Getting to Know Plants Chapter Notes | Eureka Plus Class 6: Book Solutions, Notes & Worksheets PDF Download

Introduction

Plants are living things that are made up of many cells. They are essential for all life on Earth because they produce their own food. Plants play a crucial role in providing food for all living beings, either directly or indirectly. In addition to being a food source, plants also release oxygen into the air, which is vital for all animals to breathe. They offer various benefits such as wood, medicines, and other useful materials. Understanding plants is important for activities like gardening and farming.

Herbs, Shrubs, and Trees

Plants can be categorized into different groups based on their characteristics, such as herbs, shrubs, and trees.

Herbs

• Herbs are small plants characterized by their soft and tender stems, usually consisting of a single main stem. Their roots are shallow and do not penetrate deep into the soil, making them easy to uproot. Due to their shallow root systems, herbs require a consistent and regular supply of water. Most herbs have a short lifespan, typically living for only a few months.
• Examples of herbs include mint, zinnia, aster, lady's finger (okra), spinach, and banana plants. Although banana plants have relatively large stems, their stems are soft, and they have a short lifespan similar to other herbs. Many wild herbs also sprout and thrive during the rainy season.

Shrubs

• Shrubs are medium-sized plants that have multiple thin, woody stems, giving them a bushy appearance. They are larger than herbs but not as tall as trees. The roots of shrubs extend deep into the soil, which makes them difficult to uproot. These deep roots allow shrubs to access water stored deeper underground, reducing the need for frequent watering compared to herbs.
• Common examples of shrubs include pomegranate, jasmine (mogra), and rose plants. Shrubs typically have longer lifespans and can live for several years.

Trees

• Trees are large plants that often grow to significant heights, sometimes exceeding several meters. They possess a tall and broad woody stem known as a trunk, which is usually covered with a hard bark. Trees also have numerous large branches that spread out extensively. 
• Their root systems are extensive and delve deep into the soil, providing strong anchorage and enabling them to absorb water from deep underground sources. This deep root system means that mature trees generally do not require frequent watering.
• The lifespan of trees varies widely; some may live for 40 to 50 years, while others can survive for over a century. Examples of trees include mango, jackfruit, banyan, and teak. An exception to typical trees is the papaya tree, which, despite its height, has a soft stem.

Creepers

• Creepers are plants with weak stems that are unable to stand upright on their own. Instead, they grow along the ground. 
• Most creepers have a short lifespan, living only a few months. Examples of creepers include sweet potato, pumpkin, and melon plants.

Climbers

• Climbers are plants that also have weak and flexible stems but grow by attaching themselves to other plants or structures for support. They have the ability to sense nearby objects and climb onto them. Many climbers possess tendrils, which are specialized structures that help them grasp and climb over supports. Some climbers can live for many years and develop strong, woody stems over time.
• Examples of climbers include various gourd plants such as bitter gourd, bottle gourd, and ridge gourd, as well as the passion flower and morning glory plants.

Parts of a Plant

Most plants consist of two main systems: the root system and the shoot system. The root system typically grows underground, while the shoot system grows above the soil. The shoot system includes the stem, branches, leaves, flowers, and fruits.

The Root System

The roots of a plant primarily perform two essential functions:

• Anchoring the Plant: Roots anchor the plant firmly in the soil, providing stability.
• Absorbing Water and Nutrients: Roots absorb water and minerals from the soil, which are vital for the plant's growth.

Each root is covered in tiny structures called root hairs, which increase the surface area for absorption. The water and dissolved minerals absorbed by the root hairs enter specialized tubes in the roots called xylem tubes. These tubes extend through the stem and reach every part of the plant, ensuring the distribution of water and nutrients.
There are two main types of root systems:

Taproot System

• Description: The taproot system is characterized by a single thick main root with several smaller roots branching off from it.
• Examples: Plants like mango, bean, apple, spinach, turnip, and carrot have taproots.
• Seed Type: Plants with seeds that have two cotyledons (dicots) typically have taproots.

Fibrous Root System

• Description: The fibrous root system lacks a single main root. Instead, it consists of many thin roots that grow from just below the stem.
• Examples: Plants such as turmeric and paddy have fibrous roots. Grasses are also examples of plants with fibrous roots.
• Seed Type: Plants with seeds made up of one cotyledon (monocots) usually have fibrous roots.

Modifications of the Root

Roots can undergo modifications to perform additional functions beyond their usual roles of anchoring the plant and absorbing water and nutrients. These modifications help the plant adapt to its environment or meet specific needs.

Roots Modified to Store Food
In some plants, roots are modified to store food, which helps the plant survive in unfavorable conditions or during dormancy.
Examples of such plants include:

• Carrot
• Beetroot
• Radish

If you observe these plants, you will notice that they have tiny rootlets attached to the main root. These rootlets aid in the absorption of water and nutrients, while the main root stores food.

Roots Modified to Provide Extra Support
Certain plants require additional support to stay upright, especially those that grow tall or spread out. These plants have roots modified specifically for this purpose. Such roots are known as prop roots or aerial roots. They grow from the stem or branches and help stabilize the plant. Examples of plants with prop roots include:

• Maize Plant
• Indian Rubber Plant
• Banyan Tree

Prop roots provide the necessary support to keep these plants steady, especially under challenging environmental conditions.

The Shoot System

The shoot system of a plant primarily consists of the stem, which supports the branches, leaves, flowers, and fruits. The stem plays a crucial role in the growth and development of the plant. Here's how the shoot system functions:

Main Components of the Shoot System

• Stem: The central structure of the shoot system, responsible for bearing branches, leaves, flowers, and fruits.
• Nodes: Points on the stem where leaves are attached.
• Buds: Located at nodes, buds have the potential to grow into branches.

Functions of the Stem

• Support: The stem bears the branches, leaves, flowers, and fruits, holding them in place.
• Water Transport: It carries water absorbed by the roots up to the other parts of the plant.
• Nutrient Distribution: It transports food produced by the leaves to all other parts of the plant.

Water-Conducting and Food-Conducting Tubes—Xylem and Phloem

• Xylem: These are specialized tubes responsible for transporting water absorbed by the roots to the rest of the plant. Xylem ensures that every part of the plant receives the necessary water to function.
• Phloem: These tubes are responsible for carrying food, produced in the leaves through photosynthesis, to all other parts of the plant. Phloem ensures that the energy produced by the leaves is distributed throughout the plant.

The xylem and phloem work together, connecting all parts of the plant and facilitating the movement of essential nutrients and water, ensuring the plant's overall health and growth.

The Bark

The bark is the tough outermost covering of the trunk and older branches of a tree. It serves several important functions:

• Water Loss Prevention: The bark acts as a protective barrier, preventing excessive water loss from the tree.
• Protection: It shields the inner parts of the tree from harsh weather conditions and harmful insects, helping to ensure the tree's survival and health.

In essence, bark plays a crucial role in maintaining the tree's integrity and well-being by offering both physical protection and moisture retention.

Modifications of the stem

Stems Modified to Store Food
Potatoes, turmeric, and ginger plants have stems that can store food underground.
Here's how it works:

• The stems of these plants change to hold food.
• Under the ground, these modified stems grow.
• They have nodes where buds grow during the growing season.
• If you bury a piece of potato, turmeric, or ginger in damp soil, these buds can create new shoots and grow into new plants.

Stems Modified to Store Water and Food
Cactus plants are uniquely adapted to survive in dry deserts. They store water and make food in their stems.
Here's how cacti do this:

• Most cactus plants lack broad leaves.
• Their thick, green stems take on the job of making food for the plant.
• These stems can store water and food, making them thick and fleshy.

Adaptation of Cactus Plants to Dry Environments

• Cactus plants are specially designed to live in dry, sandy deserts.
• Most cactus species do not have wide leaves. Instead, they use their thick, green stems to produce food for themselves.
• The stems of cacti store water and nutrients, making them plump and fleshy.

Stems Modified for Support in Plants like Gourd and Grapevine

• Some plants, such as gourds and grapevines, have stems that can't stand upright on their own.
• These plants develop special structures called tendrils from nodal buds.
• Tendrils are thin, thread-like extensions that coil around nearby objects, helping the plants grow upwards and providing support to their stems.

Leaf

Leaves are like plant solar panels, designed to soak up sunlight efficiently. They are flat, thin, and plentiful, strategically arranged to capture as much sunlight as possible for the plant's growth.

• Leaves are flat and thin because they need sunlight for the plant to grow.
• Each leaf is positioned in a way that ensures it receives an adequate amount of sunlight.

Parts of a Leaf

• Leaf Stalk: The part that connects the leaf to the stem or branch.
• Lamina: The flat, typically green part of the leaf.
• Leaf Veins: Tubes known as xylem and phloem that transport water, nutrients, and sugars throughout the leaf.

Venation

• Reticulate Venation: A branching network pattern of leaf veins, commonly found in dicot plants.
• Parallel Venation: Leaf veins arranged parallel to each other, seen in monocot plants like grass.

Stomata

• Definition: Tiny pores on the leaf surface.
• Function: Allow for the exchange of gases like carbon dioxide and oxygen with the environment.
• Example: Plants take in carbon dioxide through stomata for photosynthesis and release oxygen and water vapor.

Functions of a Leaf
Photosynthesis

• Food Production: Leaves are responsible for making food for the plant. They contain chlorophyll, a green pigment that captures sunlight.
• Process: Through photosynthesis, leaves use sunlight, water, and carbon dioxide to produce food in the form of sugar. This process also releases oxygen into the air through openings called stomata.
• Storage: The food made by the leaves is transported to other parts of the plant by phloem tubes. Excess sugar is converted into starch and stored in various parts of the plant.

Transpiration

• Water Management: Water absorbed by the roots reaches the leaves through xylem tubes. Some of this water is used in photosynthesis, while the rest is released as water vapor through the stomata in a process known as transpiration.
• Regulation: To prevent water loss, many plants close their stomata during periods of water shortage.

Modifications of the Leaf
Leaves can change their shapes and structures for various reasons. Let's explore how leaves can be altered to serve different purposes.

• Leaves modified for food storage: Some leaves can store extra food. For instance, in an onion plant, the part of the leaf above the ground is green, while the part below ground is white and thick. This underground section stores excess food.
• Leaves modified to prevent water loss: Leaves usually lose water through transpiration. Cacti, which grow in dry deserts with little water, have modified their leaves into spines. Spines help cacti save water and protect them from animals.
• Leaves modified to capture insects: Some plants in poor soil eat insects. These insect-eating plants, like the Venus flytrap and the pitcher plant, have leaves that can trap insects. 

Non-Flowering Plants

Plants come in different types, with one way to classify them being into flowering plants and non-flowering plants. Non-flowering plants are those that do not produce flowers. Examples of non-flowering plants include ferns, mosses, and pine trees.
Let's break this down further in simple terms:

• Definition of Non-flowering Plants:
  • Non-flowering plants are plants that do not have flowers.
• Examples of Non-flowering Plants:
  • Ferns: These are green plants that reproduce via spores rather than seeds.
  • Mosses: Small green plants that usually grow in damp or shady locations.
  • Pine Trees: These are tall trees that bear cones instead of flowers.

So, non-flowering plants are a group of plants that do not produce flowers but reproduce through other means like spores or cones. Examples of such plants are ferns, mosses, and pine trees. 

Flowering Plant

Flowering plants are plants that produce flowers, which are essential for their reproduction. These flowers serve as a food source for bees and butterflies, containing nectar that attracts these pollinators. There is diversity in how flowers are structured and arranged on plants.

Key Points

• Definition of Flowering Plants: Plants that have flowers are known as flowering plants.
• Role of Flowers in Plant Reproduction: Flowers are crucial for the reproduction of plants.
• Nectar as Food: Bees and butterflies feed on the nectar found in flowers.
• Varieties of Flower Arrangements:
  • Single Flowers: Some plants produce solitary flowers.
  • Clusters of Flowers: Other plants bear flowers in groups.
  • Many Tiny Flowers: Certain plants have numerous small flowers that collectively form a single, larger flower-like structure.
• Types of Flowers: The flower is connected to the plant through the flower stalk.

Structure of a complete Flower

A complete flower consists of several parts that work together to enable the plant to reproduce. Understanding the structure of a flower is essential to comprehend how plants reproduce and produce fruits and seeds.

• Sepals: Sepals are the outermost leaf-like parts of a flower, typically green in color. They protect the flower while it is a bud and support the petals when the flower blooms.
• Petals: Petals are the colorful parts of the flower that often attract insects. In some flowers, petals have a pleasant scent and play a role in pollination.
• Stamens: Stamens are the male parts of the flower, consisting of the anther where pollen grains are produced. The pollen is essential for fertilization in plants.
• Pistil (Carpel): The pistil is the female part of the flower, located at the center. It comprises the stigma, style, and ovary, which contains ovules that develop into seeds.
• Reproduction: Flowers play a crucial role in plant reproduction. Once fertilization occurs, the ovules develop into seeds, and the flower eventually forms fruits that contain these seeds. When a seed from a ripe fruit finds the right conditions of water, warmth, and air, it can germinate and grow into a new plant.