22-4 & 22-5 Seed Plants
Jan 02, 2016
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”
• 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