Morphology of Flowering Plants
NCERT Class 11 Biology • Chapter 5 Solutions
Leaf & Phyllotaxy
1. How is a pinnately compound leaf different from a palmately compound leaf?
[Image of pinnately vs palmately compound leaf]
| Feature | Pinnately Compound Leaf | Palmately Compound Leaf |
|---|---|---|
| Rachis | Leaflets are present on a common axis called the rachis. | Leaflets are attached at a common point (tip of petiole). Rachis is absent. |
| Arrangement | Leaflets are arranged laterally along the rachis. | Leaflets radiate outwards like fingers from a palm. |
| Example | Neem | Silk Cotton |
2. Explain with suitable examples the different types of phyllotaxy.
Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. There are three main types:
- Alternate: A single leaf arises at each node in an alternate manner.
Examples: China rose, Mustard, Sunflower. - Opposite: A pair of leaves arise at each node and lie opposite to each other.
Examples: Calotropis, Guava. - Whorled: More than two leaves arise at a node and form a whorl.
Example: Alstonia.
Floral Terms & Differences
3. Define the following terms.
- (a) Aestivation: The mode of arrangement of sepals or petals in a floral bud with respect to the other members of the same whorl.
- (b) Placentation: The arrangement of ovules within the ovary.
- (c) Actinomorphic: A flower that can be divided into two equal radial halves in any radial plane passing through the center (Radial symmetry). e.g., Mustard.
- (d) Zygomorphic: A flower that can be divided into two similar halves only in one particular vertical plane (Bilateral symmetry). e.g., Pea.
- (e) Superior Ovary: The ovary is situated highest, above the other floral parts (Hypogynous flower). e.g., Brinjal.
- (f) Perigynous Flower: The gynoecium is situated in the center and other parts are located on the rim of the thalamus almost at the same level. Ovary is half-inferior. e.g., Rose.
- (g) Epipetalous Stamen: A condition where stamens are attached to the petals. e.g., Brinjal.
4. Differentiate between Racemose/Cymose and Apocarpous/Syncarpous.
(a) Racemose vs Cymose Inflorescence
| Feature | Racemose | Cymose |
|---|---|---|
| Main Axis | Continues to grow. | Terminates in a flower (Limited growth). |
| Order | Flowers borne laterally in acropetal succession (younger at tip). | Flowers borne in basipetal succession (older at tip). |
(b) Apocarpous vs Syncarpous Ovary
| Feature | Apocarpous | Syncarpous |
|---|---|---|
| Carpels | Carpels are free (not fused). | Carpels are fused together. |
| Example | Lotus, Rose. | Mustard, Tomato. |
Diagrams & Descriptions
5. Draw the labelled diagram of Gram seed and Maize seed V.S.
(i) Gram Seed: Dicot seed. Labels should include: Seed coat (Testa), Hilum, Micropyle, Cotyledons, Embryonal axis (Radicle, Plumule).
(ii) Maize Seed V.S.: Monocot seed. Labels should include: Pericarp fused with Seed coat, Endosperm (bulky), Aleurone layer (proteinous), Scutellum (shield-shaped cotyledon), Coleoptile (covering plumule), Coleorhiza (covering radicle).
6. Description and Floral Diagram of Family Solanaceae.
Semi-Technical Description (Solanaceae)
- Habit: Herbs, shrubs, or small trees.
- Flower: Bisexual, Actinomorphic.
- Calyx: 5 Sepals, united (gamosepalous), persistent, valvate aestivation.
- Corolla: 5 Petals, united (gamopetalous), valvate aestivation.
- Androecium: 5 Stamens, epipetalous.
- Gynoecium: Bicarpellary, syncarpous, superior ovary, bilocular, placenta swollen with many ovules.
- Fruit: Berry or capsule.
- Floral Formula: $\oplus$ $\oint$ $K_{(5)}$ $C_{(5)}$ $A_5$ $\underline{G}_{(2)}$
7. Describe the various types of placentations.
- Marginal: Placenta forms a ridge along the ventral suture of the ovary. Ovules borne in two rows (e.g., Pea).
- Axile: Ovules attached to a central axis in a multilocular ovary (e.g., China rose, Tomato, Lemon).
- Parietal: Ovules develop on the inner wall of the ovary or peripheral part. Ovary is one-chambered but becomes two-chambered due to false septum (e.g., Mustard, Argemone).
- Free Central: Ovules are borne on central axis and septa are absent (e.g., Dianthus, Primrose).
- Basal: Placenta develops at the base of the ovary and a single ovule is attached (e.g., Sunflower, Marigold).
Flower Structure & Arrangement
8. What is a flower? Describe the parts of a typical angiosperm flower.
Definition: A flower is a modified shoot wherein the shoot apical meristem changes to floral meristem. It is the reproductive unit in angiosperms.
Parts of a Flower:
- Calyx: Outermost whorl composed of sepals (green, leafy). Protects the flower in bud stage.
- Corolla: Composed of petals (brightly colored). Attracts insects for pollination.
- Androecium: Male reproductive organ composed of stamens. Each stamen has a stalk (filament) and an anther (produces pollen).
- Gynoecium: Female reproductive organ composed of one or more carpels. A carpel consists of stigma (pollen receptor), style (tube), and ovary (contains ovules).
9. Define Inflorescence. Explain the basis for different types.
Definition: The arrangement of flowers on the floral axis is termed as inflorescence.
Basis of Classification: It is based on whether the apex gets converted into a flower or continues to grow.
- Racemose: The main axis continues to grow, and flowers are borne laterally in acropetal succession (younger flowers at the top).
- Cymose: The main axis terminates in a flower, hence limited growth. Flowers are borne in basipetal succession (older flowers at the top).
10. Arrangement of floral members in relation to insertion on thalamus.
Based on the position of calyx, corolla, and androecium in respect of the ovary on the thalamus:
- Hypogynous (Superior Ovary): Gynoecium occupies the highest position while other parts are situated below it. (e.g., Mustard, Brinjal).
- Perigynous (Half-Inferior/Half-Superior): Gynoecium is situated in the center and other parts are on the rim of the thalamus almost at the same level. (e.g., Plum, Rose).
- Epigynous (Inferior Ovary): The margin of thalamus grows upward enclosing the ovary completely and getting fused with it. Other parts arise above the ovary. (e.g., Guava, Cucumber).