Modification in Underground Stem

The Practical School

18 Jun 201903:04

Summary

TLDRThis script explores the fascinating world of modified underground stems in plants, which serve various functions beyond just support. It delves into four distinct types: rhizomes, corms, tubers, and bulbs. Rhizomes, like ginger and turmeric, have nodes and internodes with scale leaves. Corms are condensed, less spreading stems with buds, exemplified by the day lily. Tubers, such as potatoes, are spherical and store food with dormant buds called 'eyes'. Bulbs, like onions, are disk-shaped and store food in their fleshy leaves, featuring both scaly and fleshy leaves with a terminal bud.

Takeaways

🌱 The stem provides support and transfers nutrients and water within the plant, as well as food from the leaves to other parts.
🌿 In some plants, stems are modified to perform specific functions, which is the focus of the video.
🌷 Underground stems are a type of stem that grows beneath the soil surface and are adapted for food storage.
🌾 Underground stems are different from above-ground stems in that they swell and become thick, with a definite growth pattern.
🔢 There are four types of underground stems: rhizomes, corms, tubers, and bulbs.
🏵 A rhizome is an underground stem with nodes and internodes, scale leaves, and an irregular shape, with ginger and turmeric as examples.
🌼 A corm is a rounded, underground stem that is condensed and spreads less than a rhizome, with a single bud and an example being the amaryllis.
🥔 A tuber is an enlarged, spherical underground stem with many dormant buds on its surface, known as 'eyes', and potatoes are a common example.
🌻 A bulb is a condensed, disk-like underground stem that stores food in its fleshy leaves, with the onion being a well-known example.
🍃 Bulbs have two types of leaves: fleshy leaves and scaly leaves, with the terminal bud covered by many scaly leaves.
🌱 The terminal bud in bulbs is important for growth and is covered and protected by scaly leaves.

Q & A

What is the primary function of a stem in a plant?
-The primary function of a stem is to provide support to the plant and to transfer nutrients and water from the roots, as well as food from the leaves, to different parts of the plant.
Can stems also perform other roles besides support and nutrient transfer?
-Yes, in some plants, stems can get modified to perform other roles, such as storing food or supporting specialized structures.
What are the characteristics of an underground stem compared to an above-ground stem?
-Underground stems are typically swollen and thick, and they have a definite growth pattern, unlike above-ground stems which tend to grow long.
How many types of underground stems are mentioned in the script?
-The script mentions four types of underground stems: rhizomes, corms, tubers, and bulbs.
What is a rhizome and what are some examples of plants with rhizomes?
-A rhizome is an underground stem with nodes and internodes, covered with scale leaves, and has an irregular shape. It can give rise to new stems and leaves. Examples of plants with rhizomes include ginger and turmeric.
What distinguishes a corm from a rhizome and what is an example of a corm?
-A corm is a condensed form of a rhizome that is round in shape and flat at the top and bottom. It spreads less compared to a rhizome and bears buds in the axils of scale leaves. An example of a corm is the amaryllis.
What is a tuber and how does it differ from other underground stems?
-A tuber is an enlarged, spherical underground stem that stores food and has many dormant buds on its surface, known as eyes. It differs from other underground stems in its spherical shape and the presence of eyes. An example is the potato.
What is a bulb and how does it store food?
-A bulb is a condensed, disk-like underground stem that stores food in its fleshy leaves. It has two types of leaves: fleshy leaves and scaly leaves. The inner fleshy leaves are where the food is stored, as seen in plants like the onion.
What is the role of the terminal bud in a bulb?
-The terminal bud in a bulb is located at the upper part of the stem and is covered by many scaly leaves. It plays a crucial role in the growth and development of the plant.
Can underground stems give rise to new plants?
-Yes, underground stems, such as rhizomes, corms, tubers, and bulbs, can give rise to new plants through the growth of buds present on them.
Why are underground stems important for plants?
-Underground stems are important for plants as they provide support, store food, and in some cases, allow for the propagation of new plants through the growth of buds and the development of new stems and leaves.

Outlines

00:00

🌱 Underground Stem Modifications

This paragraph introduces the concept of underground stem modifications in plants. It explains that while most stems grow above ground, some grow underground to store food. The paragraph outlines four types of underground stems: rhizomes, corms, tubers, and bulbs. Rhizomes are described as underground stems with nodes and internodes, featuring scale leaves and the ability to produce new stems and leaves, with ginger and turmeric as examples. Corms are characterized as round and flat at the top and bottom, bearing buds in the axils of scale leaves, with daughter plants arising from these buds, using the corm as an example. Tubers are enlarged, spherical underground stems with many dormant buds on their surface, known as 'eyes', and can grow into new plants when planted, with the potato as an example. Bulbs are described as condensed, disk-like stems with two types of leaves—fleshy and scaly—with the inner fleshy leaves storing food, and the terminal bud covered by many scaly leaves, using the onion as an example.

Mindmap

Keywords

💡Stem

The stem is the main structural axis of a vascular plant, providing support and facilitating the transport of nutrients and water from the roots to the rest of the plant. In the context of the video, the stem's role is crucial as it discusses the modification of stems, particularly underground stems, which have adapted to store food and support the plant in different ways.

💡Underground Stem

An underground stem is a type of stem that grows beneath the soil surface. It is adapted for storage and support in certain plant species. The video emphasizes the unique characteristics of underground stems, such as their thickened and swollen appearance, and their role in storing food for the plant.

💡Rhizome

A rhizome is a type of underground stem that has nodes and internodes, and is characterized by its irregular shape. It spreads horizontally and can give rise to new stems and leaves. In the script, ginger and turmeric are mentioned as examples of plants with rhizomes, highlighting their role in plant propagation and food storage.

💡Corm

A corm is a short, vertical underground stem that is round in shape and has a condensed form. It is adapted for storing food and is less spreading compared to a rhizome. The script uses the corm as an example, mentioning that it bears buds in the axils of scale leaves from which daughter plants can arise, with 'asparagus' being a given example.

💡Tuber

A tuber is an enlarged, spherical underground stem that serves as a food storage organ. It has many dormant buds on its surface, known as 'eyes,' which can sprout and grow into new plants. The video script provides the example of the potato, illustrating how a tuber can be used to propagate a new plant.

💡Bulb

A bulb is a type of underground stem that is disk-like and stores food in its fleshy leaves. It has a terminal bud covered by many scaly leaves. The inner fleshy leaves are where the food is stored, and the video script uses the onion as an example of a bulb, showing how it is adapted for storage and propagation.

💡Nodes

Nodes are the points on a stem where leaves, buds, or branches are attached. In the context of the video, nodes are important in the structure of underground stems like rhizomes, where they bear scale leaves and can give rise to new growth.

💡Internodes

Internodes are the sections of the stem between two nodes. The video script mentions internodes in the context of rhizomes, indicating that they are part of the structure that allows for the irregular shape and growth pattern of underground stems.

💡Scale Leaves

Scale leaves are modified leaves that are often small and protective, covering the nodes of certain underground stems like rhizomes and tubers. The script explains that these leaves can provide protection and support the growth of new stems and leaves from the buds located in their axils.

💡Buds

Buds are the undeveloped or embryonic shoots and leaves in plants. The video script describes how buds are present in the axils of scale leaves on underground stems like corms and how they can give rise to new plants, such as in the case of the asparagus corm.

💡Food Storage

Food storage in plants refers to the process where excess nutrients are kept for future use, often in specialized structures like underground stems. The video script discusses how modified underground stems, such as tubers and bulbs, serve as organs for storing food, which is essential for the plant's survival and growth.

Highlights

Stem's role in providing support and transferring nutrients and water in plants.

Modification of stems for specific functions in certain plants.

Introduction to the concept of underground stems.

Difference between above-ground and underground stems in growth and structure.

Classification of underground stems into four types.

Description of rhizomes as underground stems with nodes and internodes.

Rhizomes' ability to give rise to new stems and leaves.

Examples of rhizomes: ginger and turmeric.

Definition and characteristics of corm, a type of underground stem.

Corm's condensed form and limited spreading compared to rhizomes.

Corm's bud-bearing axils and daughter plant formation.

Corm example: Asparagus.

Explanation of tubers as enlarged, spherical underground stems for food storage.

Presence of dormant buds, known as eyes, on tubers.

Tuber's capacity for new plant growth from a part with a bud.

Example of a tuber: potato.

Bulb definition and its function as a food-storing, condensed stem.

Differentiation of bulb leaves: fleshy and scaly.

Structure of a bulb with a terminal bud and scaly leaves.

Inner fleshy leaves' role in food storage within a bulb.

Example of a bulb: onion.