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
Kingdom Plantae – currently defined as plants with embryos)
– Lycophyta
• Club mosses
– Psilophyta
• Whiskferns
– Spenophyta
• Horsetails
– _____________
• Ferns
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)

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

Hepatophyta
• Liverworts
– Reproduction
• Asexual
(_______________)
• sexual

Anthocerophyta
____________

Bryophyta
Mosses

Moss gametophytes grow more vertically than horizontally
Essay!
Bryophyta

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!

Seed 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
Develops from megaspore
Whole structure 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

• Sepals
Flower
• 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)