Highlights of Plant Evolution

Alternation of Generation

Both a __________ haploid and __________ diploid stages in the life cycles.

Classification of Seedless Plants (Kingdom: Plantae)• Nonvascular

Seedless plants– _____________

• Mosses– Hepatophyta

• Liverworts– Anthocerophyta

• Hornworts

• Vascular Seedless plants– Lycophyta

• Club mosses

– Psilophyta• Whiskferns

– Spenophyta• Horsetails

– _____________• Ferns

Kingdom Plantae – currently defined as plants with embryos)

We will treat all of these as separate “divisions”

Bryophytes - Nonvascular Seedless Plants

• Plant is a thallus (no vascular tissue)– no true leaves, roots, stems

• __________/_________:– Gametophyte

• (antheridium and archegonium)

– sporangium (produces spores)

Gametophyte Sporophyte

Hepatophyta• Liverworts

– Two forms• __________ (80%)• __________ (20%)

Hepatophyta

• Liverworts– Reproduction

• Asexual

(_______________)

• sexual

Anthocerophyta

____________

BryophytaMosses

Moss gametophytes grow more vertically than horizontally

Bryophyta

Essay!

Pteridophytes - Vascular Seedless Plants

• Formation of vascular tissue– __________ (water)– __________ (food)– True leaves, roots, and stems

• Lignin (chemical in cell wall)• Sporophyte generation

dominate• Sperm with flagella

Lycophyta

• Lycophytes– true leaves

• Microphylls – small, usually spine shaped leaves with a single vein.

– true stems– true roots– ____________

• leaves that produce spores

Psilophyta

Sphenophyta

• Horsetails– true leaves

• microphylls

– true stems• silica

– true roots

Fern Life Cycle

Essay!

PlantaePlantae

Seed PlantsSeed Plants

Vascular Plants

• Formation of vascular tissue– Xylem (water)– Phloem (food)– True leaves, roots, and stems

• Lignin• ____________ generation dominate

Alternation of Generation

Alternation of Generation• Sporophyte dependent on

gametophyte– mosses

• Large sporophyte and small independent gametophyte– ferns

• Gametophyte dependent on sporophyte– seed plants

Why be Sporophyte Dominant?

• Reduced mutations– UV light harmful to DNA– Diploid (2n) form copes better with

mutations• two alleles

Why Retain Gametophyte Generation?

• Ability to screen alleles– doesn’t require a large amount of

energy

• Sporophyte embryos rely on some gametophyte tissue

Seeds• A seed is a sporophyte in

a package– spores are only single cells– packaged with food

• All seed plants are _____________ (more than one kind of spore)– megasporangia– microsporangia

From Ovule to Seed

Whole structure

Develops from megaspore

Embryo, food supply, protective coat

Overview of Seed Plants• Produce Seeds

– Can remain dormant for years– Pollination replaces swimming sperm

• Gametophyte generation reduced– Gymnosperms lack antheridium– Angiosperms lack both archegonium

and antheridium

Phylogeny

Gymnosperms(Naked Seed)

• Division: Cycadophyta• Division: Ginkgophyta• Division: Gnetophyta• Division: Coniferophyta

Ginkgophyta• Ginkgo or Maidenhair Tree• Characteristic leaves• Only one species• Only ______ are planted

Cycadophyta

• Cycads• Palm-like plants

– Sago Palms

• Leaves in cluster at top of trunks

• True __________

Gnetophyta• 3 Genera• Ephedra• Mormon Tea

– ____________• raises heart rate• raises blood

pressure

Coniferophyta

Coniferophyta

• Pine tree is the sporophyte generation

• Contains both male and female cones– Pollen (___________)

cones (low in tree)• produces pollen

– Ovulate cones (high in tree) with scales

• produces seeds

Pine Life Cycle• No Antheridium (microsporangia)

produce pollen grain (4 cells)– 2 prothallial cells– 1 generative cell

»produces 2 sperm– 1 tube cell– __________ for dispersal

Pine Life Cycle• Ovule in a ovulate cone

– integument (seed coat) (2n)– megasporangia or nucellus (nutrition)

(2n)– 4 _______________ from female

gametophyte (3 die)• develops into female gametophyte

– archegonium with eggs (n)

Angiosperms

Angiosperm

Flower• Sepals• Petals• Receptacle (part

of the stem)

• Stamen– Anther– Filament

• Carpel– Stigma– Style– Ovary with ovule

Angiosperm Life Cycle

Angiosperm Life Cycle• No Antheridium (microsporangia -

diploid)• produce pollen grain

– 1 ___________ cell »produces 2 sperm

– 1 tube cell

Angiosperm Life Cycle• Ovule in Ovary

– megasporangia – produces 4 megaspores (3 die)

• remaining one develops into female gametophyte called the _____________

Angiosperm Life Cycle• Embryo sac (Female Gametophyte)

consists of:– 7 cells (eight nuclei) due to 3 mitotic

divisions• 3 ___________• 2 polar nuclei (one cell)• 2 __________• 1 egg

Angiosperm Life Cycle• Double fertilization

– one sperm unites with egg– one sperm unites with polar nuclei

• develops into endosperm (3n)

• Fruit and Seed development– ovule = seed– ovary = fruit

Angiosperm Life Cycle

Cross Pollination

Angiosperm Radiation• Begins the Cenozoic era (65 mya)• Most closely related to the

Gnetophyta• __________

– the mutual influence of two species on each other

– plants and animals (insects, birds, bats)