KINGDOM PLANTAE

OUTLINE OF THE KINGDOM PLANTAE

Two basic groups:-

NON-TRACHEOPHYTES

or non-vascular plants:

TRACHEOPHYTES

or vascular plants:

Tracheophytes

• are distinguished by conducting tissues:

xylem and phloem

Mosses sometimes have cells

which help water move through

the plant, but not tracheids.

Why is the term „non-tracheophyta‟ more

suitable than „nonvascular‟ to describe mosses?

TS „stem‟ of a moss

PLANTAE

(EMBRYOPHYTA)

NON VASCULAR

(NON TRACHEOPHYTA)

Liverworts, Hornworts, Mosses.

PHYLUM: (MOSSES)

BRYOPHYTA

VASCULAR

(TRACHEOPHYTA)

NON-SEED PLANTS

Club mosses, Horsetails, Whisk ferns, Ferns.

PHYLUM: (FERNS)

POLYPODIOPHYTA

SEED PLANTS

(SPERMATOPHYTA)

GYMNOSPERMATA

Cycads, Ginkgo, Conifers.

PHYLUM: (CONIFERS)

PINOPHYTA

ANGIOSPERMATA

(Flowering plants)

DICOTS MONOCOTS

PHYLUM: (FLOWERING PLANTS)

MAGNOLIOPHYTA[Pinophyta:

out of

syllabus]

Outline of the

Kingdom

Plantae

Division (old term) for

phylum in plants

Flowering plants

Cone-bearing plants

Ferns and their relatives

Mosses and their relatives

Green algae ancestor

Flowers; Seeds Enclosed in Fruit

Seeds

Water-Conducting (Vascular) Tissue

Land plants:

evolved from green algae (Charales).

all descend from a single common

ancestor.

Evolution of Plants

Chlorophyll a and b.

Starch as a storage product.

Cellulose in cell walls.

Plasmodesmata.

Plastids with double membrane

Chara

Land plants retain derived features

they share with green algae:

A plant is a multicellular eukaryote that

contains cellulose cell-walls, plasmodesmata,

plastids with double membrane, contain

chlorophylls a and b and show alternation of

generation.

What is a „plant‟?

The „land plants‟ are referred to as:

Embryophytes

A group of plants in which the embryo is

retained within the parental tissues

Embryophyta

A seed

Embryo is

protected by testa

in flowering plants

HOW DID LAND PLANTS ARISE?

• the green algal ancestors of

the land plants lived at the

margins of:

ponds

marshes

• it was from such a marginal habitat, which

was sometimes wet and sometimes dry, that

early plants made the transition onto land

forming a

green mat

To a Terrestrial

Habitat

Shift from an

Aquatic Habitat

400 - 500 million

years ago

What are the problems of the transition from water

to land?

1: Desiccation

waxy cuticle covers surfaces of

leaves.

2: Reproduction

delicate sex cells must be

protected

embryos are contained within

a protective structure

thick spore walls contain the

polymer sporopollenin protects

the spores from:

desiccation

resists decay is present Pollen grains

3) Support

air, unlike water, offers no support to the

plant body: lignified tissue evolved

4) Nutrition

plants require light and

carbon dioxide for

photosynthesis, so at least,

a part of the body must be

above the ground

minerals and water, are at

ground level or below the

ground, and to make

efficient use of these, part

of the plant must be below

the ground in darkness

5) Gaseous exchange for photosynthesis and respiration:

carbon dioxide

oxygen

stomata evolved to regulate gas exchange

must be exchanged with the

atmosphere rather than a

surrounding solution

Exchange

with water

6) Environmental variables

Water, provides a very

constant environment.

A terrestrial environment is

much more subject to

changes in:

temperature

pH

ionic concentration

light intensity

Certain pigments that

afford protection against

the mutagenic UV

radiation evolved.

Carotenoids protect plant against UV

Plant Life Cycles

Plants exhibit an alternation of generations – the

diploid generation, or sporophyte alternates

with the haploid generation, or gametophyte.

Alternation of generations:

is a universal feature of the life cycles of land

plants

TWO features of alternation of

generations are:

1. The life cycle includes both a multicellular:

diploid stage

haploid stage.

2. Gametes are

produced by mitosis,

not be meiosis.

Meiosis produces

spores that develop

into multicellular

haploid organisms

In the bryophytes, the gametophyte

is the DOMINANT GENERATION

The gametophyte is:

larger

longer-lived

more self-sufficient

The sporophyte is:

small

often brown

sporophyte

gametophyte

than the

sporophyte

by the time

spores are

released

In the tracheophytes, the sporophyte

is the DOMINANT GENERATION

The sporophyte is:

larger

longer-lived

more self-sufficient

The gametophytes in flowering

plants are:

• nutritionally dependent on the

sporophytes

• enclosed within the

sporophyte tissues

Male and Female gametophytes

in Flowering Plants

Consist of only a small group of cells

entirely dependent on the sporophyte

Female gametophyte:

Contents of embryo sac

Male

gametophyte:

Contents of

pollen tube

Male gametophyte in Flowering

Plants

In the seed plants, this evolutionary

trend :

has led to a condition in which water

is not required for the sperm to

reach the egg

Female gametophyte in

Flowering Plants

Alternation of generations

Trends observed in the plant groups: 1) a reduction of the gametophyte

1-5 cm in

mosses

1 cm in ferns

A few cells in

flowering plants

Gametangia are organs in bryophytes, ferns,

and gymnosperms where gametes are

produced.

Male gametangium:

antheridium (produces

sperm)

Sperm

cells egg

Female gametangium:

archegonium (produces

and retains egg cells)

2) A loss of multicellular GAMETANGIA (structures in

which gametes are produced. Singular: gametangium)

No antherida and archegonia in Magnoliophyta.

3) Increasing specialisation for life on land

Pollen eliminated the

liquid-water requirement

for fertilisation

Sperm cells swim

through a film of

water in mosses &

ferns Developing a means

of transport & support

Developing a

waxy cuticle

Developing stomata

Summary of some features of the three

phyla making up the land plants

Phylum Evolutionary

state

Dominant

generation

Need water

for

fertilisation

Gametangia

Bryophyta Primitive Gametophyte Yes Present

Polypodiophyta More

advanced

Sporophyte Yes Present

Magnoliophyta Most evolved Sporophyte No Absent

The non-vascular

(nontracheophyte) plants

no marine, some freshwater and most are

terrestrial

never evolved into large plants

have little or no water-transporting tissue

some mosses have cells

called hydroids:

die

provide channels in

which water can travel.

The non-vascular

(nontracheophyte) plants

many grow in dense masses, through which

water can move by capillary action

the „leafy‟ structure

readily catches and

holds water that

splashes onto them

„leaf‟ is one-cell

thick in mosses

The non-vascular

(nontracheophyte) plants

plants are small enough that

minerals can be distributed

internally by diffusion

lack the leaves, stems and roots

that characterise the vascular

plants, although they have

structures analogous to each

Funaria

Plant body is called thallus

(plural: thalli)

Funaria structure

„Leaf‟ spiral

arrangement

The non-vascular

(nontracheophyte) plants

a waxy covering that retards water loss is:

absent in some species

very thin and so not effective in others

They grow in shady, moist

environments in dense mats.

Polytrichum commune

is exceptionally tall.

40 cm

Stomata only in capsule

Cannot be tall:

- No lignin

- No proper anchorage

- No vascular system

THE LIFE CYCLE OF MOSSES

(Phylum: BRYOPHYTA)

BRYOPHYTA [Mosses] Funaria

Bryum

Tortula

Locally found

examples

MOSS

Life

Cycle

Diploid sporophyte is small

Capsule on a stalk (seta)

Meiosis produces spores

Green initially, but

becomes brown and non-

photosynthetic

Haploid gametophyte is dominant

- Large & long-lived

- Photosynthetic

- Mitosis produces gametes

Gametophytes:

Multicellular gametangia form at the tips of

gametophytes

Archegonia

Female gametangia Antheridia

Male gametangia

paraphyses

Paraphyses (singular: paraphysis): (sterile

hairs between sex organs) retain moisture

paraphyses

Archegonium

Mature

Immature

Development of archegonia

Antheridium

[immature]

Lid cell is removed to release the sperm

Sperm with two flagella:

biflagellated

Sperm are flagellated

and must swim to egg

through drops of

water.

Development of the calyptra of a moss

Calyptra: remains of archegonium

Function: temporary, protective covering

a. Neck canal

cells present b. Archegonium

after fertilisation

c. Elongated seta

with calyptra on

top of it

d. Capsule fully

developed

Spore dispersal

Gametophyte

Seta

Spore capsule

Peristome teeth

Operculum falls off

Calyptra

Operculum is shed as water is lost

from annulus

Peristome

teeth

Annulus

Peristome teeth bend outwards:

Spores sift through gaps.

Spore dispersal in dry conditions in Funaria.

Peristome teeth move in response to changes in

atmospheric humidity (hygroscopic).

Serve to ensure spore release only during favorable

conditions (dry for some species; moist for others).

Apophysis:

swelling of the seta

immediately behind capsule;

stomata + photosynthesis in

some

Section through a capsule

Annulus:

helps regulate passage of

spores out of capsule;

undergoes hygroscopic

movements Annulus

Apophysis

Spores germinate into a protonema

(plural: protonemata)

a branched, filamentous

structure unique to

mosses

protonema is the YOUNG

gametophyte (F)

Stages of spore germination

(A-C) and gametophyte

development (D-F)

Some filaments are:

photosynthetic

rhizoids that anchor the

protonema.

Tips of photosynthetic

filaments form buds

which produce the leafy

moss shoots.

Bud

Rhizoids

May, 2011 Paper 2

Use your knowledge of biology to describe the

significance of the following.

Bryophytes can only thrive in moist environments.

(5 marks)

Waxy cuticle is absent or

inefficient.

Male gametes are

flagellated and need water

as a medium to swim

towards female gamete.

Tracheophytes

Vascular Plants

The xylem conducts water up

The phloem conducts food up/down

The sporophyte generation is dominant

Vascular Seedless Plants (Spores)

and

Vascular Seed Plants

Vascular Bundles

The evolution of tracheid cells had

two important consequences:

2. The stiff cell walls provided

rigid structural support

1. Tracheids provided a pathway for

the long-distance transport of:

water

mineral nutrients

POLYPODIOPHYTA :

Ferns

Locally found

examples

Dryopteris

Adiantum

English: Venus‟s-hair-fern

Maltese:Tursin il-bir

Traits that ferns share with the seed plants:

1) a vascular system

2) sporophytes as the dominant life stage

3) stomata

Ferns retain some ancestral features:

1) free-living gametophyte,

2) no seeds

3) motile sperm that require water for fertilisation

1. fronds – large leaves with complex vasculature

2. spores on underside of pinnules

Ferns are characterised by:-

3. absence of seeds

4. requirement for water for the transport of the

male gametes to the female gametes

Ferns are characterised by:-

Multiflagellated

sperm

Fig. 15 Fern sporophyte, detail of

frond structure.

Root

For anchorage and to

absorb water + ions

Vascular

Rhizome

A horizontal underground stem

from which roots arise

Does not absorb water or ions

Vascular

Rhizoids

No vascular tissue

For anchorage

Minimal or no absorption

Fern Sporophyte consists of:

Rhizomes, adventitous roots and fronds

pinna

pinnule

rachis

(main midrib)

Sporophytes have true roots,

stems, and leaves.

Fern leaf starts development

as a coiled “fiddlehead.”

Detail of a fiddlehead

Fronds (leaves) develop at the tip of the

rhizome as tightly rolled-up coils called

fiddleheads

-They unroll and expand

Compared to mosses, the fern sporophyte

shows much greater:

Moss:

a few cm

Fern: up to 20m development,

Independence

dominance

Sporophyte can be

very large and

sometimes

survives for

hundreds of years.

Sporangia occur on undersides of fronds in clusters

called sori (singular: sorus)

Each sorus contains many sporangia (spore cases)

sorus

Sori in different species

Dryopteris

Adiantum

Section through a sorus

Section through a sorus

Indusium

Section through a sorus

Thick-walled

annulus

Sporangium

Spores

Thin-walled stomium

has ruptured

Mature fern sporangium

Sporangia walls are only one

cell thick, borne on a stalk.

Spore mother cells in sporangia form haploid

unicellular spores by meiosis.

The single-celled

spore is a resting

stage.

Spores develop into a multicellular

haploid plant: the gametophyte

(prothallus) - by mitosis.

Stomium: a region of thin-walled cells in

certain spore-producing structures that

ruptures to release the spores.

Annulus: A ring or group of thick-

walled cells around the sporangia

of many ferns that functions in sp

ore release.

Dryopteris sporangium

At maturity, the spores are

catapulted by snapping action.

Mature

sporangium

Dehisced sporangium

with annulus bent back

Annulus recoil

propelling spores

into the air

Germinating fern spore

Spores can be blown by wind and develop

into gametophyte far from parent plant.

The gametophyte is:

• a thin heart-shaped plate of cells about

1cm in diameter = prothallus (unique)

• is green and photosynthetic, anchored

by rhizoids

• lacks a cuticle and so survives only in

damp conditions

Rhizoid

1cm

Dryopteris

150 cm in height in Dryopteris

1cm

Prothallus is

short-lived

Sporophyte is

long-lived Sporophyte and prothallus

are:

both photosynthetic

independent plants

Rhizoid

Rhizoid

Fern gametophytes produce

antheridia and archegonia, on their

underside.

When conditions are right, the sperm swims from

the male antheridium to fertilise the egg in the

archegonium

A new adult (sporophyte)

fern plant will grow from the

prothallus

Sporophyte

Gametophyte

(prothallus)

Rhizoid

Root of young

sporophyte

Rhizoids

The sporophyte

continues to grow

while the

gametophyte dies.

Ferns are well-suited to moist and shaded

areas, but do not do well in arid habitats. Give

TWO reasons.

1. Sperm need water to swim in.

2. Gametophyte lacks a cuticle.

Fern

Life

Cycle

HOMOSPORY vs HETEROSPORY

The most ancient vascular plants were homosporous - a single type of spore.

The spores produce one type of gametophyte that has both archegonium and antheridium.

Mosses & most ferns = HOMOSPOROUS

Megaspore

develops into female

gametophyte:

megagametophyte

are produced in

small numbers in

megasporangia

Heterospory: 2 types of spores-Angiosperms

Microspore

develops into male

gametophyte:

microgametophyte

are produced in

large numbers in

microsporangia

Homospory

Heterospory

The diagram illustrates the life cycle of a typical fern.

a) Indicate whether each stage is haploid or diploid by writing

n or 2n in the circles provided.

b) Which is the dominant generation?

c) Does the life-cycle illustrated show:

heterospory? yes / no

alternation of generation? yes / no

syngamy? yes / no

Sporophyll: a modified

leaf that bears sporangia

ANSWER

b) Which is the dominant generation? Sporophyte

c) Does the life-cycle illustrated show:

heterospory? yes / no

alternation of generation? yes / no

syngamy? yes / no

MAGNOLIOPHYTA : Flowering Plants

Angiosperms: are found in a wide range

of habitats

have re-established

themselves in fresh water

& the sea

Victoria amazonica-

flower & leaves

Posidonia oceanica

Neptune grass

Alka

Dead

Posidonia

leaves -

banquettes

Angiosperms and animals have affected one

another‟s evolution

Coevolution is the mutual influence on

the evolution of two different species

interacting with each other and reciprocally

influencing each other‟s adaptations.

Flowering plants are extremely well

suited to life on land, in their :

1. morphology

e.g. efficient water-carrying xylem vessels

2. reproduction

seeds enclosed in

an ovary

develop directly into sporophytes which

either:

survive or

die

Embryos of seedless plants :

depending on

environmental conditions –

no resting stage

• is a well-protected resting stage for the

embryo

• seeds of some species may remain viable

(able to grow) for many years

Seed of a gymnosperm or

angiosperm:-

Judean date palm seed about

2,000 years old, was

germinated in 2005

drying

predators from eating the food reserves or

embryo during the resting stage

Seed coat protects embryo from:

Many seeds have structural adaptations

that promote dispersal by wind or animals

Wings:

wind dispersal.

Seeds within berries

are often dispersed in

animal feces.

The barbs of cockleburs

facilitate seed dispersal by

allowing the fruits to

“hitchhike” on animals.

Angiosperms are divided into

monocots and dicots

List of characteristics of angiosperms Double fertilisation

Triploid endosperm

Have flowers

Produce seeds enclosed in fruit

Xylem contains vessel elements

Phloem contains companion cells

Gametophyte greatly reduced and is endosporic

Sporophyte is the dominant generation

Heterosporous

Dia

gn

os

tic f

eatu

res

Alternation

of

generations

Alternation of Generations: Angiosperms

Diploid

Sporophyte:

Leaves

Stem

Roots

macroscopic parts

of flowers

Haploid Gametophytes are:

reduced to a few cells

retained within the sporophyte (endosporic)

nutritionally dependent on sporophyte

Contents of

pollen grain

angiosperms are heterosporous plants

the pollen of seed plants has evolved

mechanisms for dispersal, so liquid water is

not needed for the transfer of male gametes

Pollen grains: Microspores

Embryosac: Megaspore Wings – pollen

carried by wind

Hooks- pollen

carried by insects

Male gametophyte (Microgametophyte)

Pollen grain = microspore

Contents of pollen grain =

male gametophyte

Male gametophytes reach

female gametophytes by

producing a pollen tube

Thus, there is no need for water

for fertilisation in angiosperms

[i.e. can thrive in dry habitats]

tube

nucleus

pollen

tube

generative

nucleus

Female gametophyte (Megagametophyte)

Embryosac =

Megaspore

Contents of embryosac

= female gametophyte

Ovule

DOUBLE FERTILISATION - two male gametes

participate in fertilisation [unique process]

- One sperm combines with the egg = diploid ZYGOTE

- The other sperm combines with 2 polar nuclei = triploid

ENDOSPERM (nourishes developing sporophyte)

DOUBLE FERTILISATION

A closer look at the megagametophyte

Endospermic tissue formation

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

Statement

Life cycles

Moss Flowering

plant

Alternation between haploid & diploid phases.

Meiosis occurs at gamete formation.

Involves production of spores.

Sporophyte generation is dominant.

Female gametes develop within archegonia.

Reproduction results in seed formation.

Gametophyte is an independent plant.

Produces flagellated male gametes.

Double fertilisation occurs.

If the statement is correct for that life cycle, place a tick () in the

appropriate box and if the statement is incorrect place a cross ().

SHORT QUESTIONS: [1995]

1. The figure represents a

generalised life cycle of a

terrestrial plant.

a) By placing the symbols n

and 2n in the circles, indicate

which stages in the cycle are

haploid and which are diploid.

b) Indicate clearly by the use of arrowheads, the

direction of the cycle in the figure shown.

c) What types of nuclear division occur at X and at

Y? (5)

n

2n

n

n

2n

mitosis

meiosis

THE END