Transcript Seed Plants

22-4 & 22-5 Seed Plants
Seed Plants
• Divided into two groups:
– Gymnosperms – have seeds directly on surfaces
of cones
– Angiosperms – have seeds within a layer of
tissue that protects the seeds
• Also called “flowering plants”
Seed Plants
• Why are they the most
dominant plants on land?
– Unlike bryophytes (mosses)
and ferns, seed plants don’t
require H2O to reproduce
– As a result, seed plants can
live just about anywhere,
wet or dry!
Seed Plants
• Adaptations that allow seed plants to
reproduce without water include:
– Protection of embryos in seeds
• Seed-containing structures: cones (gymnosperms)
and flowers (angiosperms)
– Transfer of sperm by pollination
The seed
• Seed – embryo of plant
encased in a protective
covering (seed coat) and
surrounded by a food
supply
Tough Seeds
• Seeds can survive long
periods of bitter cold,
extreme heat and even
drought by only
continuing to grow
when conditions are
more ideal
– example: Desert
Paintbrush (Castilleja
chromosa)
Pollination
• Pollen grain: entire male gametophyte
(sperm)
• Pollination: transfer of pollen from male sex
structure to female sex structure
– by water, wind, insects, or small animals
Gymnosperms – “naked seed”
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Produce seeds that are exposed
Cone-bearing plants
Oldest surviving seed plants
Include conifers (ex. pine trees),
cycads and ginkgoes
Angiosperms – “enclosed seed”
• Flower and fruit production are evolutionary advantage
• Flowers
– Attract pollinators
– Contain ovaries which surround/protect seeds
• Ovaries develop into fruit
• Fruit
– Protects the seeds
– Helps spread seeds (remember the “Seedy Side of
Seeds”?)
The 2 Classes of Angiosperms
• Monocots: embryo has one
seed leaf (cotyledon)
– Examples: corn, orchids and
palms
• Dicots: embryo has two
seed leaves (cotyledons)
– Examples: roses, tomatoes,
and oaks
• ** They have many
differences…
Monocot/Dicot Table
• Use same piece of paper you used for the
“Alternation of Generation” drawing
• In 2 squares underneath the “Alt. of Gen.”
drawing, you will draw figure 22-25 on
p.570 of “Biology” textbook
• Include: all headings for rows and columns,
all descriptions and color all drawings