DomainBacteria

DomainArchaea

DomainEukarya

Common ancestor

Kingdom: PlantsDomain Eukarya

Plant evolutionIt is thought that life evolved in the seas– 1st photosynthetic organisms were aquatic green algae

• 500 mya land plants evolved– special adaptations for life on dry land >protection from drying = desiccation >waxy cuticle

>gas exchange (through cuticle)-stomates

>water & nutrient conducting systems

-xylem & phloem>protection for embryo

-seeds

Plant Diversity

Bryophytesnon-vascularland plants

Pteridophytesseedless

vascular plants

Gymnospermpollen &

“naked” seeds

Angiospermflowers & fruit

pollen & seeds

vascular system = water conduction

mosses ferns

conifersflowering plants

colonization of land

Tracheophytes

xylem cells = tracheidsAncestral Protist

flowers

Animal vs. Plant life cycle

diploidmulticellular

individual2n

diploidmulticellularsporophyte

2n

haploidmulticellulargametophyte

1n

haploidunicellulargametes

1n

gametes1n

Animal Plant

alternation of generations

meiosis

fertilization

mitosis

mitosismitosis

fertilization

mitosis

no multicellularhaploid

meiosis

spores1nzygote 2n

zygote 2n

First land plants• Bryophytes: mosses & liverworts

– non-vascular• no water transport system• no true roots

– swimming sperm• flagellated sperm

– lifecycle dominated by haploid gametophyte stage• fuzzy moss plant you are

familiar with is haploid– spores for reproduction

• haploid cells which sprout to form gametophyte

diploidhaploid

Where mustmosses live?

First vascular plants• Pteridophytes: ferns

– vascular• water transport system• xylem, phloem, roots, leaves

– swimming sperm• flagellated sperm

– life cycle dominated by sporophyte stage• leafy fern plant you are familiar

with is diploid• fragile independent gametophyte

(prothallus)

– spores for reproduction• haploid cells which sprout

to form gametophyte

diploid

Where mustferns live?

haploid

diploid

Alternation of generations

haploid

produces male & female gametes

archegonia

antheridia

First seed plants

– Gymnosperm: conifers• vascular• seeds

– naked seeds (no fruit)

• pollen– contain male gametophyte

• life cycle dominated by sporophyte stage– coniferous trees are diploid– reduction of gametophyte protects delicate egg &

embryo in protective cones» protected from drought & UV radiation

Early Gymnosperm: ginkgo & Cycad

Cones & naked seeds

Why is pollen important?

• Pollen eliminated need for water fertilization– spreads through wind

& animals

• Why does it irritate noses? – See the spikes?

First flowering plants• Angiosperm: flowering plants

– vascular– flower

• specialized structure for sexual reproduction

– seeds within fruit-protection & nourishment for seed!– pollen– life cycle dominated by

sporophyte stage• trees & bushes are diploid• microscopic gametophyte

Anther

FilamentStamen

StigmaStyleOvary

Carpel

Sepal

Petal

Ovule

Flower• Modified shoot with 4 rings

of modified leaves– sepals– petals– stamens

• male

– carpel• female

sepalspetals

stamens

carpel

Identify the flower structures…

seed coat

endosperm(3n)

cotyledons

embryo (2n)

cotyledons = “seed” leaves,first leaves of new plantcotyledons = “seed” leaves,first leaves of new plant

Angiosperms: fruiting plants• Have fruits in many

forms• Seeds contain plant

embryo• Embryo consists of

cotyledons, endosperm, hypocotyl & epicotyl

• Seed offers…– protection for embryo– stored nutrients for

growth of embryo

Monocots & dicots

• Angiosperm are divide into 2 classes– dicots (eudicot)

• 2 cotyledons (seed leaves)• leaves with network of veins• woody plants, trees, shrubs, beans

– monocots• 1 cotyledon• leaves with parallel veins• grasses, palms, lilies

Comparison of Monocots & Dicots

Acknowledgements

• With thanks to

• Kim Foglia & her website “Explore Biology”– Specifically the power point from which this

was drawn– 13 Ch29Plants2008.ppt

Also:

http://www.daylilies.org/ahs_dictionary/monocotseedlingnew.jpg