Morphology of Flowering Plants Class 11 Notes: CBSE Biology Chapter 5

Morphology involves the study of structure, size, colour, form, etc. of various components of an organism. Like you have read it in your previous classes, parts of a plant can be classified into two sections – the root and shoot system.

Roots: First, the topics of the root systems are covered. The classifications like taproots, fibrous roots and adventitious roots are elaborated. Next, the different root regions are discussed in Chapter 5 Class 11 Biology Notes:

• Root cap.

• Place where the meristematic activity takes place.

• Elongation region.

• Maturation region.

• Root hairs.

Furthermore, the roots of a few plants change their structure and shape to offer other functions. Some examples are storage, respiratory, prop, adventitious, stilt, climbing, foliar and haustorial roots.

Regions of the Root 

The root tip is protected by a thimble-like root cap as it pushes through the soil. Just above the root cap is the region of meristematic activity, where small, thin-walled cells with dense protoplasm divide rapidly. Above this, in the region of elongation, cells grow in length. Further up, in the region of maturation, these cells differentiate and form root hairs, which absorb water and minerals from the soil.

Stem: In this section of Class 11 Biology Notes Chapter 5, you will get to know about the different parts of the shoot system starting with the stem, nodes, internodes, etc. Further, the various modifications of stem-like sub-aerial modification (runner, stolon, sucker and offset), underground modification (tuber, rhizome, corm and bulb), and aerial modification (phylloclade and thorns) are discussed.

Leaf: Biology Class 11 Chapter 5 Notes PDF covers all the details related to leaves as per the CBSE curriculum. Starting from the diagram, leaf parts (leaf base, petiole and lamina), leaf types, lifespan of a leaf to lamina venations, students can stay assured to find every essential detail. Plus, the modification of leaves is also discussed explicitly.

Venation 

Venation refers to the pattern of veins and veinlets in a leaf's lamina. When veinlets form a network, it is called reticulate venation, typically found in dicot plants. In parallel venation, veins run parallel to each other, commonly seen in monocot plants.

Types of Leaves

A leaf is called simple when its lamina is whole or has incisions that don’t reach the midrib. If the incisions reach the midrib, dividing the leaf into leaflets, it’s considered compound. Both simple and compound leaves have a bud at the petiole's axil, but leaflets of compound leaves do not have buds. Compound leaves are of two types: pinnately compound, where leaflets are arranged along a central rachis, like in neem, and palmately compound, where leaflets are attached at a single point, like in silk cotton.

Phyllotaxy

Phyllotaxy is the arrangement of leaves on a stem, with three types: alternate, opposite, and whorled. In alternate phyllotaxy, one leaf per node alternates along the stem, as seen in the china rose. Opposite phyllotaxy has two leaves per node directly across from each other, like in guava. Whorled phyllotaxy features more than two leaves per node forming a circle, such as in Alstonia.

Inflorescence: This section of Class 11 Biology Chapter 5 Notes cover the definition of inflorescence along with its types like racemose and cymose. These two classifications are further segregated into various types mentioned below:

• Racemose – Raceme, spike, catkin, spadix, corymb, capitulum and umbel.

• Cymose – Uniparous cyme (helicoid cyme and scorpioid cyme), dichasial or biparous cyme and multiparous cyme.

In the last portion of the leaf segment of class 11 Bio Ch 5 notes, special kinds of inflorescence like cyathium, hypanthodium and verticillaster are provided.

Flower: Ch 5 Bio Class 11 Notes PDF’s flower section introduces you to the various significant details about the flower and its comprising parts – stamen, petal, sepal and carpel, flower symmetry, floral leaf insertion, bract types, etc. Plus, you will also get to study about the different parts of a flower-like corolla and calyx and its various forms. Moreover, information about the types of aestivation in corolla is explored like valvate, twisted, imbricate and vexillary.

Detailed explanations on stamen cohesions (monadelphous, diadelphous, synandrous, syngenesious and polyadelphous), stamen adhesions, their length, ovule cohesion, placentation, etc., have also been provided.

Parts of a Flower

Each flower normally has four floral whorls, viz., calyx, corolla, androecium and gynoecium.

Floral Whorls

A typical flower has four main floral whorls: calyx, corolla, androecium, and gynoecium.

Calyx

The calyx is the outermost whorl, composed of sepals, usually green and leaf-like, protecting the flower in the bud stage. Sepals can be united (gamosepalous) or free (polysepalous).

Corolla

Corolla consists of petals, often brightly colored to attract insects for pollination. Petals may be united (gamopetalous) or free (polypetalous). Aestivation refers to the arrangement of petals or sepals in a bud, with types like valvate, twisted, imbricate, and vexillary.

Androecium

The androecium is made up of stamens, the male reproductive organs. Each stamen has a filament and an anther, which produces pollen. Stamens may be attached to petals (epipetalous) or the perianth (epiphyllous). They can be free (polyandrous) or united in bundles (monadelphous, diadelphous, polyadelphous).

Gynoecium

The gynoecium is the female reproductive part, consisting of one or more carpels, each with a stigma, style, and ovary. Carpels may be free (apocarpous) or fused (syncarpous). After fertilisation, ovules develop into seeds, and the ovary becomes the fruit. Placentation is the arrangement of ovules in the ovary, with types such as marginal, axile, parietal, basal, and free central.

Fruit and Seed: Like the previous parts of a plant, the fruit and seed section also covers all details associated with the same. Like for instance, you will get accustomed to what is meant by epicarp, endocarp, mesocarp, true and false fruit, fruit classifications, etc. On the other hand, the seed section covers the structure of a dicot and monocot seed.

Besides, some other topics like the semi-technical description of a flowering plant, vegetative character, floral characters, and essential flowering plant families and their economic importance, etc. are also elaborated.

Structure of A Dicotyledonous Seed

The outer covering of a seed is called the seed coat, which has two layers: the outer testa and inner tegmen. The hilum is a scar on the seed coat where the seed was attached to the fruit, with a small pore above it called the micropyle. Inside the seed coat is the embryo, consisting of an embryonal axis and two cotyledons, which store food. At the ends of the embryonal axis are the radicle and plumule. Some seeds, like castor, contain endosperm for food storage (endospermic seeds), while others like bean and pea lack endosperm when mature (non-endospermic seeds).

Structure of Monocotyledonous Seed

Monocotyledonous seeds are usually endospermic, though some, like orchids, are non-endospermic. In cereals such as maize, the seed coat is thin and fused with the fruit wall. The endosperm, which stores food, is separated from the embryo by a protein-rich aleurone layer. The small embryo is located in a groove at one end of the endosperm and has a single large cotyledon called the scutellum. The plumule and radicle are covered by protective sheaths known as the coleoptile and coleorhiza, respectively.

Semi-Technical Description of A Typical Flowering Plant

A flowering plant is described starting with its habit, roots, stem, and leaves, followed by the floral parts. The floral formula uses symbols: Br for bracteate, K for calyx, C for corolla, P for perianth, A for androecium, and G for gynoecium. Symbols also indicate ovary type, sex, and flower symmetry (⊕ for actinomorphic and for zygomorphic). Fusion is shown with brackets, and adhesion by lines. The floral diagram shows the arrangement of flower parts, with a dot indicating the mother axis, as seen in mustard (Brassicaceae family).

Solanaceae

The potato family is a large group found in tropical, subtropical, and temperate regions.

Vegetative Characters:

The plants are mostly herbs, shrubs, and occasionally small trees. The stem is usually herbaceous, sometimes woody, and can be erect, cylindrical, branched, solid or hollow, and hairy or smooth. In potato (Solanum tuberosum), the stem is underground. Leaves are alternate, simple, or rarely pinnately compound, without stipules, and have reticulate venation.

Morphology of Flowering Plants Basic Subjective Questions - Class 11 Revision Notes

Section–A (1 Mark Questions)

1. In mangroves, pneumatophores are the modified adventitious roots. How are these roots helpful to the plant?

Ans. Pneumatophores in mangroves help the plant to get oxygen for respiration.

2. State the main function of leaf tendril.?

Ans. In some plants, the leaves get converted to tendrils which help the plant for climbing, e.g., pea.

3. Why are mustard flowers referred to as hypogynous.?

Ans. The flowers of mustard are called hypogynous because the ovary is situated at the top and the other three whorls are inserted below it.

4. Name two plants where seeds do not have endosperm?

Ans. The plants that do not have an endosperm are beans, gram and pea.

5. What is the name given to the cotyledon in the case of monocots?

Ans. The monocots consist of one large and shield-shaped cotyledon known as the scutellum.

Section–B (2 Mark Questions)

6. What type of aestivation in corolla is found in the pea flower? Explain.

Ans. In peas, a vexillary type of aestivation is present in the corolla. In this type, there are five petals. The largest one (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel). This type of aestivation is also called papilionaceous. 

7. What is venation in leaves? What are the types of venation?

Ans. Vention- It is the arrangement of veins and the veinlets in the lamina of a leaf. There are mainly two types of venations:-

• Parallel venation: In this, the veins run parallel to each other within a lamina, e.g., monocotyledons.

• Reticulate venation:  In this, the veinlets form a network, e.g., dicotyledons.

8. Provide the scientific terms for the following. 

(i) Swollen leaf base in leguminous plants.

(ii) The flat and expanded portion of a leaf. 

(iii) Orderly arrangement of leaves on the stem or branch. 

(iv) Lateral appendages on either side of the lea

Ans. 

(i) Pulvinus

(ii) Lamina/ leaf blade

(iii) Phyllotaxy 

(v) Stipules

9. What do you mean by inflorescence? Explain different types of it.

Ans. Inflorescence- It is the arrangement of flowers on the floral axis. It is divided into two types based on whether the apex gets converted into a flower or continues to grow.

(i) Racemose inflorescence- In this, the main axis continues to grow, the flowers are borne laterally in acropetal succession. 

(ii) Cymose inflorescence- In this, the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order.

10. Distinguish between prop root and stilt roots.

Ans. 

Prop roots- these roots arise from horizontal aerial branches of a tree. They provide support to the plant, e.g., the banyan tree.

Stilt roots- these roots arise from lower nodes of the stem. These roots provide support to the stem, e.g., maize, sugarcane.

11. (a) What are the three parts of an ovary?

(b) Define apocarpous ovary and syncarpous ovary. 

Ans. 

(a) The ovary is divided into three parts: stigma, style, and ovary.

(b) Apocarpous ovary- When more than one carpel is present, they may be free and called apocarpous, e.g., lotus and rose.

Syncarpous ovary- In such ovaries, carpels are fused, e.g., mustard and tomato.

5 Important Topics of Class 11 Chapter 5 You Shouldn’t Miss!

Importance of Morphology of Flowering Plants Class 11 Notes

• Provides detailed knowledge of plant structures, helping students comprehend how different parts of a plant contribute to its overall function and survival.

• Explains various modifications in plant morphology that help plants adapt to different environments and conditions, which is crucial for understanding plant diversity.

• Offers insights into plant structures and functions that are essential for improving crop management and agricultural techniques.

• Serves as a foundational chapter for more advanced topics in botany and plant sciences, facilitating a deeper understanding of plant biology.

• Helps students consolidate their understanding of key concepts related to plant morphology, which is important for performing well in exams and assessments.

Tips for Learning the Class 11 Biology Chapter 5 Morphology of Flowering Plants

• Break the chapter into sections like roots, stems, leaves, flowers, and fruits, and study each part separately.

• Use and create diagrams to understand plant structures and their functions better.

• Make flashcards with key terms and functions for quick review and self-testing.

• Relate textbook concepts to real plants by observing and identifying them in nature.

• Write summaries of each section in your own words to reinforce understanding.

• Discuss the material with classmates and explain concepts to others to enhance your grasp of the topics.

Conclusion

The Morphology of Flowering Plants Class 11 Notes make understanding key concepts like plant parts, their functions, and how they adapt much simpler. By breaking down complicated ideas into easy-to-follow points and using helpful diagrams, these notes help you learn and remember important details more easily. Reviewing these notes regularly will build your confidence and improve your exam performance. With a good understanding of plant morphology, you’ll be ready for any questions on this topic.

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