंधि / गाँठ)
  • Phyllotaxy (पर्णविन्यास)
  • Venation (शिराविन्यास)
  • Inflorescence (पुष्पक्रम)
  • Aestivation (पुष्पदल विन्यास)
  • Placentation (बीजांडन्यास)
  • Epipetalous (दललग्न)
  • Hypogynous (जायांगधर)
  • Pericarp (फलभित्ति)
  • Parthenocarpy (अनिषेकफलन)
  • Scutellum (स्कुटेलम / वरुथिका)
  • Aleurone layer (एल्यूरोन परत)
  • Floral formula (पुष्प सूत्र)

    • Common Mistakes

  • Mixing acropetal (racemose) with basipetal (cymose) order.
  • Calling the ovary of guava superior — it is inferior (epigynous).
  • Writing twisted aestivation for pea — pea is vexillary.
  • Forgetting that a bud is present in the axil of the petiole, not of leaflets, in compound leaves.
  • Describing the Solanaceae ovary as inferior — it is superior, bicarpellary and obliquely placed.

    • 💡 Key Learning Points

    • ✓Roots may be tap, fibrous or adventitious; the root tip has root cap and zones of meristematic activity, elongation and maturation.
    • ✓Leaves vary in venation (reticulate, parallel), type (simple, pinnately or palmately compound) and phyllotaxy (alternate, opposite, whorled).
    • ✓Inflorescence is racemose or cymose; flowers vary in symmetry, ovary position, aestivation, stamen union and placentation.
    • ✓Fruits develop from ovaries (drupes like mango and coconut) and seeds from ovules; dicot and monocot seeds differ in cotyledons and endosperm.
    • ✓Plants are described semi-technically with floral diagrams and floral formulae, illustrated by the family Solanaceae.

    👨‍🏫 Teaching Tips

    • →Uproot a mustard or weed plant and a wheat/grass plant to compare tap and fibrous roots directly.
    • →Collect leaves of neem, silk cotton, china rose, guava and Alstonia for a hands-on sorting of leaf types and phyllotaxy.
    • →Dissect a china rose or Datura/brinjal flower whorl by whorl and have students write its floral formula.
    • →Cut ovaries of pea, tomato/lemon, mustard and sunflower transversely to show placentation types.
    • →Soak gram and maize seeds overnight and let students identify hilum, micropyle, cotyledons, scutellum and coleoptile.
    • →Practise drawing floral diagrams with the mother axis dot at the top.
    • →Show a mango and coconut cut open to identify epicarp, mesocarp and endocarp in drupes.

    📋 Assessment Questions

    1. Can the student distinguish tap, fibrous and adventitious roots with examples?
    2. Can the student identify aestivation and placentation types from diagrams?
    3. Can the student explain hypogynous, perigynous and epigynous flowers with examples?
    4. Can the student label a gram seed and V.S. of maize seed?
    5. Can the student write the semi-technical description of a Solanaceae flower?

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    Keep learning

    All chapters in Biology - Class 11

    1. 1. The Living World
    2. 2. Biological Classification
    3. 3. Plant Kingdom
    4. 4. Animal Kingdom
    5. 5. Morphology of Flowering Plants
    6. 6. Anatomy of Flowering Plants
    7. 7. Structural Organisation in Animals
    8. 8. Cell: The Unit of Life
    9. 9. Biomolecules
    10. 10. Cell Cycle and Cell Division
    11. 11. Photosynthesis in Higher Plants
    12. 12. Respiration in Plants
    13. 13. Plant Growth and Development
    14. 14. Breathing and Exchange of Gases
    15. 15. Body Fluids and Circulation
    16. 16. Excretory Products and their Elimination
    17. 17. Locomotion and Movement
    18. 18. Neural Control and Coordination
    19. 19. Chemical Coordination and Integration