Plants and the Colorization of Land
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Transcript Plants and the Colorization of Land
Chapter 30:
Plant Diversity II:
The Evolution of Seed Plants
Seed Plants
Gymnosperms – naked seeds
Angiosperms – covered seeds
These two groups are the dominant plants
on Earth today.
Adaptations: Seed Plants
Gametophytes are even more reduced.
Seeds replaced spores as the means for
dispersal.
Pollen is the vehicle for sperm cells.
Life Cycle switch
Gymnosperms - Divisions
Coniferophyta - Conifers
Cycadophyta - Cycads
Ginkgophyta - Ginkgo
Gnetophyta - Gnetae
~700 species
Characteristics
Seeds with multiple seed leaves.
Cones (strobili).
Xylem with tracheids only.
No flowers or fruits.
Life Cycle
Most are heterosporous.
Male gametophyte = pollen grain.
Multi-cellular female gametophyte still
produces archegonia.
Conifers
Two types of cones
Pollen cone - male
Ovulate cone - female
Pollen Cone
Male Cones
Sporangia
Pollen Cone
Sporangia with
pollen
Male Gametophyte or Pollen
Pollination
Transfer of pollen from one individual to
another.
Usually accomplished by the wind for most
Gymnosperms.
Ovulate Cone
At time of Pollination
Ovulate Cone
Ovulate Cone
Megaspore
Mature Cones
Conifers Fertilization
Fusion of sperm and egg to produce a
zygote.
Pollination and fertilization may be separated
by 1 year.
Conifer Seeds
Embryo
Mature Seed
Importances
Coniferophyta:
Lumber
Paper
Resins
Importances
Food
Landscaping
Christmas trees
Other Examples
Cypress
Pacific Yew
Importances
Cycadophyta:
Landscaping
Food
Ginkgo
Ginkgophyta:
1 species extant
Living fossil
Ginkgo
Tree
Fall Color
Ginkgo - Male
Male cones
Sperm
Ginkgo - Female
Female cones
Mature cones
Importances
Landscaping
Drug
Seeds (?)
Importances
Gnetophyta:
"Mixed bag" of species
Various importances
Ephedra
Other Gnetophyta
Welwitschia
Gnetum
Angiosperms
Division - Anthophyta
Most dominant plant group on land.
Two main classes:
Monocotyledones (Monocots)
Dicotyledones (Dicots)
~235,000 species
Characteristics
Have seeds, flowers and fruits.
Characteristics
Xylem may have
vessels.
Life History
Male gametophyte reduced to a 2-3 celled
pollen grain.
Female gametophyte reduced to an embryo
sac.
Double fertilization.
Importances
Food
Lumber
Medicines
Landscaping
Fibers
Importances
Rubber
Flower Industry
Dyes
Spices
Soil Erosion Control
Angiosperms
Main group for study of plants in future
lessons.
Summary
Know the adaptations of seed plants.
Know examples, life cycles, and importances
of the gymnosperms and angiosperms.