unit 3 biodiversity of plants

UNIT 3: BIODIVERSITY

OF PLANTS

Campbell & Reece (2010); Chapter 29 and 30

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290, 000 known plant species

Land plants enabled survival of other life forms on land – including animals

Roots provide habitats, stabilize landscapes

Oxygen supply

Ultimate provider of food eaten by terrestrial animals

Common (derived) traits of land plants –separate them from ancestral plants (algal relatives):

Alteration of generations & multicellular, dependent embryo’s

Walled spores produced in sporangia

Multicellular gametangia

Apical meristems

Alteration of Generations

The life cycle includes bothmulticellular haploid (n) &multicellular diploid (2n) organisms

Multicellular, Dependent EmbryosAfter fertilization zygote develops into a multicellular embryo within maternal structures.

Maternal tissues provide nutrients.Embryo is dependent Land plant called embryophytes.

Walled Spores Produced in SporangiaSporophyte produces spores in organs called

sporangia

Diploid cells called sporocytes undergo

meiosis – generate (n) spores

Spore walls contain

sporopollenin:

resistant to harsh

environments

Multicellular GametangiaGametes produced in multicellular organs – gametangia.

Female gametangia – archegonia – produce single egg

Male gametangia – antheridia - produce & release sperm– fertilize egg internally within the archegonium

Apical MeristemsPlants sustain continual growth in

apical meristems

Cells from apical meristems differentiate into various

tissues

1) Elongation of the roots Nutrients & water from soil

2) Growth of stems & leaves More area for photosynthesis

GROUPING OF LAND PLANTS

• Ancestral species gave rise to a vast diversity of modern plants

• Land plants informally grouped based on presence or absence of vascular tissue

• Most plants have vascular tissue; these constitute the vascular plants

• Nonvascular plants are commonly called bryophytes

sites.google.com


• Seedless vascular plants can be divided:

– Lycophytes (club mosses and their relatives)

– Pterophytes (ferns and their relatives)

contrib.andrew.cmu.edu

quizlet.com

en.wikipedia.orgbiology.iastate.edu


• Seed plants

• A seed is an embryo and nutrients surrounded by a protective coat

• Seed plants can be divided into:

– Gymnosperms, the “naked seed” plants, including the conifers

– Angiosperms, the flowering plants

GYMNOSPERMS ANGIOSPERMS

visual.merriam-webster.com

bluebellnursery.com

• Conifers (seeds not enclosed)• “Naked seed”

• All flowering plants• 90% of living plant species• Seeds develop in ovaries –originate within flowers & mature into fruits

biology.iastate.edu

ucadia.com

Bryophyta (non-vascular plants) (p. 606 – 609)

• Phylum includes all mosses (Bryophyta)

• Bryophytes: all non-vascular plants

– Include liverworts, hornworts & mosses

• Mosses show alternation of generations

– i.e. have sporophyte & gametophyte generation

tolweb.orgflickrhivemind.netbryophytes.plant.siu.edu anbg.gov.au forums.gardenweb.com

Bryophyta

• In all bryophytes gametophytes are dominant in life cycle

• Larger & longer living than sporophyte

tolweb.orgflickrhivemind.netbryophytes.plant.siu.edu forums.gardenweb.combotany.hawaii.edu

Key

Haploid (n)

Diploid (2n) Protonemata(n)

“Bud”

“Bud”

Malegametophyte(n)

Femalegametophyte (n)

Gametophore

Rhizoid

Spores

Sporedispersal

Peristome

Sporangium

MEIOSIS SetaCapsule(sporangium)

Foot

Maturesporophytes

Capsule withperistome (SEM)

Femalegametophytes

2 m

m

Raindrop

Sperm

Antheridia

Egg

Archegonia

FERTILIZATION

(within archegonium)Zygote(2n)

Embryo

Archegonium

Youngsporophyte(2n)

THE MOSS LIFE CYCLED:\Chapter_29\A_PowerPoint_Lectures\29_Lecture_Presentation\29_08MossLifeCycle_A.html

Key

Haploid (n)


“Bud”

“Bud”

Malegametophyte(n)


Gametophore

Rhizoid

Spores

Sporedispersal

Peristome

Sporangium


Foot

Maturesporophytes


Femalegametophytes

2 m

m

THE MOSS LIFE CYCLE

Key

Haploid (n)


“Bud”

“Bud”

Malegametophyte(n)


Gametophore

Rhizoid

Spores

Sporedispersal

Peristome

Sporangium


Foot

Maturesporophytes


Femalegametophytes

2 m

m

Raindrop

Sperm

Antheridia

Egg

Archegonia

FERTILIZATION

(within archegonium)

THE MOSS LIFE CYCLE

Key

Haploid (n)


“Bud”

“Bud”

Malegametophyte(n)


Gametophore

Rhizoid

Spores

Sporedispersal

Peristome

Sporangium


Foot

Maturesporophytes


Femalegametophytes

2 m

m

Raindrop

Sperm

Antheridia

Egg

Archegonia

FERTILIZATION

(within archegonium)Zygote(2n)

Embryo

Archegonium

Youngsporophyte(2n)

THE MOSS LIFE CYCLED:\Chapter_29\A_PowerPoint_Lectures\29_Lecture_Presentation\29_13FernLifeCycle_A.html

VASCULAR PLANTS

LIVING VASCULAR PLANTS CHARACTERISED BY:

• Life cycles with dominant sporophytes

– Fern life cycle

• Transport in vascular tissues

– Xylem and phloem

• Well-developed roots and leaves

– Including spore bearing leaves called sporophylls

Pterophyta(p. 610 – 615)

• Phylum includes all ferns, horsetails & whisk ferns

• Vascular seedless plants– Vascular means plants could grow taller than bryophytes

• Ferns show alternation of generations (dominant sporophyte)

• Sperm flagellated – must swim through water to reach eggs i.e. found in damp environments


Key

Haploid (n)

Diploid (2n)

MEIOSISSporedispersal

Sporangium

SporangiumMaturesporophyte(2n)

Sorus

Fiddlehead

Spore(n)

Younggametophyte

Maturegametophyte(n) Archegonium

Egg

Antheridium

Sperm

FERTILIZATION

Newsporophyte

Gametophyte

Zygote(2n)

THE FERN LIFE CYCLED:\Chapter_29\A_PowerPoint_Lectures\29_Lecture_Presentation\29_13FernLifeCycle_A.html

Key

Haploid (n)

Diploid (2n)


Sporangium


Sorus

Fiddlehead

THE FERN LIFE CYCLE

Key

Haploid (n)

Diploid (2n)


Sporangium


Sorus

Fiddlehead

Spore(n)

Younggametophyte


Egg

Antheridium

Sperm

FERTILIZATION

THE FERN LIFE CYCLE

Key

Haploid (n)

Diploid (2n)


Sporangium


Sorus

Fiddlehead

Spore(n)

Younggametophyte


Egg

Antheridium

Sperm

FERTILIZATION

Newsporophyte

Gametophyte

Zygote(2n)

THE FERN LIFE CYCLED:\Chapter_29\A_PowerPoint_Lectures\29_Lecture_Presentation\29_13FernLifeCycle_A.html

Transport in Vascular Tissues

• Two types of vascular tissue:

• Xylem and phloem

• Xylem conducts water & minerals

• Dead cells called tracheids

• Phloem distributes sugars, amino acids, & other organic products

• Consists of living cells

• Water-conducting cells are strengthened by ligninand provide structural support

Evolution of Roots

• Benefits of lignified vascular tissue below ground

• Instead of rhizoids, roots evolved

– May have evolve from subterranean stems

• Roots: organs to absorb water & nutrients from soil

• Also anchor vascular plants

Evolution of Leaves

• Leaves increase surface area of plant body

• Main photosynthetic organ of vascular plants

• Classified as:

– Microphylls (only lycophytes) – leaves with a single vein

– Megaphylls (all vascular plants) – highly branched vascular system

• Greater photosynthetic productivity

Sporophylls and Spore Variations

• Sporophylls are modified leaves with sporangia

• Sori are clusters of sporangia on the undersides of sporophylls

• Strobili are cone-like structures

formed from groups of sporophylls

• Most seedless vascular plants are homosporous• Produce one type of spore that develops into a bisexual

gametophyte

• All seed plants (and some seedless vascular plants) are heterosporous• Produce megaspores that give rise to female

gametophytes

• And microspores that give rise to male gametophytes

Sporophylls and Spore Variations

SEED PLANTS

• Seeds changed the course of plant evolution

– Plants with seeds would become dominant producers in most terrestrial ecosystems

• Living seed plants can be divided into two:

– Gymnosperms

– Angiosperms

• A seed consists of an embryo and nutrients surrounded by a protective coat

SEED PLANTS

5 DERIVED TRAITS: (COMMON TO ALL SEED PLANTS)

1. Reduced gametophytes

– Develop in walls of spores that are retained in tissues of parent sporophyte

2. Heterospory

– Megasporangia produce megaspores (female gametophytes)

– Microsporangia produce microspores (male gametophytes)

SEED PLANTS3. Ovules

– An ovule consists of a megasporangium, megaspore, and one or more protective integuments• Gymnosperm megaspores have one integument

• Angiosperm megaspores usually have two integuments

SEED PLANTS

4. Pollen– Microspores develop into pollen grains – contain male

gametophytes

– Pollination is the transfer of pollen to the part of a seed plant containing the ovules

Pollen eliminates need for film of water

Can be dispersed great distances by air or animals

If a pollen grain germinates, it gives rise to a pollen tube that discharges two sperm into the female gametophyte within the ovule

SEED PLANTS

5. Seeds

• Evolutionary advantages over spores:– May remain dormant for

days to years, until conditions are favorable for germination

– Transported long distances by wind or animals

Seed coat(derived fromintegument)

(c) Gymnosperm seed

Embryo (2n)(new sporophyte)

Food supply(femalegametophytetissue) (n)

(b) Fertilized ovule(a) Unfertilized ovule

Integument

Immature

female cone

Spore wall

Megasporangium

(2n)

Male gametophyte(within a germinatedpollen grain) (n)

Megaspore (n) Micropyle Pollen grain (n)

Egg nucleus (n)

Discharged

sperm nucleus (n)

Female

gametophyte (n)

SUMMARY

Gymnosperms(p. 618 – 625)

• Plants with ‘naked seeds’ not enclosed in ovaries

• Include conifers (pine tree) and cycads

• Three key features of the gymnosperm life cycle are:

1. Dominance of the sporophyte generation

2. Development of seeds from fertilized ovules

3. The transfer of sperm to ovules by pollen

• The life cycle of a pine provides an example


Microsporangium (2n)

Microsporocytes

(2n)

Pollengrains (n)

Pollencone

Microsporangia

MEIOSIS

Maturesporophyte(2n)

Haploid (n)

Diploid (2n)

Key

MEIOSIS

Survivingmegaspore (n)

Pollengrain

Megasporocyte (2n)

Ovule

Integument

Ovulatecone

FERTILIZATION

Pollentube

Femalegametophyte

Spermnucleus (n)

Egg nucleus (n)

Archegonium

Seedling

Seeds

Seed coat(2n)

Foodreserves(n)

Embryo(2n)

Megasporangium(2n)

THE PINE LIFE CYCLED:\Chapter_30\A_PowerPoint_Lectures\30_Lecture_Presentation\30_06PineLifeCycle_A.html


Microsporocytes

(2n)

Pollengrains (n)

Pollencone

Microsporangia

MEIOSIS


Haploid (n)

Diploid (2n)

Key

Ovulatecone

THE PINE LIFE CYCLE


Microsporocytes

(2n)

Pollengrains (n)

Pollencone

Microsporangia

MEIOSIS


Haploid (n)

Diploid (2n)

Key

MEIOSIS


Pollengrain

Megasporangium(2n)

Megasporocyte (2n)

Ovule

Integument

Ovulatecone

THE PINE LIFE CYCLE


Microsporocytes

(2n)

Pollengrains (n)

Pollencone

Microsporangia

MEIOSIS


Haploid (n)

Diploid (2n)

Key

MEIOSIS


Pollengrain

Megasporocyte (2n)

Ovule

Integument

Ovulatecone

FERTILIZATION

Pollentube

Femalegametophyte

Spermnucleus (n)

Egg nucleus (n)

Archegonium

Megasporangium(2n)

THE PINE LIFE CYCLE


Microsporocytes

(2n)

Pollengrains (n)

Pollencone

Microsporangia

MEIOSIS


Haploid (n)

Diploid (2n)

Key

MEIOSIS


Pollengrain

Megasporocyte (2n)

Ovule

Integument

Ovulatecone

FERTILIZATION

Pollentube

Femalegametophyte

Spermnucleus (n)

Egg nucleus (n)

Archegonium

Seedling

Seeds

Seed coat(2n)

Foodreserves(n)

Embryo(2n)

Megasporangium(2n)

THE PINE LIFE CYCLED:\Chapter_30\A_PowerPoint_Lectures\30_Lecture_Presentation\30_06PineLifeCycle_A.html

Angiosperms (p. 625 – 634)

• Most widespread and diverse of all plants

• Are seed plants with reproductive structures called flowers and fruits

• Characterised by enclosed seeds

• The flower is an angiosperm structure specialized for sexual reproduction

• Pollinated by insects, animals or wind


• A flower is a specialized shoot with up to four types of modified leaves:

– Sepals, which enclose the flower

– Petals, which are brightly colored and attract pollinators

– Stamens, which produce pollen on their terminal anthers

– Carpels, which produce ovules

• A carpel consists of an ovary at the base and a style leading up to a stigma, where pollen is received


• A fruit typically consists of a mature ovary but can also include other flower parts

• Fruits protect seeds and aid in their dispersal

• Mature fruits can be either fleshy or dry


• Various fruit adaptations help disperse seeds

• Seeds can be carried by wind, water, or animals to new locations

MEIOSIS

Key

Microsporangium

Microsporocytes (2n)

Generative cell

Anther

Tube cell

Pollengrains

Microspore(n)

Male gametophyte(in pollen grain)(n)

Mature flower onsporophyte plant(2n)

Haploid (n)

Diploid (2n)

MEIOSIS

Ovule (2n)

Ovary

Megasporangium(2n)

Megaspore(n)

Female gametophyte(embryo sac)

Antipodal cells

Central cell

Synergids

Egg (n)

Pollentube

Pollentube

Stigma

Sperm(n)

Discharged sperm nuclei (n)

FERTILIZATION

Germinatingseed

Embryo (2n)

Endosperm (3n)

Seed coat (2n)Seed

Nucleus ofdevelopingendosperm(3n)

Zygote (2n)Eggnucleus (n)

Style

Sperm

THE ANGIOSPERM LIFE CYCLE

MEIOSIS

Key

Microsporangium


Generative cell

Anther

Tube cell

Pollengrains

Microspore(n)



Haploid (n)

Diploid (2n)


MEIOSIS

Key

Microsporangium


Generative cell

Anther

Tube cell

Pollengrains

Microspore(n)



Haploid (n)

Diploid (2n)

MEIOSIS

Ovule (2n)

Ovary

Megasporangium(2n)

Megaspore(n)


Antipodal cells

Central cell

Synergids

Egg (n)


MEIOSIS

Key

Microsporangium


Generative cell

Anther

Tube cell

Pollengrains

Microspore(n)



Haploid (n)

Diploid (2n)

MEIOSIS

Ovule (2n)

Ovary

Megasporangium(2n)

Megaspore(n)


Antipodal cells

Central cell

Synergids

Egg (n)

Pollentube

Pollentube

Stigma

Sperm(n)


FERTILIZATION

Eggnucleus (n)

Style

Sperm


MEIOSIS

Key

Microsporangium


Generative cell

Anther

Tube cell

Pollengrains

Microspore(n)



Haploid (n)

Diploid (2n)

MEIOSIS

Ovule (2n)

Ovary

Megasporangium(2n)

Megaspore(n)


Antipodal cells

Central cell

Synergids

Egg (n)

Pollentube

Pollentube

Stigma

Sperm(n)


FERTILIZATION

Germinatingseed

Embryo (2n)

Endosperm (3n)

Seed coat (2n)Seed

Nucleus ofdevelopingendosperm(3n)

Zygote (2n)Eggnucleus (n)

Style

Sperm


Angiosperm Diversity

Monocots (one cotyledon)

¼ of angiosperm species

Eudicots (“true” dicots)

More than 2/3 angiosperm species

TWO MAIN GROUPS OF ANGIOSPERMS

HUMAN WELFARE

• No group of plants is more important to human survival than seed plants

• Plants are key sources of food, fuel, wood products, and medicine

• Our reliance on seed plants makes preservation of plant diversity critical

PRODUCTS FROM SEED PLANTS

• Most of our food comes from angiosperms

• Six crops (wheat, rice, maize, potatoes, cassava, and sweet potatoes) yield 80% of the calories consumed by humans

• Modern crops are products of relatively recent genetic change resulting from artificial selection

• Many seed plants provide wood

• Secondary compounds of seed plants are used in medicines

unit 3 biodiversity of plants

Technology

nonvascular plants

comseedless vascular

naked seed plants

protective coatseed

known plant speciesland

multicellular embryo

dependent land plant

dependent embryoswalled