biology 1030 [7] - plant diversity 09 w live...

Biology 1030 Winter 2009

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Plant DiversityChapter 29 (573-588)Chapter 30 (591-606)

Scott circa 2009

What is a Plant?• Plants are characterized by multiple traits:

– AutotrophicAutotrophic

– Cell walls

– Storage material is starch

– Bodies made of three organ types

– Haplodiplontic life cycle

Scott circa 2009

• Two multicellular stages

– They have tissues which develop from apical meristems


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Plant Phyla• ~300,000 species

• 10 phyla exist

• Three major groups– Bryophytes

• Bryophyta – mosses

– Seedless vascular plants• Pterophyta ferns

Scott circa 2009

• Pterophyta – ferns

– Seed plants• Coniferophyta – conifers

• Anthophyta – flowering plants

Phyla You Don’t Need to Know• You are not responsible to know these phyla

– Hepatophytap p y

– Anthocerophyta

– Lycophyta

– Cycadophyta

– Ginkophyta

– Gnetophyta

Scott circa 2009


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Alternation of Generations• Two multicellular stages

– Gametes (n)

Gametophyte

nMitosisMitosis

– Zygote• Mitosis

– Sporophyte• Meiosis

– Spores• Mitosis

n

n

Gamete

FERTILIZATIONMEIOSIS

n

n

Spore

Scott circa 2009

Mitosis

– Gametophyte

– Gametes

2n Zygote

Mitosis

Sporophyte

Sporophytes• Multicellular, diploid

– Grow from zygote

May have vascular tissue– May have vascular tissue

• Function– Sporangia (sporangium)

Spores

Scott circa 2009

– Sporocytes Spores

Sporangium


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Gametophytes• Multicellular, haploid

– Grow from spores

Never have vascular tissue– Never have vascular tissue

• Function– Gametangia

• Archegonia (female) • Antheridia (male)

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Eggs Sperm(inside)

Basic Plant Body• Three organs

• Below ground

Apical bud

g1. Roots

• Above ground2. Stems (shoots)

3. Leaves

Shootsystem

Vegetativeshoot

Leaf

St

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• Vascular tissue

• Waxy cuticle

Stem

Rootsystem


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Evolution of Land Plants1. Green algae ancestor

2. Non-vascular plants– Bryophytes

3 V l l t

• Apparent trends– True organs

– Dominant generation3. Vascular plants

– Non-seed plants

– Seed plants

– Dependency on water

– Size and complexity

1GREENALGA

Liverworts

Hornworts

Mosses

Scott circa 2009

2

3

Lycophytes (club mosses,spike mosses, quillworts)

Pterophytes (ferns,horsetails, whisk ferns)

Gymnosperms

Angiosperms

Millions of years ago (mya)500 450 400 350 300 50 0

Phylum Bryophyta• Perennial gametophyte

– Protonema(ta)

Gametophores– Gametophores

– Apical meristem

• Dioecious gametophytes– Male & female

– Gametangia on mature plants

Scott circa 2009


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Bryophyta Body Plans• Gametophyte

– No xylem or phloem• Non-vascular• Non-vascular

• Impact on size

– No true organs• Thin ‘leaves’

• Simple ‘stems’

• Small ‘rhizoids’

Scott circa 2009

– No cuticle• Impact on environment

= A thallus

Bryophyta Body Plans• Sporophyte

– Dependent on the gametophyte• Grows onGrows on

• Fed by

– Foot– Seta– Sporangium

• Homosporous

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Moss Water Loss• All habitats

• Desiccation can occur in many

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Life on Dry Land

• Evolution of specific structures: – Transport tissue

• Xylem & Phloem– Epidermal secretions

• Cuticle

• Xylem & Phloem

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Vasculartissue


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Vascular Plants• Sporophyte

dominantLong lived– Long-lived

– Most are perennial

• Three true organs– Roots

– Shoots

Leaves

Scott circa 2009

– Leaves

• Three tissue types– Ground

– Dermal

– Vascular

• Three cell types– Parenchyma

– Collenchyma

– Sclerenchyma

Phylum Pterophyta• The ferns

– Seedless vascular plants

• Sporophyte dominant– Perennial

– Independent gamteophyte

Scott circa 2009


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Pterophyta Body Plans• Short-lived gametophyte

– Thallus• Prothallium emerges• Prothallium emerges

– Small, photosynthetic

• Hormonal sex determination– Hermaphroditic gametophyte

• Antheridiogen

Scott circa 2009

g

– Male gametophyte

Pterophyta Body Plans• Long-lived sporophyte

– True organs

– Underground stem (= rhizome)

– Compound leaves (fronds)• Fiddlehead

– RootsLeaves

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• Shoot apical meristem

• Root apical meristems Rhizome

Roots


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Pterophyta Body Plans• Sporangia on leaves

– Sporophylls

Annulus– Annulus

– Sporocytes • Homospores

• Clustered in sori (sorus)– Indusium

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The Seed Plants• Heterosporous spore production

– Megaspores

Microspores– Microspores

• Dioecious gametophytes– Very small

– Dependent

• Ovule develops into the seed

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Ovule develops into the seed– Fertilization

• Pollen grain– Carries sperm


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Reduced Gametophytes• Trend

–

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• Retention in megasporangium– Protection

• Gymnosperms

• Sporophyte tissueI t t

Ovules & Seeds

– Integument

– Megasporangium

• One megaspore

• Megagametophyte– Microscopic

Scott circa 2009

– Archegonia

• Fertilization– Nutritive tissue

• Angiosperms


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Pollen Grains• Sporophytes house gametophytes

– Cross fertilization

• Sperm transfer vessels– Not dependent on water

• Male gametophytes

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– Incredibly reduced

Pollen Grains• Dispersal

– Wind

Wind & animals– Wind & animals

• Pollination– Direct

– Indirect

• Pollen tube forms

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• Pollen tube forms– Sperm transfer

– Fertilization IN ovule


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Phylum Coniferophyta• Gymnosperms (naked seeds)

• Sporophyte dominant

• Cones– Pollen cone – microsporangia

• Microsporophylls

– Ovulate cone – megasporangia • Megasprorphylls

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Coniferophyta Body Plans• Sporophytes

• Most are evergreensL i l dl– Leaves are simple needles

– Thick cuticle

• Very long lived

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Coniferophyta Body Plans• Megagametophyte

• Microscopic – 1000s of cells2 6 h i– 2-6 archegonia

• Fully dependent

• Nutrition source

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Coniferophyta Body Plans• Microgametophyte

• Microscopic – 4 cells1 t b ll– 1 tube cell

– 2 prothallial cells

– 1 generative cell

• Exine – coat

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• Generative cell division– Produces 2 sperm


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Coniferophyta Pollination• Sperm transfer

– Advantages

• Direct pollination– Can be a long process

• Ovule forms a naked seed

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Anthophyta• Angiosperms (enclosed seeds)

• Sporophyte dominant

• The flowering plants– Very successful group

• Sporangia contained in a flower

Scott circa 2009

– Stamen – microsporangia

– Carpel – megasporangia

• Can be found in every environment


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Anthophyta Body Plans• Sporophytes

• Two major groupsM t– Monocots

– (Eu)dicots

– Seed leaves

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Sporophyte Body Plans• Embryos

– Seed leaves

• Leaf venation

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• Stem vascular tissue


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Sporophyte Body Plans• Roots

• Pollen grains

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• Flowers

Anthophyta Body Plans• Megagametophyte

• Microscopic – 7 cells (8 nuclei)P th lli l ( ti d l)– Prothallial (antipodal)

– Syngergids

– Egg

– Polar nuclei

N h i

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• No archegonia


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Anthophyta Body Plans• Microgametophyte

• Microscopic – only 2 cells!T b ll– Tube cell

– Generative cell

• Exine – coat

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• 2 sperm cells– Double fertilization

Anthophyta Pollination

• Sperm transfer– Advantages

Pollen grain

Stigma

• Indirect pollination– Double fertilization

• Seeds are enclosed

Pollen tube

Style

2 sperm

Scott circa 2009

in a fruit Ovary

Ovule

Micropyle


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Fruit

• Expanded flower parts FlowerCarpels

OvaryStamen

Stigma

Ovule

Seed

Carpel(fruitlet)

Stigma

Ovary

Stamen

OvuleSepal

Ovary(in receptacle)

Sepals

Remains ofstamens and styles

Scott circa 2009

y

Stamen

SeedReceptacle

biology 1030 [7] - plant diversity 09 w live...

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