Plantae

Plantae
Seed Plants
Vascular Plants
•  Formation of vascular tissue
– Xylem (water)
– Phloem (food)
– True leaves, roots, and stems
•  Lignin
Sporophyte
•  ____________
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
Heterosporous
_____________
(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:
•  Division:
•  Division:
•  Division:
Cycadophyta
Ginkgophyta
Gnetophyta
Coniferophyta
Ginkgophyta
•  Ginkgo or Maidenhair Tree
•  Characteristic leaves
•  Only one species
Males
•  Only ______
are planted
Cycadophyta
•  Cycads
•  Palm-like plants
–  Sago Palms
•  Leaves in cluster
at top of trunks
Secondary
•  True __________
Growth
Gnetophyta
•  3 Genera
•  Ephedra
•  Mormon Tea
Ephedrine
–  ____________
•  raises heart rate
•  raises blood
pressure
Coniferophyta
Coniferophyta
•  Pine tree is the
sporophyte
generation
•  Contains both male
and female cones
–  Pollen (___________)
Staminate
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
Wings
– __________
for dispersal
Pine Life Cycle
•  Ovule in a ovulate cone
– integument (seed coat) (2n)
– megasporangia or nucellus (nutrition)
(2n)
Megaspores
– 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
generative cell
– 1 ___________
» produces 2 sperm
– 1 tube cell
Angiosperm Life Cycle
•  Ovule in Ovary
– megasporangia
– produces 4 megaspores (3 die)
• remaining one develops into female
Embryo sac
gametophyte called the _____________
Angiosperm Life Cycle
•  Embryo sac (Female
Gametophyte) consists of:
– 7 cells (eight nuclei) due to 3 mitotic
divisions
• 3
• 2
• 2
• 1
Antipodals
___________
polar nuclei (one cell)
Synergids
__________
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
•  Most flowers do not self-pollinate
– stamen and carpal may develop at
different times
– stamen and carpal may be arranged
in flower to avoid contact
Angiosperm Radiation
•  Begins the Cenozoic era (65 mya)
•  Most closely related to the
Gnetophyta
Coevolution
•  __________
– the mutual influence of two species
on each other
– plants and animals (insects, birds,
bats)