vascular plants with seeds-angiosperms

8/22/2019 Vascular Plants With Seeds-Angiosperms

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Angiosperms- RS- 1- 2012/13 1

SHES1202 BIOLOGY OF ORGANISMS

Angiosperms

From water to land

PLANTLEAF

performs

photosynthesis

CUTICLE

reduces water

loss; STOMATA

allow gas exchange

STEMsupports plant

(and may perform

photosynthesis)

Surrounding water

supports the alga

ALGA

WHOLE ALGA

performs

photosynthesis;

absorbs water,

CO2, andminerals from

the water

HOLDFASTanchors the alga

ROOTS

anchor plant;

absorb water and

minerals from

the soil (aidedby mycorrhizal

fungi)

Angiosperms:

Flowering plants

Vascular seed plants

Angeion = vessel ; Sperma = seed

Seed within a vessel or enclosed seed.

Produced the reproductive structures:

flowers

fruits

Seed develops from an ovule within a carpel.

Part of an ovary will becomes a fruit


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Gymnosperm vs. Angiosperm

Seeds

Gymno-sperm: naked seed

Angio-sperm: little case seed

ovule

ovule

shoot tip

(terminal bud)lateral

(axillary)bud

young leaf

flower

EPIDERMIS

leaf

seeds(inside

fruit)250

witheredcotyledon

root hairs

root tip

root cap

node

node

internode

VASCULAR TISSUES

GROUND TISSUES

SHOOT SYSTEM

ROOT SYSTEM

primary root

lateral root

The flower

Flower an angiosperm structures specialized for reproduction.

Specialized shoot with four basic parts:

1. Sepals/calyx usually green; protect the flower bud.

2. Petals/corolla brightly colored; to attract pollinators


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3. Stamen male reproductive organ

collectively called androceium

4. Carpel female reproductive organ

collectively called gynoecium

Structure of one type of flowerStructure of one type of flower

petal

(of corolla)

attract pollinators

sepal

(of calyx)

protect the

flower bud

produce

microspores

produce

megaspores

pollen is

produce

receives

pollen

develop into seeds

after fertilizationpedicel

receptacle

petal + sepal = perianth

An ovule containing a mature female gametophyte. TheAn ovule containing a mature female gametophyte. The

gametophyte is a sevengametophyte is a seven--celled structure. One cell (the "endospermcelled structure. One cell (the "endosperm

mother cell") has two nuclei and will help form the endosperm, amother cell") has two nuclei and will help form the endosperm, a

nutritive tissue for the forthcoming embryo. Another cell is thenutritive tissue for the forthcoming embryo. Another cell is the egg.egg.


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The leaves

Fig. 35.23b(TE Art)

CopyrightThe McGraw-Hill Companies,Inc. Permission required forreproduction ordisplay.

Terminalbud

Petiole

Stipules

BladeNode

Axillary bud

Terminalbud scalescars

Internode

Fig. 35.34(TE Art)

Copyright TheMcGraw-Hill Companies,Inc.Permission required forreproduction ordisplay.

Upperepidermis

Palisademesophyll

SpongymesophyllLowerepidermis

Cuticle

Guard cell Stoma VeinGuard cell Stoma

Vein

Internal structure of leaves

In classifying angiosperms:

Taxonomists may use leaf morphology as a criterion

Petiole

(a) Simple leaf

A simple leaf is a single,

undivided blade.

Some simple leaves are

deeply lobed, as in an

oak leaf.

(b) Compound leaf

In a compound leaf, the

blade consists of

multiple leaflets.Notice that a leaflet

has no axillary bud

at its base.

(c) Doubly compound leaf

In a doubly compound

leaf, each leaflet is

divided into smaller

leaflets.

Axillary bud

Leaflet

Petiole

Axillary bud

Axillary bud

LeafletPetiole


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Some plant species:

Have evolved modified leaves that serve various functions.

(a) Tendrils.

The tendrils by which this

pea plant clings to a support are

modified leaves.

After it has lassoed

a support, a tendril forms a coil that

brings the plant closer to the support.

Tendrils are typically modified leaves,

but some tendrils are modified stems,

as in grapevines.

(b) Spines.

The spines of cacti, such as this prickly

pear, are actually leaves, and

photosynthesis is carried out mainly by the

fleshy green stems.

tendrils

(c) Storage

leaves.

Most succulents,

such as this ice

plant,

have leaves

modified for

storing water

(d) Bracts.

Red parts of the poinsettia

are often mistaken for petals but areactually modified leaves called bracts

that surround a group of flowers.

Such brightly colored leaves attract

pollinators.

(e) Reproductive leaves.

The leaves of some

succulents, such as

Kalanchoe daigremontiana,

produce

adventitious plantlets,

which fall off the

leaf and take root in the

soil.

adventitious

plantlets


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Cactus spines are modified leaves that protect the fleshy

stem from consumption by animals. The leaf of the pitcher

plant is modified to collect water. When an insect falls into

the water it becomes trapped. The insect is then digested

providing the plant with organic nitrogen.

The roots

TYPES OF ROOTSTYPES OF ROOTS

A taproot system A fibrous root system


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Many

plants

have

modified

roots

(a) Propagative

roots(b) Storage roots (c) Strangling aerial

roots

(d) Buttress roots (e) Pneumatophores

Classification of angiosperms

All angiosperms are placed in single phylum

Magnoliophyta

Magnoliopsida

(Dicots)

Liliopsida

(Monocots)


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In seeds, two

cotyledons

(part of the

embryo)

Usually four or

five floral parts

(or multiples

of these)

Usually a

netlike arrayof leaf veins

Basically,three pores

of furrows in

pollen grain

vascular

bundle Vascular

bundles

arrayed

as a ringin stem

DICOTSMONOCOTS

In seedsonly onecotyledon

Usually threefloral parts(or multiples

of three)

Usually a

parallel arrayof leaf veins

Basically, one

pore or furrowin pollen grain

Vascular

bundles

distributedground tissue

of stem

ComparisonComparison

of the mainof the main

features thatfeatures that

distinguishdistinguish

dicotsdicots fromfrom

monocotsmonocots

The pollen

Develop from microspores.

Outer layer exine.

Exine contains chemical that may later react with other chemical in the stigma of

a flower. As a result of these reactions, the pollen grain may germinate or further

developmental may be blocked depending on whether or not it originated from the

same plant or other plant of same species or different species.

Many pollen grains have pore-like thin areas in the wall.

The fruits

A mature ovary.

Found only in angiosperms.

Protects the seeds by enlarging the ovary wall.

Aids in dispersal of seeds.


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Pollination triggers hormonal changes:

cause the ovary to grow

Wall of the ovary becomes pericarp

As the ovary grows, the other parts of the flower wither away.

If the flowers not pollinated:

fruits are not develop

entire flowers withers and fall away.

Various modifications in fruit help disperse seeds:

1. Seeds within fruits that function like a kites

enhance dispersal by wind.

eg: Dandelion and Maple

2. Some plants have fruits modified as burrs that cling to animal fur or human

clothes.

3. Some produce edible fruits that is nutritious, sweet-tasting and commonly vividly

colored.

fruits are dispersed by animals/human in a mutualistic system.

4. Some seeds can move modest distances by explosive means

eg: when the pods of garbanzo beans rapidly split.

5. Some fruits, such as coconut, are dispersed by water.


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Fruits are classified into several types depending on

their developmental origin

Simple fruit Aggregate fruit Multiple fruit

A fruit derived from

single ovary.

Fleshy cherry

Dry soybean pod

A fruit derived from

single flower that has

several carpels.

Eg: blackberry

A fruit develops from

an inflorescence (a

group of flowers tightly

clustered together).

Eg: pineapple


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Sexual

reproduction

Stamen male reproductive parts:

Anther contains pollen.

Filament stem-like portion of the stamen that holds the anther erect.

Carpel female reproductive parts of the flower:

Stigma sticky end part of the carpel for pollen attachment.

Style the stalk that raises the stigma out of the flower.

Ovary area in which the ovules are kept. Ovary wall will develop into

fruit.


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Pollination

Pollination:

transfer of pollen to the stigma of the flower.

Pollination may occur through the actions of:

pollinators or

by the wind.

Types of pollinators differ in the:

morphology of their feeding structures

their nutritional requirements.

The morphology, color, odor, and reward (nectar and/orpollen) of flowers have evolved

to attract a particular type of pollinator.

Bee-pollinated flowers are sweet and fragrant.


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Flowers pollinated by beetles tend to have stronger, spicy and fruity odor. Beetles

dont have keen visual sense and flower pollinated by them are usually white and

dull in color.

Some flowers smell like rotten meat and flowers tend to be dull or brown and

pollinated by short-tongue flies.

Night-flying moths pollinated white or yellow flowers colors that stand out

against dark background in moonlight.

Birds dont have sense of smell, but they have excellent vision. So they visit

flower that is bright red or yellow and have little odor.

Fertilization

Fertilization:

o referred to as double fertilization because

o each of the two sperm cells in a pollen grain

o fuses with a haploid cell in the ovule.

When a pollen grain lands on a stigma:

it germinates

forming a pollen tube that grows down the style.

Upon entering the ovule, one of the sperm cells fuses with the egg to

form a zygote.

The other sperm cell fuses with the two polar nuclei forming a triploid

cell that divides to produce endosperm:

the tissue that surrounds and nourishes the

developing embryo.


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HAPLOID

DIPLOID

Egg (n)

Ovule

Stigma

Pollengrain

Pollentube

Sperm

Fertilization

Seedcoat

Embryo(2n)

Seeds

Sporophyte

Ovary

Ovule

Pollen (n)

Meiosis

1 Haploid sporesin anthers develop

into pollen grains:male gametophytes.

2 Haploid spore in eachovule develops intofemale gametophyte,which produces egg.

3 Pollinationandgrowthof pollentube

4 Zygote(2n)

5 Seed

6 Fruit

7 Seedgerminates,

and embryogrows into plant.

Food supply

Within the ovule, the developmental process begins with the :

enlargement of the endosperm, which is the source of nutrition for the embryo.

The cells of the embryo then divide forming a shoot end and a root end.


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The shoot end forms cotyledons, or seed leaves, which channel nutrients to the

embryo.

There are two main groups of plants, the dicots (two cotyledons) and the

monocots (one cotyledon).

In monocots :

some of the endosperm remains and is channeled through the cotyledon after

germination.

The outer wall of the ovule becomes the seed coat.

In dicots :

the cotyledons absorb most of the endosperm and provide nutrients to the

embryo after germination.


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Plant tissue systems

Each organ of the plant has ALL three tissues:

1. dermal tissue

2. vascular tissue

3. ground tissue

What is/are function/s of

DERMAL TISSUE?

Protection, absorption, and

conservation of water

Dermal tissue is colored in white

Root

Leaf


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VASCULAR TISSUE?

Transport of material betweenroots and shoots (stems/leaves)

Vascular tissue is colored in purple

Xylem: transport of water

and dissolved minerals

Phloem: transport of sugars

(food)


GROUND TISSUE?

Photosynthesis, support, and

storage

Ground tissue is colored in yellow

Ground system surrounds the vascular tissue and comprises of:

1. parenchyma

2. collenchyma


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3. sclerenchyma


PARENCHYMA CELLS?

Photosynthesis, storage of starch,

composes the fleshy tissue of fruits

The typical cell, the cell walls

are relatively thin and flexible

Chloroplast


COLLENCHYMA CELLS?

Support of young plant shoot and petioles,

provides support without restraining growth

These cells have thicker

cell walls than parenchyma and

are grouped in strands or cylinders


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A i RS 1 2012/13 20


SCLERENCHYMA CELLS?

Support and transport

These cells have very thick

cell walls strengthened by lignin.

mature cells cannot elongate and

occur in regions of the plant that have

stopped growing. At functional

maturity, these cells are dead.

These cells make up the xylem.

Sclerenchyma exist as either sclereids or fiber form.

vascular plants with seeds-angiosperms

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