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