7 Most SAQ’s of Taxonomy of Angiosperms Chapter in Inter 1st Year Botany (TS/AP)

4 Marks

SAQ-1 : Describe the non-essential floral parts of plants belonging fabaceae.

Introduction

The Fabaceae family, commonly known as the pea or legume family, includes a wide variety of plants with distinct floral characteristics. Among these characteristics are the non-essential floral parts, which include the calyx and corolla. Understanding these parts is essential to identify and classify plants belonging to the Fabaceae family.

Calyx

1. The calyx is the outermost whorl of the flower and consists of sepals.
2. In Fabaceae, the calyx typically comprises five sepals that are fused together (gamosepalous).
3. The aestivation of the calyx can be either valvate (overlapping but not completely) or imbricate (overlapping fully) in arrangement.
4. The Fabaceae flowers show an asymmetrical arrangement of sepals, with one odd sepal positioned anteriorly, and the remaining sepals are positioned posteriorly.

Corolla

1. The corolla is the second whorl of the flower and comprises petals.
2. In Fabaceae, the corolla consists of five petals, which are separate from each other (polypetalous).
3. The corolla is further specialized into a distinctive arrangement known as the “papilionaceous” corolla.
4. The papilionaceous corolla includes five petals:
   • One large and showy posterior petal, called the “standard”.
   • Two lateral petals, known as “wings,” that flank the standard.
   • Two anterior petals that are fused together, forming a structure called “keels.”
   • The keels enclose and protect the reproductive organs, including the stamens and pistil.

Aestivation

1. The Fabaceae flowers typically exhibit vexillary or descendingly imbricate aestivation.
2. Vexillary aestivation refers to the arrangement where the posterior petal (standard) lies outside and partly covers the lateral wings.
3. Descendingly imbricate aestivation is characterized by the overlapping arrangement of the anterior fused petals (keels) in a descending order.

Summary

The Fabaceae family comprises a diverse group of plants with unique floral characteristics. The non-essential floral parts include the calyx, consisting of five fused sepals, and the corolla, comprising five separate petals in a papilionaceous arrangement. Understanding these non-essential floral parts is vital for the proper identification and classification of plants within the Fabaceae family.

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SAQ-2 : Describe the essential floral parts of plants belonging to liliaceae.

Introduction

Liliaceae is a family of flowering plants that includes various well-known species, such as lilies and tulips. To identify and understand the unique characteristics of plants within the Liliaceae family, it is crucial to be familiar with their essential floral parts, which include the androecium (male reproductive organs) and the gynoecium (female reproductive organ).

Androecium

1. The androecium is the male reproductive whorl of the flower.
2. In Liliaceae, the androecium consists of six stamens, arranged in two whorls, with three stamens in each whorl (3+3 arrangement).
3. The stamens are epiphyllous, meaning they are attached to the tepals (undifferentiated petals and sepals) of the flower.
4. Each stamen comprises a dithecous anther, indicating that it has two thecae or pollen sacs.
5. The anthers are basifixed, attached at their base, and have introrse dehiscence, meaning they open inwards towards the center of the flower.
6. The anthers release pollen through longitudinal dehiscence, where they split lengthwise to disperse the pollen.

Gynoecium

1. The gynoecium is the female reproductive part of the flower.
2. In Liliaceae, the gynoecium is tricarpellary, meaning it consists of three fused carpels.
3. The carpels are syncarpous, indicating that they are fused together to form a single pistil.
4. The ovary is superior, positioned above the attachment point of other floral parts.
5. It is triocular, containing three chambers or locules.
6. The ovules are numerous and attached to the axile placentation, which means they are arranged along the central axis of the ovary.

Style and Stigma

1. The style is the elongated, slender tube-like structure that connects the ovary to the stigma.
2. In Liliaceae, the style is terminal, arising from the top of the ovary.
3. The stigma is trifid, meaning it is divided into three lobes or parts, and it is capitate, appearing as a rounded, knob-like structure.

Summary

The Liliaceae family consists of flowering plants with unique essential floral parts. The androecium includes six stamens arranged in two whorls (3+3), with dithecous anthers that have introrse dehiscence. The gynoecium is tricarpellary, syncarpous, and contains a triocular superior ovary with numerous ovules on axile placentation. The style is terminal, and the stigma is trifid and capitate. Understanding these essential floral parts is essential for the proper identification and classification of plants within the Liliaceae family.

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SAQ-3 : Describe the essential organs of solanaceae.

Introduction

The Solanaceae family, commonly known as the nightshade family, includes important plants like tomatoes, potatoes, and bell peppers. To study and classify these plants accurately, it’s essential to understand their essential organs, including the vegetative and reproductive parts.

Vegetative Organs

1. Roots:
   • The Solanaceae family typically has a taproot system, which may develop into a fibrous root system in some cultivated species.
   • The roots are responsible for water and nutrient absorption from the soil.
2. Stems:
   • Plants in this family possess herbaceous or woody stems.
   • The stems can be either erect or climbing, and they often have hairs (trichomes) that can be glandular or non-glandular.
3. Leaves:
   • The leaves are generally simple and alternate, though compound leaves can also be found in some species.
   • Leaf arrangement is typically alternate, and the leaves usually have a stipule-less base.

Reproductive Organs

1. Flowers:
   • Solanaceae flowers are typically actinomorphic (radially symmetrical) and bisexual.
   • The calyx is persistent and often accrescent, with five sepals either free or fused.
   • The corolla has five petals, usually fused, forming a tube-like structure.
   • The flowers often exhibit a starry or bell-shaped appearance.
2. Androecium:
   • The androecium consists of five stamens, usually adnate to the corolla.
   • The stamens are epipetalous, and their arrangement can be alternate with the petals or opposite to them.
3. Gynoecium:
   • The gynoecium is typically bicarpellary, with the carpels fused to form a bilocular ovary.
   • The ovary is superior, and each locule contains numerous ovules.
   • The style is simple, and the stigma is usually capitate or bilobed.
4. Fruit and Seeds:
   • The fruit is typically a berry or a capsule, with a large number of seeds.
   • Seeds contain a curved embryo surrounded by abundant endosperm.

Summary

Understanding the essential organs of the Solanaceae family is crucial for the accurate identification and classification of these economically and nutritionally important plants. The family is characterized by its vegetative organs (roots, stems, and leaves) and its reproductive organs (flowers, androecium, gynoecium, fruits, and seeds), each playing a vital role in the life cycle of the plants.

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SAQ-4 : Give economic importance of plants belonging to fabaceae.

Introduction

Fabaceae, commonly known as the legume or pea family, is a diverse family of flowering plants that holds significant economic importance due to its various uses and benefits. Let’s explore the economic significance of plants belonging to the Fabaceae family.

1. Pulses:
   • Many leguminous plants are cultivated for their edible seeds, known as pulses.
   • Pulses are an excellent source of proteins and play a vital role in human nutrition.
   • Examples of pulses include Red gram (Toor dal), Black gram, Green gram (Moong dal), and Bengal gram (Chickpeas).
2. Edible Oils:
   • Some members of the Fabaceae family yield edible oils, which are used for cooking and various food preparations.
   • Soybean (Glycine max) and Groundnut (Arachis hypogea) are prominent examples of Fabaceae plants producing edible oils.
3. Vegetables:
   • Several Fabaceae plants provide nutritious and tasty vegetables that are consumed as a part of the diet.
   • Examples include the pods of beans (Dolichos), Soybean (Glycine max), and the leaves of Menthi (Fenugreek).
4. Timber:
   • Certain species within the Fabaceae family are valued for their wood, which is used as timber in construction and furniture making.
   • Red Sanders and Indian Rosewood are notable examples of Fabaceae plants providing valuable timber.
5. Fiber: Fabaceae plants like Sun Hemp (Crotalaria) are a source of fiber, which is used in making ropes, twine, and other textiles.
6. Natural Dyes:
   • Some plants in the Fabaceae family are used to obtain natural dyes.
   • Indigofera tinctoria is known for yielding a blue dye, while Butea monosperma provides a yellow dye.
7. Fodder:
   • Several Fabaceae plants are used as fodder for livestock, as they are rich in nutrients and promote healthy growth in animals.
   • Crotalaria and Phaeceolus are examples of legumes used as fodder.
8. Green Manure:
   • Fabaceae plants are crucial for improving soil fertility through the practice of green manure.
   • Plants like Sesbania and Tephrosia are cultivated as green manure crops to enrich the soil with nitrogen and organic matter.

Summary

The Fabaceae family holds immense economic importance, benefiting various industries and human livelihoods. From being sources of essential proteins, oils, and nutritious vegetables to providing valuable timber, fibers, and natural dyes, these plants play a significant role in agriculture, food production, and economic growth. Additionally, their role as fodder and green manure crops contributes to sustainable agricultural practices and soil enrichment.

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SAQ-5 : Write a brief note on semi technical description of a typical flowering plant.

Introduction

A semi-technical description of a typical flowering plant involves systematically providing information about its various features, starting from its overall appearance and habitat to the detailed structure of its flowers and fruits.

1. Habit and Habitat:
   • Begin the description by stating the plant’s habit, which refers to its general growth form (e.g., herb, shrub, tree).
   • Mention the habitat in which the plant is commonly found, such as forests, grasslands, wetlands, etc.
2. Vegetative Characters:
   • Describe the root system, including whether it is taproot or fibrous, and its function in anchoring and absorbing nutrients.
   • Mention details about the stem, such as its height, branching pattern, and texture (e.g., woody or herbaceous).
   • Discuss the leaf characteristics, including their arrangement (alternate, opposite, whorled), shape, margin, and venation.
3. Floral Characters:
   • Provide information about the type of inflorescence (arrangement of flowers on the main stem), whether it is a raceme, corymb, umbel, etc.
   • Describe the flower’s structure, including the number of floral parts (sepals, petals, stamens, carpels), symmetry (actinomorphic or zygomorphic), and their color and size.
4. Fruits:
   • Mention the type of fruit, whether it is a fleshy fruit like a berry or drupe, or a dry fruit like a capsule or achene.
   • Describe the fruit’s shape, size, color, and any distinctive features.
5. Floral Diagram and Floral Formula:
   • Include a floral diagram, a schematic representation of the flower, showing the number of each floral part and their arrangement.
   • Provide a floral formula, a symbolic representation of the flower’s structure, using abbreviations for each floral part.

Summary

A semi-technical description of a flowering plant covers its habit, habitat, vegetative characters (root, stem, leaves), floral characters (inflorescence, flower, and parts), and fruit. It may also include a floral diagram and floral formula to offer a concise representation of the flower’s structure. This detailed description allows botanists, researchers, and students to understand the plant’s morphology and taxonomy more effectively.

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SAQ-6 : Give an account of floral diagram.

Introduction

A floral diagram is a graphical representation used to describe the structural properties of a flower. This tool is particularly useful in the field of botany for understanding and documenting the arrangement and orientation of the various parts of a flower.

Key Elements of a Floral Diagram

1. Symmetry: Indicates the symmetry of the flower, whether it’s actinomorphic (radial symmetry) or zygomorphic (bilateral symmetry).
2. Position of Floral Organs: Depicts the spatial arrangement of the flower’s organs – the sepals, petals, stamens, and carpels.
3. Ovary Position: Shows the position of the ovary in relation to other floral parts, distinguishing between superior, inferior, and half-inferior ovaries.
4. Fusion of Floral Parts: Illustrates the fusion of different floral parts, if any, such as united petals forming a corolla tube.

Drawing a Floral Diagram

1. Start by representing the flower’s axis at the center of the diagram.
2. Add concentric circles to represent different whorls of the flower.
3. Sepals are usually depicted in the outermost circle, followed by petals, stamens, and carpels in the center.
4. Use symbols or letters to represent different parts (e.g., ‘S’ for sepals, ‘P’ for petals).
5. Indicate the ovary’s position and whether it is superior, inferior, or half-inferior.

Significance

1. A floral diagram provides a simplified yet comprehensive view of a flower’s structure.
2. It’s especially helpful in comparing flowers from different species or families.
3. The diagram aids in the identification and classification of plants.

Summary

A floral diagram is a crucial tool in botany, offering a simplified graphical representation of a flower’s structure. It outlines the symmetry, position of floral organs, ovary position, and fusion of floral parts. Drawing a floral diagram involves depicting the flower’s axis, whorls, and individual floral parts with appropriate symbols. Its significance lies in its ability to provide a clear and concise view of a flower’s architecture, aiding in the study and comparison of various plant species.

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SAQ-7 : Write a brief account on the class of dicotyledonae of Bentham and Hooker’s classification.

Introduction

The class Dicotyledonae, as per Bentham and Hooker’s classification system, is one of the major groups in the plant kingdom. This class is characterized by plants having two cotyledons in their seeds and encompasses a wide range of species.

Key Characteristics of Dicotyledonae

1. Cotyledons: The most defining feature of Dicotyledonae is the presence of two cotyledons (seed leaves) in the embryo.
2. Leaf Venation: The leaves generally show reticulate venation, where veins form a network.
3. Floral Structure: Flowers are mostly tetramerous or pentamerous (having four or five parts).
4. Root System: These plants typically have a taproot system.
5. Vascular Bundles: In the stem, the vascular bundles are arranged in a ring.

Subdivisions in Dicotyledonae: Bentham and Hooker divided Dicotyledonae into three subclasses:

1. Polypetalae: Characterized by flowers with free petals.
2. Gamopetalae: In these plants, the petals are united.
3. Monochlamydeae: These plants have inconspicuous or no petals.
4. Polypetalae: Further divided into Thalamiflorae, Disciflorae, and Calyciflorae based on the arrangement of the floral parts.
5. Gamopetalae: This subclass is characterized by flowers with fused petals and is divided into Inferae, Heteromerae, and Bicarpellatae based on ovary position and the number of carpels.
6. Monochlamydeae:
   • Consists of plants with either no petals or where the petals and sepals are not distinctly differentiated.
   • This group is often considered more primitive in the Dicotyledonae.
7. Economic Importance: Dicotyledonae includes many economically important plants providing fruits, vegetables, wood, and medicinal substances.

Summary

In Bentham and Hooker’s classification, the class Dicotyledonae is distinguished by two cotyledons, reticulate leaf venation, tetramerous or pentamerous flowers, a taproot system, and vascular bundles in a ring. It is subdivided into Polypetalae, Gamopetalae, and Monochlamydeae, with further divisions based on floral characteristics. This class includes a vast array of plants with significant economic and ecological importance.