Learning objective

• Plant structure of the main parts of a typical flowering plant

• Describe the function of roots and stem • Label the parts of a flower on a

diagram, and describe the functions of each part

• What is the difference between pollination and fertilization?

The Shoot System is

found

ground and the Root System

is found

ground.

ABOVE

BELOW or UNDER

Plant Body Organization A plant consists of: 1. Root system, which is underground -Anchors the plant, is used to absorb water

and minerals, conduction and storage 2. Shoot system, which is above ground -Consists of supporting stems,

photosynthetic leaves and reproductive flowers

Each has an apex that extends growth

Both systems depend on the other.

– Lacking chloroplasts and living in the dark,

roots would starve without the sugar and other organic nutrients imported from the photosynthetic tissues of the shoot system.

– Conversely, the shoot system (and its reproductive tissues, flowers) depends on water and minerals absorbed from the soil by the roots.

MAIN ROOT

LATERAL OR SIDE

ROOT ROOT

SYSTEM

LEAF STEM

FLOWER

FRUIT

NODE

NODE

NODE

INTER- NODE

TERMINAL BUD AXILLARY BUD

SHOOT SYSTEM

The Root Structure of root Types of Root Systems Functions of the Root System

Structure of root

Roots have several structures, such as root caps and root hairs that stems lack.

Root cap

• Each root tip is covered by a root cap.

• The function of the root cap is to cover and protect the delicate growing tip from injury and damage as the root pushes its way through the soil.

Root hairs

• Root hairs are tiny projections and outgrowths on the outermost layer of the root epidermis.

• The root hairs increase absorption of water and minerals near the root tip.

Looks like a tangled mass of roots

Examples of plants With this root system are Rice Corn Sugar Cane

Fibrous root • A fibrous root system - to many roots

of the same size developing from the end of the stem, with smaller lateral roots branching off these roots.

• Fibrous root systems, which are located relatively close to the surface of the soil, are adapted to obtain rainwater from a larger area as it drains into the soil.

• Monocots most often have fibrous roots.

Have a large main central root

Have many branching roots

Go deep in the soil

Examples of plants : Large trees e.g. mango, avocado Shrubs e.g. tomato, peppers

• A taproot system - one main root with many smaller lateral roots. Lateral roots often initially occur in regular rows along the length of the main root.

• Taproot systems often extend down into the soil to obtain water located deep underground

Roots : - anchor plants firmly in the ground - absorb water and minerals from the soil

- Storage - some plants, can store starch

- of some plants can be used to grow a new plant

Question

• Name the two organ systems and three basic organs found in all plants.

• What are root hairs and what is the function of root hairs?

• Briefly explain the fibrous root. • Describe the functions of roots.

Summary • The root system is generally underground

and obtains water and dissolved nutrient minerals for the plant.

• Root also anchor the plant firmly in place. • A tap root system has one main root from

which many smaller lateral roots extend. • A fibrous root system has several to many

oots of the same size developing from the end of the stem.

The shoot system above – ground portion

The shoot system consists of stems, leaves, flowers and fruits that contain

seeds. And the growth occurs at

apex. Some stems grow

underground – Bulbs and rhizomes etc. They may be swollen to store food

e.g. potatoes.

Woody Plant Stem The stems support the leaves and flowers. In the case of a tree, the stems are the trunk and all the branches, including the smallest twigs.

External stem structure • Stems all have buds,

which are undeveloped embryonic shoots.

• A terminal bud (apical) is the embryonic shoot located at the tip of a stem.

• Axillary buds, also called lateral buds, are located in the axils of a plant’s leaves.

External stem structure • When terminal and

Axillary buds grow, they form stems that bear leaves and/or flowers.

• The area on a stem where each leaf is attached is called a node, and the region between two successive nodes is an internode.

External Stem Structure

• Terminal bud = Extends the shoot system during the growing season

• Axillary bud = Develops into branches with leaves or may form flowers

• Node = Point of attachment of leaf to stem

• Internode = Area of stem between two nodes

Functions of plant stems • Support

• Conduction

• Production

• Annual –complete their life cycle in a single year or less (grains, legumes)

• Biennials - (such as carrot, cabbage) take two years to complete their life cycles before dying. In the first season they produce extra carbohydrates, which they store and use during their second year when they typically form flowers and reproduce.

• Perennials – plants that live and reproduce for more than two years. They include trees, shrubs, but herbs can also be perennial.

Leaves

External Anatomy Leaf Types Function

Leaves

Leaves may be round, needle-like, scale like, heart-shaped, fan-shaped, or thin and narrow. They vary in size, colour, texture.

Tendrils

Mayapple

EXTERNAL ANATOMY • Leaves possess a blade or lamina, an edge

called the margin of the leaf, the veins (vascular bundles), a petiole, and two appendages at the base of the petiole called the stipules.

margin

Structure

The petiole, which joins the leaf to a stem node.

Some leaf blades are attached directly to the stem and lack a petiole or stipules. These are termed sessile leaves.

Structure • In the absence of

petioles in grasses and many other monocots, the base of the leaf forms a sheath that envelops the stem. Some monocots, including palm trees, do have petioles.

Structure • The arrangement of

veins, differ in monocots and dicots.

• Most monocots have parallel major veins that run the length of the blade, while dicot leaves have a multi-branched network of major veins.

veins

Structure: Leaf Types

Structure: Leaf Arrangement

Function of leaves

• Photosynthesis • Transpiration - 99% of water absorbed

by plant is lost by transpiration • Exchange of gases –

oxygen and carbon dioxide

What is the difference between deciduous and evergreen?

• Deciduous - they shed all their leaves at

the same time and produce new leaves the following rainy season.

• Evergreen - shed their leaves over a long time period, so that some leaves are always present.

Summary • The shoot system is generally aerial and

obtains sunlight and exchanges gases such as carbon dioxide and oxygen – The shoot system consists of a vertical stem

that bears leaves (the main organs of photosynthesis) and reproductive structures (in flowering plants, flowers and fruits).

– Buds (undeveloped embryonic shoots) develop on stems.

Summary • Buds are undeveloped embryonic shoots. A

terminal bud is located at the tip of a stem, whereas axillary buds (lateral buds) are located in leaf axils.

• The area on a stem where each leaf is attached is called a node, and the region of a stem between two successive nodes is an internode.

Summary • Leaves exhibit variation in shape and form. • Leaves typically consist of a broad, flat blade and a stalk-like petiole. Some leaves also possess small, leaf like outgrowths from the base called stipules.

• Leaves may be simple or compound • Leaf arrangement on a stem may be alternate, opposite or whorled

• Leaves may have parallel or netted (either pinnately netted or palmately netted) venation.

Summary • Monocot and dicot leaves can be

distinguished based on their external structure.

• Monocot leaves have parallel venation, whereas dicot leaves have netted venation.

• The main function of stems is support, conduction and production of new living tissues.

Basic Flower Structure

The Parts of a Flower

Most flowers have four parts: • sepals, • petals, • stamens, • Pistil or carpel.

Complete flowers

• Complete flowers usually have four parts-sepals, petals, stamens and pistil-which are usually borne on a receptacle.

Incomplete flower

• Incomplete flowers lack one or more of the four part: sepals, petals, stamens, or pistil.

The parts of a flower • Sepals protect the

bud until it opens. • Petals attract

insects. • Stamens make

pollen. • Carpels grow into

fruits which contain the seeds.

Parts of the Flower • Sepals

– Outer covering of the flower bud.

– Protects the stamens and pistils when flower is in bud stage.

– Collectively known as the calyx.

Parts of the Flower • Petals

– Brightly colored – Protects stamen & pistils. – Attracts pollinating

insects. – Collectively called the corolla.

– Collectively sepals (calyx) and petals (corolla) are called the perianth.

Parts of the Flower (Stamen) • Male reproductive part

– Anther • Produces pollen

– Filament • Supports the anther

– Collectively or a group of stamens is the androecium.

Pistil (female)

• Stigma • Style • Carpel (ovary)

• Ovules (eggs)

Collectively or a group of pistil or carpel is known as Gynoecium

Parts of the Flower (Pistil) • Female reproductive part

– Ovary • Enlarged portion at base of pistil • Produces ovules which develop

into seeds – Stigma

• Holds the pollen grains

- Style • Connects the stigma with the ovary. • Where pollen tube grows down to

female sex cells. • Supports the stigma so that it can

be pollinated.

Ovules (eggs)

• The stamens and pistils are considered the essential parts of the complete flower for sexual reproduction.

• The sepal (calyx) and the petals (corolla) are accessory flower parts.

• A flower with both stamen and pistil (carpel) are considered as perfect flower.

• Imperfect flower has either one but not both.

Petals Stigma

Anther Filament

Ovary

Sepals

Ovules Nectaries

Style

Collect a cut-out flower, colour it in and put it together.

Carpelfemale parts

Stamen male parts

What do the parts do?

Sepals- protect the flower when it is a bud

Petals- colourful to attract the insects

Nectaries- give out sugary liquid to attract insects

Stamen- anther produces male sex cells (pollen)

stigma traps pollen

Style is where pollen tube grows down to female sex cells.

ovary produces female sex cells (ovules)

Flowers

• Function – Contain the sexual

organs for the plant. – Produces fruit, which

protects, nourishes and carries seeds.

– Attracts insects for pollination.

Learn About Plants - Different Parts.flv

Quick Test 1. Name the parts of a flower that

attract insects. 2. Name the male part of a flower. 3. Which part of the flower contains

ovules? 4. Which part of the flower produces

pollen? 5. Which part of a flower catches

pollen grains?

Label the parts of a flower

SUMMARY •A flower may contain sepals, petals, stamens, and carpel (pistils). •Sepals cover and protect the flower parts when the flower is a bud. •Petals play an important role in attracting animal pollinators to the flower. •Stamens produce pollen grains. •Each pistil has three sections: a stigma, on which the pollen grains land; a style, through which the pollen tube grows; and an ovary that contains one or more ovules.

Pollination and Fertilisation

Pollination

• Pollination involves the transfer of pollen (male gamete) from the anther to the stigma (outermost female part)

• Plants are pollinated by insects

or the wind.

Pollination

Self-pollination • Pollen from the

anther is transferred to the stigma in the same flower or a different flower on the same plant

Cross Pollination

• Pollen from the anther of one plant is transferred to the stigma of a different plant of the same species

Learn About Plants - Life Cycle.flv

1. Insect-pollinated flowers may have:

• Brightly coloured petals- blue or

yellow petals.

• Strong sweet fragrance

• Nectar producing glands

• Guidelines to lead insects to Nectar

• Stamen are inside

• Stigma and pollen are sticky

Mode of Pollination

2. Wind-pollinated flowers may have:

• Large stigmas outside the flower

• Little or no fragrance

• Light non-sticky pollen

• Lack showy petals

Insect Pollinated Plants

Wind Pollinated Plants

Wind/Insect Pollination

Mode of Pollination (Continued)

5. Water-pollinated flowers may have:

• Pollen which floats on water

(this form of pollination is rare)

4. Mammal-pollinated flowers may have:

• White flowers

• Strong fruity odour

• Flowers opening at night

3. Bird-pollinated flowers may have:

• Long tube shaped flowers

• Bright red and yellow flowers

• No odour

http://www.gesneriads.ca/paliav08.htm

Feature Reason

small petals, often brown or dull green

no need to attract insects

no scent no need to attract insects

no nectar no need to attract insects

pollen produced in great quantities

because most does not reach another flower

pollen very light and smooth so it can be blown in the wind

anthers loosely attached and dangle out

to release pollen into the wind

stigma hangs outside the flower

to catch the drifting pollen

stigma feathery or net like to catch the drifting pollen

Wind Pollinated Flowers

Feature Reason

large, brightly coloured petals to attract insects

often sweetly scented to attract insects

usually contain nectar to attract insects

moderate quantity of pollen less wastage than with wind pollination

pollen often sticky or spiky to stick to insects

anthers firm and inside flower to brush against insects

stigma inside the flower so that the insect brushes against it

stigma has sticky coating pollen sticks to it

Insect Pollinated Flowers

Pollination Summary

Structure Wind Pollinated

Insect Pollinated

Petals

Pollen

Stamen

Stigma

nectar

dull

light

dangling

feathery

none

bright colour

sticky

inside flower

sticky

makes sugar

Fertilisation

• Fertilisation involves the fusion of the nucleus of the male gamete (in the pollen) with the nucleus of the female gamete (in the ovules).

Fertilisation • Pollen grains

germinate on the stigma, growing down the style to reach an ovule.

• Fertilised ovules develop into seeds.

• The ovary enlarges to form the flesh of the fruit and to protect the ovary.

*The ovule forms the seed and the ovary forms the fruit.

• A fruit is a ripened ovary

Pollination of flowers.flv

Seed dispersal Seeds are dispersed in many different ways: • Wind • Explosion • Water • Animals • Birds • Scatter

Seeds must be carried away (dispersed / scattered) from the parent plant to:

• Reduce overcrowding

Seed Dispersal- why?

• Reduce competition for:

- Water

- Light

- Nutrients

What is a benefit of a seed being dispersed far away from

parent plant? • This helps to raise the offsprings

chance of survival, at the same time ensuring the parent plants survival.

• If the seeds land close to the parent plant competition for resources such as water, sunlight, and nutrients will take place, weakening both the offspring plants as well as the parent plant.

How birds and animals help seed dispersal

• Some seeds are

hidden in the ground as a winter store.

• Some fruits have hooks on them and cling to fur or clothes.

How birds and animals help seed dispersal

• Birds and animals

eat the fruits and excrete the seeds away from the parent plant.

Seed Dispersal

Dispersal method

Description Seeds/ Fruits

Wind Seeds are designed to travel as far as possible. May have extensions which act as parachutes or wings. Fruits may be shaken like a pepper pot.

Learn About Plants - Seed Dispersal.flv

Quick Test-A

1. What term is used to describe male and female gametes?

2. What is pollination? 3. Name the two types of pollination. 4. Describe the differences in the pollen

between insect and wind pollinated plants.

5. Explain why the stigmas of wind pollinated flowers hang outside the flowers.

Quick test-B 1. Why do wind pollinated flowers not

produce nectar? 2. How does the male gamete reach the

female gamete? 3. What is a fruit? 4. Name three ways in which fruits and

seeds are dispersed. 5. Why is it important that fruits and

seeds are carried away from the parent plant?

Parts Of A Flowering Plant.flv

Summary • Pollination is the transfer of pollen grains from

anther to stigma. • Flowers pollinated by insects are often yellow or

blue and possess a scent. • Bird-pollinated flowers are often yellow, orange

or red and do not have a strong scent. • Bat-pollinated flowers often have dusky white

petals and possess a scent. • Plants pollinated by wind often have smaller petals

or lack petals altogether and do not produce a scent or nectar; wind-pollinated flowers make copious amounts of pollen.

Summary

• Fertilised ovules develop into seeds. • Seeds are enclosed within fruits,

which are mature, ripened ovaries. • Seeds and fruits are adapted for

various means of dispersal, including animals, wind, water and explosive dehiscence.