Plant Anatomy and Morphology

Dr. Denise DeBusk
30 Dec 201916:07

Summary

TLDRThis script offers an insightful exploration into plant anatomy and morphology, focusing on the structural and functional aspects of various plant components. It delves into the life cycle phases of plants, from growth to senescence, and highlights the roles of roots, stems, leaves, flowers, and fruits. The video educates viewers on the differences between monocots and dicots, and the importance of understanding these distinctions for plant classification and utilization.

Takeaways

  • 🌿 Plant morphology focuses on the physical form and external structure of plants, while plant anatomy delves into their internal structure.
  • 🍅 The tomato plant serves as an example, highlighting its taproot system, compound leaves, and the fact that its flower parts are in multiples of 5s, with a fleshy berry fruit.
  • 📈 The plant life cycle has three phases: the initial growth phase, the juvenile phase with exponential size increase and specific traits, and the mature phase where the plant can reproduce.
  • 🍃 Leaves are the primary site for photosynthesis, converting carbon dioxide and water into carbohydrates and oxygen, with light and chlorophyll being essential.
  • 🌱 The structure of leaves can vary greatly, with simple and compound leaves, different venation patterns, and various margins and bases.
  • 🌳 Stems support the plant, transport nutrients, and can also store food; they have various parts including terminal and axillary buds, nodes, and internodes.
  • 🌾 Monocots and dicots differ in their stem anatomy, with monocots having scattered vascular bundles and dicots having them in a ring.
  • 🌱 Roots are crucial for water and nutrient absorption, and can also store food and provide anchorage; they can be taproot or fibrous systems.
  • 🌸 Flowers are the reproductive parts of plants, attracting pollinators and producing fruits and seeds, with structures like sepals, petals, stamens, and pistils.
  • 🍉 Fruits are mature ovaries that can be fleshy or dry, and include a variety of forms like tomatoes and sunflowers, which are botanically fruits.
  • 🌱 Seed germination involves overcoming dormancy, water uptake, and the breakdown of food reserves, leading to the emergence of the radicle and seedling growth.

Q & A

  • What is the difference between plant morphology and plant anatomy?

    -Plant morphology describes the physical form and external structure of plants, while plant anatomy focuses on the study of the internal structure of plants.

  • What are the main parts of a tomato plant as described in the script?

    -The main parts of a tomato plant are roots, stems, leaves, flowers, and fruits. The root is a taproot system, the leaves are compound with alternate attachment, the flower parts are in multiples of 5s, and the fruit is a fleshy berry.

  • What are the three phases of a plant's life cycle mentioned in the script?

    -The three phases of a plant's life cycle are the initial growth phase, the juvenile phase, and the reproductive or mature phase. Each phase has distinct characteristics related to growth, development, and reproductive potential.

  • How does the juvenile phase of a plant differ from the mature phase?

    -In the juvenile phase, plants exhibit exponential growth and are unable to shift from vegetative to reproductive maturity. They have specific morphological and physiological traits. In contrast, the mature phase is characterized by qualitative changes that allow the plant to express its full reproductive potential.

  • What is the primary function of leaves in a plant?

    -The primary function of leaves is to manufacture food for the plant through photosynthesis, which involves the conversion of carbon dioxide and water into carbohydrates and oxygen in the presence of light.

  • What are the basic parts of a simple dicot leaf?

    -The basic parts of a simple dicot leaf include the petiole (leaf stem), the blade (flat part of the leaf), the midrib (largest vein), and veins (for transporting water and nutrients). Other features include the leaf margin, leaf apex, leaf base, and stipule.

  • How do the venation patterns in leaves differ between monocots and dicots?

    -Monocots have only parallel venation, while dicots have reticulate (net-like) venation patterns. This difference can be used to help identify the type of plant.

  • What are the main functions of stems in plants?

    -Stems are used to support leaves, flowers, and fruits. They contain transport systems for water and minerals (xylem) and manufactured food (phloem). Stems can also manufacture food to a lesser extent than leaves and act as storage organs for food.

  • What are the key anatomical features found in stems?

    -Key anatomical features in stems include the epidermis, cortex, cambium, xylem, phloem, and pith. These structures are involved in protection, support, cell formation, and the transport and storage of water, nutrients, and food.

  • What is the main function of roots in plants?

    -The main function of roots is to absorb water and nutrients to sustain plant life. Roots also act as storage organs for carbohydrates and provide anchorage and support for the plant.

  • How do flowers contribute to plant reproduction?

    -Flowers are the reproductive parts of plants. They attract pollinators and undergo pollination and fertilization to produce fruits and seeds, which are essential for plant reproduction and dispersal.

  • What is the botanical definition of a fruit, and how does it differ from a vegetable?

    -Botanically, a fruit is a mature ovary of a flowering plant, which can be fleshy or dry and contains seeds. A vegetable, on the other hand, comes from the roots, stems, leaves, or flowers of plants. For example, a tomato is technically a fruit because it develops from the ovary, but in common usage, it may be considered a vegetable.

  • What are the criteria for seed germination to occur?

    -For seed germination to occur, the seed must be viable, exposed to appropriate environmental conditions, and any primary dormancy must be overcome. The process involves water uptake (imbibition), enzyme activation for storage reserve breakdown, and the emergence of the radicle followed by seedling growth.

  • What are the main differences between monocots and dicots?

    -Monocots have one cotyledon, parallel leaf veins, scattered vascular bundles in the stem, a fibrous root system, and flower parts in multiples of three. Dicots have two cotyledons, netlike or reticulate leaf veins, vascular bundles usually arranged in a ring, a taproot system, and flower parts in multiples of four or five.

Outlines

00:00

🌿 Plant Anatomy and Morphology Overview

This paragraph introduces the fundamental concepts of plant morphology, which describes the physical form and external structures of plants, and plant anatomy, focusing on their internal structures. Dr. DeBusk uses a tomato plant as an example to illustrate various plant parts and their characteristics. The paragraph also delves into the plant life cycle, detailing the phases of growth, including the juvenile phase with its unique traits and the mature phase, which enables full reproductive potential. Senescence, the final phase involving natural deterioration, is also discussed, along with its associated changes.

05:06

🍃 Leaf Structure and Function in Plants

This section explores the primary vegetative structures of plants, emphasizing the role of leaves in photosynthesis and transpiration. It describes the parts of a simple dicot leaf, including the petiole, blade, midrib, veins, and various leaf margins and bases. The paragraph also explains different venation patterns and the concept of modified leaves, which can resemble other plant structures. The discussion on leaves includes their attachment patterns to the stem and the importance of recognizing simple and compound leaves for plant identification.

10:09

🌱 Stem and Root Systems of Plants

The focus of this paragraph is on the stem and root systems, highlighting their functions in support, transport, and storage. Stems are described in terms of their basic parts, such as terminal and axillary buds, nodes, and internodal regions, as well as their internal anatomy, including the epidermis, cortex, cambium, xylem, phloem, and pith. Modified stems for storage and reproduction are also mentioned. Roots are discussed in the context of their role in water and nutrient absorption, anchorage, and storage, with an explanation of the primary root, secondary roots, and root hairs. The paragraph concludes with a look at the two major classes of root systems: taproot and fibrous.

15:12

🌺 Reproductive Structures and Seed Germination

This paragraph discusses the reproductive aspects of plants, starting with the structure and function of flowers, which serve to attract pollinators and produce fruits and seeds. It explains the parts of a typical flower, including sepals, petals, stamens, and pistils, and differentiates between complete, incomplete, perfect, and imperfect flowers. The formation of fruits after pollination and fertilization is described, with a distinction between fleshy and dry fruits. The paragraph also covers the germination process of seeds, detailing the criteria for germination and the stages involved, including imbibition, enzyme activity, and the emergence of the radicle and seedling growth.

🌼 Monocots vs. Dicots: Key Differences

The final paragraph provides a summary of the differences between monocots and dicots, two major groups of flowering plants. It outlines the characteristics of monocots, such as having one cotyledon, parallel leaf veins, scattered vascular bundles, a fibrous root system, and flower parts in multiples of three. In contrast, dicots are characterized by two cotyledons, netlike leaf veins, ring-arranged vascular bundles, a taproot system, and flower parts in multiples of four or five. The paragraph concludes by emphasizing the importance of understanding plant anatomy and life cycles for classification and utilizing plants to their full potential.

Mindmap

Keywords

💡Plant Morphology

Plant Morphology refers to the description of the physical form and external structure of plants. It is a fundamental aspect of botany that helps in identifying and classifying plants based on their observable characteristics. In the video, Dr. DeBusk uses the tomato plant as an example to illustrate the concept, highlighting its roots, stems, leaves, flowers, and fruits, which are all part of the plant's morphology.

💡Plant Anatomy

Plant Anatomy is the study of the internal structure of plants. It delves into the cellular and tissue organization within plant bodies, which is crucial for understanding their growth and function. The script mentions that by looking deeper into the tomato plant, one can observe features like the taproot system and compound leaves, which are part of the plant's anatomy.

💡Taproot System

A taproot system is a type of root system where a main root, or taproot, grows vertically downward with smaller lateral roots branching off from it. This system is common in dicotyledonous plants, as exemplified by the tomato plant in the script, where the root structure is described as a taproot system.

💡Compound Leaves

Compound leaves are leaves that are made up of multiple separate leaflets, each of which is attached to a central axis or rachis. In the script, the tomato plant's leaves are described as compound with an alternate attachment to the stem, indicating a key characteristic of the plant's morphology.

💡Life Cycle

The life cycle of a plant refers to the series of stages a plant goes through from its initial growth to senescence and eventual death. The script outlines three phases: the juvenile phase, the reproductive or mature phase, and the senescence phase, each with distinct characteristics and functions that are essential to the plant's development and reproduction.

💡Apical Meristem

The apical meristem is the primary growing point of the stem, responsible for the upward growth of the plant. It is a region of actively dividing cells that contribute to the increase in plant height. The script mentions that during the initial growth phase, the apical meristem does not typically respond to conditions that initiate flowering.

💡Photosynthesis

Photosynthesis is the process by which plants convert carbon dioxide and water into carbohydrates and oxygen using light energy. It is a vital function of leaves, as described in the script, where both light and chlorophyll are necessary for this process to occur. Photosynthesis is central to the plant's ability to produce food and release oxygen into the atmosphere.

💡Transpiration

Transpiration is the process of water loss from the plant to the atmosphere in the form of water vapor, primarily occurring through the stomata on the leaf surface. The script explains that transpiration is an important function of the leaf, which, along with photosynthesis and respiration, contributes to the overall health and growth of the plant.

💡Leaf Venation

Leaf venation refers to the pattern of veins in a leaf, which are responsible for the transport of water and nutrients throughout the leaf. The script describes different venation patterns such as parallel, pinnate, and palmate, with monocot plants typically having only parallel venation, which is a key characteristic for identifying plant types.

💡Modified Leaves

Modified leaves are leaves that have changed from their typical form to serve a specialized function. The script provides examples such as bracts, which are leaves located just below the flower and tendrils, which are appendages produced by certain vines for climbing. Modified leaves are an important concept as they can be mistaken for other structures and are crucial for understanding plant adaptation and diversity.

💡Fruit

A fruit, as defined in the script, is the mature ovary of a flowering plant that results from pollination and fertilization. The video distinguishes between two types of fruits: fleshy fruits, like the tomato, which have soft fleshy material, and dry fruits, like a sunflower, which have a hard fruit wall. The script also addresses the common misconception about the tomato being a vegetable, clarifying its botanical classification as a fruit.

Highlights

Plant morphology describes the physical form and external structure of plants, while plant anatomy studies their internal structure.

The tomato plant is composed of roots, stems, leaves, flowers, and fruits, with specific characteristics like taproot system and compound leaves.

Plant life cycle includes three phases: initial growth, reproductive maturity, and senescence, each with distinct characteristics.

Juvenile plants exhibit traits like exponential growth and inability to form flowers, with examples like ivy and Eastern red cedar.

Leaves are the primary structures for photosynthesis, converting carbon dioxide and water into carbohydrates and oxygen.

Stomata are tiny pores on leaves that allow gas exchange necessary for photosynthesis and respiration.

Leaves have basic parts like petiole, blade, midrib, and veins, which help in identification and function.

Leaf venation patterns can be parallel, pinnate, or palmate, with monocots typically having only parallel venation.

Stems support leaves, flowers, and fruits, and contain transport systems for water, minerals, and manufactured food.

Stem anatomy includes the epidermis, cortex, cambium, xylem, phloem, and pith, each with specific functions.

Roots absorb water and nutrients, provide anchorage, and can also serve as storage organs for carbohydrates.

Root systems are classified as taproot or fibrous, with examples like carrots and grasses respectively.

Flowers are the reproductive parts of plants, attracting pollinators and producing fruits and seeds.

A typical flower consists of sepals, petals, stamens, and pistils, with variations in complete, incomplete, perfect, and imperfect flowers.

Fruits are mature ovaries of flowering plants, coming in two types: fleshy and dry, with examples like tomatoes and sunflowers.

Seeds are mature fertilized eggs contained in fruits, with methods of dispersal and storage of food varying between monocots and dicots.

Seed germination involves water uptake, enzyme activity, and food reserve breakdown, leading to radicle emergence and seedling growth.

Differences between monocots and dicots include the number of cotyledons, leaf vein patterns, root systems, and flower part multiples.

Knowledge of plant anatomy and life cycle is crucial for plant classification and maximizing their potential uses.

Transcripts

play00:00

Plant morphology is the description of the physical form and external structure of plants

play00:05

while plant anatomy is the study of the internal structure of plants. Look at this tomato plant, it is made up of

play00:13

roots, stems, leaves, flowers, and fruits. If you dig in deeper, you notice that the

play00:17

root is a taproot system, that the leaves are compound leaves in a alternate attachment

play00:22

to the stem, the flower parts are in multiples of 5s, and the fruit is a fleshy berry. I’m

play00:28

Dr. DeBusk and in this video, you will dive into the terms for plant anatomy and morphology,

play00:33

so that you may understand plants more and be able to classify them. You also learn what

play00:39

I meant when I described that tomato plant. The plant’s life cycle has three phases

play00:44

with varying characteristics. In the initial period of growth, the apical meristem, which

play00:49

is the primary growing point of the stem, will not typically respond to internal or

play00:53

external conditions to initiate flowers. The juvenile phase of development exhibits exponential

play00:59

increases in size and the inability to shift from vegetative to reproductive maturity leading

play01:05

to the formation of flowers. In addition, juvenile plants have specific morphological

play01:10

and physiological traits. Hedera helix, or ivy, in the immature stage has five lobes,

play01:17

whereas in the mature stage it has none. The ivy commonly seen around campuses is mostly

play01:23

immature; it is actually fairly hard to find plants in the mature stage. Young growth in

play01:29

Juniperus virginiana, Eastern red cedar, has thorns, whereas older growth does not. Examples

play01:36

of physiological traits during the juvenile stage include vigorous plant growth, disease

play01:41

resistance, and a greater ability to regenerate roots and shoots. The reproductive or mature

play01:47

phase refers to qualitative changes that allow the plant or organ to express its full reproductive

play01:54

potential. Both genetic and environmental conditions determine when plants enter this

play01:58

phase. Senescence phase involves internally controlled deteriorative changes, which are

play02:05

natural causes of death. Changes that occur during senescence include the following: decreases

play02:11

in chlorophyll, protein, DNA and RNA, and photosynthesis; and changes in plant hormones

play02:17

– some increase while some decrease. When the senescence phase is complete, leaf abscission

play02:23

occurs. The leaves, stems, and roots make up the primary

play02:28

vegetative structures of the plant. They take part in growth processes that are essential

play02:32

to the plant’s survival. The main function of a leaf is to manufacture food for the plant

play02:37

during photosynthesis. Photosynthesis refers to a series of chemical reactions in which

play02:41

carbon dioxide and water are converted in the presence of light to carbohydrates (sugar)

play02:47

and oxygen. Both light and chlorophyll are essential to photosynthesis. Carbon dioxide

play02:54

and other gases enter and exit the leaf through tiny pores in the leaf’s surface called

play02:59

stomata. Another important function carried out by the leaf is transpiration, which is

play03:03

the loss of water from the leaf in the form of water vapor. Respiration is another important

play03:09

function carried out by the leaf; this process uses sugars made during photosynthesis and

play03:14

breaks them down into simpler molecules (such as water and carbon dioxide) that are used

play03:19

as energy for plant growth and development. Leaves consist of several basic parts that

play03:25

help identify them. The major parts of a simple dicot leaf are listed here. If you start at

play03:30

the stem, the leaf stem or stalk that attaches the leaf is the petiole. The blade is the

play03:37

flat thin part of the leaf. The midrib is the largest vein located in the middle of

play03:42

the leaf. Veins are used to transport water and nutrients throughout the plant. The different

play03:47

leaf venation patterns found in plants can be parallel, pinnate, palmate. Monocot plants

play03:54

have only parallel venation. The leaf margin is the outer edge of the leaf blade, which

play04:00

can be lobed, smooth, toothed, or various combinations of the three. The leaf apex is

play04:06

the tip of the leaf blade, which can be pointed, rounded, or a variety of other shapes. The

play04:11

leaf base is the bottom of the leaf blade, which can be rounded, pointed, or a variety

play04:17

of other shapes. A stipule is a small leaflike appendage to a leaf, typically borne in pairs

play04:23

at the base of the leaf stalk. Various leaf coverings include hairy versus not hairy,

play04:29

waxy versus not waxy, and others. The simple leaf consists of one blade per

play04:35

petiole, such as found on an oak leaf. The compound leaf has two or more leaflets, such

play04:42

as found on a potato leaf. The main difference between a leaf and a leaflet is the position

play04:47

of the axillary bud, which is located at the base of the entire leaf; leaflets do not have

play04:54

axillary buds. Differences in how leaves are attached to stems are commonly used as a means

play04:59

of plant identification. Leaves are attached to stems in three major patterns. The opposite

play05:05

pattern occurs when two leaves are directly across from each other, or two leaves per

play05:11

node. The alternate pattern occurs when leaves are staggered along the length of the stem,

play05:16

or one leaf per node. The whorled pattern occurs when three or more leaves are attached

play05:22

per node. Modified leaves are commonly mistaken for

play05:26

other structures such as flowers or stems. To illustrate this point, these are some examples

play05:31

of modified leaves. Bracts are leaves located just below the flower, for example, the poinsettia

play05:37

and dogwood. Tendrils are appendages produced by certain vines that wrap around a support

play05:44

and allow them to climb, for example, the grape.

play05:49

Stems can be used to identify plants with some practice. The stem has several important

play05:53

functions. Stems are used to support leaves, flowers, and fruits. Stems contain important

play05:58

transport systems, including the xylem for transporting water and minerals, and the phloem

play06:04

for transporting manufactured food. Stems can be used to manufacture food, but to a

play06:09

lesser extent than the leaves. Stems can act as a storage organ for food; an example of

play06:14

this is the Irish potato. The basic parts of the stem are described

play06:20

here. The terminal bud is positioned at the tip of the stem and contains an undeveloped

play06:25

leaf, stem, flower, or mixture of them all. The bud scale is a tiny leaf-like structure

play06:31

that covers the bud and protects it. The terminal bud-scale scar is left when the terminal bud

play06:37

begins growth in the spring; it represents one year’s growth. The axillary bud is located

play06:43

along the side of the stem below the terminal bud. The node is the point along the length

play06:49

of the stem where leaves or stems are attached. The internodal region is located between the

play06:56

nodes. The leaf scar is left when the leaf drops. The lenticels are tiny pores located

play07:03

in the stem and are used for gas exchange; an example of a tree with conspicuous lenticels

play07:10

is the cherry tree. Within the stem, the water, nutrients, and

play07:15

food made during photosynthesis are transported throughout the plant and stored for later

play07:21

use. The internal anatomies of a monocot (has one cotyledon and parallel leaf venation)

play07:27

and dicot stem (has two cotyledons and reticulate leaf venation) are shown on the slide. A key

play07:33

feature is that monocots have vascular bundles that are scattered and dicots have vascular

play07:39

bundles in a ring. The following are key anatomical features found in stems. The outer layer of

play07:46

plant parts is the epidermis, just like our skin is our epidermis. The primary tissue

play07:53

of the stem or root is the cortex, which is located between the epidermis and vascular

play07:59

region. Think of this as the filler tissue. The cambium is the area where new plant cells

play08:05

are formed – either xylem or phloem during secondary growth. When grafting, the cambium

play08:11

layers must match for the graft union to be successful. The cambium is only found only

play08:18

in woody plants. The xylem is composed of tiny tubes that transport water and nutrients

play08:24

up from the roots to other parts of the plant. The annual rings in a tree are made up of

play08:29

xylem. The phloem is composed of tiny tubes that transport manufactured food and carbohydrates

play08:36

from the leaves down to other parts of the plant, such as the roots and shoots. The pith

play08:41

is located in the center portion of the stem where food and moisture are stored.

play08:47

In addition to standard stems, there are also modified stems used for storage of reserves

play08:52

and for reproduction. An aboveground horizontal stem with long and thin internodes is a stolon,

play08:58

such as in strawberry runners. A belowground horizontal stem is a rhizomes, such as ginger

play09:05

root or turmeric. A tuber is an underground rounded swelling of a stem such as Irish potatoes.

play09:13

Corms are vertical, thick stems with thin, papery leaves, like gladiolus. Bulbs are short

play09:19

shoots with thick, fleshy leaves like onions and tulips.

play09:24

The major function of the root is to absorb water and nutrients to sustain plant life.

play09:29

In addition, roots act as storage organs for carbohydrates and provide anchor and support

play09:35

for the top portion of the plant. The first structure to emerge from a germinating seed

play09:40

is the root. The key parts of the root are described here. The primary root is the main

play09:45

root that first emerges from the seed. Starting from the tip of the primary roots, there is

play09:51

a the root cap, just behind the root cap is the area of cell division, followed by the

play09:56

area of cell elongation, and then the area of maturation or cell differentiation. The

play10:03

secondary root arises from the primary root. Root hairs are single cells that absorb the

play10:08

greatest amount of water and minerals. Improper handling during transplanting can cause the

play10:13

loss of many root hairs, which decreases the plant’s water uptake and results in transplant

play10:19

shock. The root cap is located at the tip of the root and consists of several layers

play10:24

of cells that protect the root as it grows through the soil.

play10:26

There are two major classes of root systems. The taproot system has a primary root that

play10:32

grows down from the stem with only a few secondary roots; both carrots and dandelions are examples.

play10:38

This is common for dicots. The fibrous root system has a large number of small primary

play10:43

and secondary roots; potato plants and grasses are examples. This root system is common for

play10:49

monocots. Modified roots serve as a reserve food-storage system; an example of a modified

play10:54

root is a sweet potato. Be careful not to confuse the modified-root sweet potato with

play11:00

the modified-stem Irish potato. The reproductive parts of the plant are the

play11:06

flowers, which are pollinated and fertilized to produce the fruits. The main function of

play11:10

flowers is to attract pollinators and to produce fruit and seed. Flowers come in a variety

play11:15

of sizes, shapes, and colors to achieve their main function. In addition to their main function,

play11:20

flowers are commonly used for plant identification and produced commercially for their beauty

play11:24

and fragrance. A typical flower consists of four major parts. The sepals are green, leaf-like

play11:30

structures located beneath the petals. The calyx is the term used to describe all the

play11:35

sepals on one flower. The calyx is used for protection. For example, some plants have

play11:41

calyx that contain spines, which deter animals from feeding on them. The petals are the brightly

play11:47

colored portions of the flower that are used to attract pollinators. The stamens are the

play11:52

male reproductive part of the flower. The stamen consists of a filament that supports

play11:57

the anther, which produces the male sex cells (pollen). The pistils are the female reproductive

play12:03

part of the flower. The pistil consists of the stigma, which is the sticky surface for

play12:08

collecting pollen; the style, which is the tube that connects the stigma and ovary; and

play12:13

the ovary, which contains ovules or eggs. Monocots typically have flower parts in multiples

play12:18

of 3 while dicots have their flower parts in multiples of 4s and 5s.

play12:24

Flowers can be broken down into four different classes. The complete flower contains all

play12:28

four major flower parts: sepals, petals, stamens, and pistils. The incomplete flower lacks one

play12:35

or more of the major flower parts. In the photo of the American elm, the sepals and

play12:39

petals are lacking. Since these plants are pollinated through wind, this allows the wind

play12:44

to pick up the pollen easier and for it to blow onto the pistil. The perfect flower contains

play12:50

both stamens and pistils. The imperfect flower lacks either stamens or pistils; an example

play12:56

of a plant containing this type of flower is corn.

play13:00

Fruits are formed after the flower has been pollinated and fertilized. The definition

play13:04

of a fruit is a mature ovary of a flowering plant. There are two types of fruits. The

play13:09

fleshy fruit, such as a tomato, has soft fleshy material with or without seeds enclosed. The

play13:14

dry fruit, such as a sunflower, has seeds enclosed in a hard fruit wall. Isn’t it

play13:19

wild that something like beans or corn is considered a fruit? From the botanical definition,

play13:24

a fruit simply comes from the ovary of a plant while a vegetable comes from the roots, stems,

play13:29

leaves, or flowers of a plants like cauliflower or lettuce. By this definition, a tomato is

play13:35

mostly definitely, a fruit. The informal definition of a fruit is something that is sweet.

play13:40

A seed is the mature fertilized egg that is contained in the fruit. Seeds can be dispersed

play13:48

by the wind like dandelions, stuck to the fur of animals, or spread in other ways. Dicots

play13:54

store their reserved food in cotyledons, whereas monocots store their food in the endosperm.

play13:59

The germination process is a series of events whereby the seed embryo goes from a dormant

play14:04

state to an actively growing state. For seed germination to occur, the following criteria

play14:09

must be met. The seed must be viable, which means that the embryo is alive and capable

play14:14

of germination. The seed must be exposed to appropriate environmental conditions. Primary

play14:20

dormancy must be overcome in the seed. Three stages of seedling germination are as

play14:27

follows. First is imbibition of water which is the active uptake of water by the seed.

play14:34

After the seed is hydrated, preexisting enzymes are immediately available for breaking down

play14:39

storage reserves, and new enzymes are produced for the breakdown of additional reserves.

play14:44

Lastly, preexisting and newly formed enzymes break down food reserves, which are used for

play14:49

the germination process. The first visible sign of seed germination and growth is the

play14:54

emergence of the radicle followed by growth of the seedling. The following are two common

play14:58

forms of seed germination. Epigeous seed germination where the hypocotyl elongates and brings the

play15:05

cotyledons above ground like in cherries. Hypogeous seed germination where the epicotyl

play15:12

emerges and the cotyledons remain below the soil surface, such as in corn.

play15:18

You heard various differences between monocots and dicots. You should be able to identify

play15:23

these differences. Here is a summary. Monocots have one cotyledon, leaf veins that are parallel,

play15:29

vascular bundles in their stem are scattered, fibrous root system, and flower parts in multiples

play15:35

of three. Dicots have two cotyledons, veins that are netlike or reticulate, vascular bundles

play15:42

are usually arranged in a ring, a taproot system, and flower parts in multiples of four

play15:46

or five. In conclusion, knowledge of basic plant anatomy, including vegetative (leaves,

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stems, and roots) and reproductive (flowers and fruits) plant parts, together with understanding

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the plant’s life cycle is important in plant classification, as well as in maximizing the

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plant’s potential uses.

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Etiquetas Relacionadas
Plant AnatomyMorphologyBotanyPlant ClassificationVegetative StructuresReproductive PartsSeed GerminationFruit TypesRoot SystemsLeaf VariationGrowth Cycles
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