Seed

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Seed Plants
12.3
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General Facts

• Over 250,000 species
• Have roots, stems, leaves, and vascular tissue
  (vessels)
• Have seeds the reproductive part of a plant
  that contains a plant embryo and stored food

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SEEDS

• Formed after fertilization
• 3 parts
• Young plant (sporophyte)
• Stored food
• Seed coat (protects)
• Cotyledon (seed leaves) these are the first
  leaves that appear when a plant grows

(FOOD)
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Seed Plant Advantages

• Young plant uses stored food
• Seeds can be spread by animals
• Animals spread seeds better than wind

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2 Main Groups of Seed Plants
Gymnosperms
Angiosperms
NO flowers or fruit (cones)
Have flowers and fruit
Tulips
Blue Spruce
Oak Tree
Rose Bush
Scotch Pine
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Gymnosperms

• No flowers
• Seeds not protected by a fruit
• Seeds usually protected by a cone
• Most have needle-like or scale-like leaves
• Most are evergreens

Cycads
Ginkgos
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4 Divisions of Gymnosperms
Fir
Spruce

• Conifers largest division (550)
• Conifer cone-bearing
• Firs, spruces, cedars, hemlocks, redwoods

Redwood
Cedar
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Cycads

• Common millions of years ago
• 140 species
• Grow in the tropics
• Seeds develop in cones

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Ginkgoes

• ONE species
• The Ginkgo tree
• Seeds are attached directly to the branches
• Seeds protected by a thick, fleshy seed coat

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Gnetophytes

• 70 species
• Usually shrubs
• Dry areas
• Most have seeds that develop in cones

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Male
Female
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Gymnosperm Life Cycle

• Male cones produce pollen (sperm)
• Female cones produce eggs
• Male female cones may be on the same plant
  together or on separate plants
• Pollen gets blown from male cones to sticky
  substances on female cones
• Pollination transfer of pollen from male parts
  to female parts of seed plants
• Sperm fertilizes egg ? seed develops
• Seeds released from cone ? new tree grows if
  conditions are right

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WOW !!!

• Giant Sequoia
• 275 feet tall
• Base diameter 36 feet
• Largest branch diameter 7 feet

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Tallest living organism

• The Dyerville Giant 372 Feet tall when it fell
  in 1991 (Coast Redwood)
• Tallest living tree the Stratosphere Giant at
  3695 in 2002 (Coast Redwood)
• Both found in Humboldt Redwoods State Park in
  California

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Oldest Living Thing?

• Bristlecone Pine Trees are the oldest living
  trees on Earth
• Found mainly in California
• Methuselah 4767 years old

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Angiosperms

• Vascular plants that produce flowers and fruits
• Fruit a ripened ovary where seeds are formed
  (protect seeds)
• All produce flowers
• 235,000 species
• Over 50 of all plants are in this division

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2 Classes of AngiospermsMonocots and Dicots
Monocots

• 1 seed leaf (cotyledon) a leaf inside a seed
• Flower parts in 3s
• Parallel veins on narrow leaves
• Cereal grains like rice, wheat, oats

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DICOTS

• 2 seed leaves
• Flower parts in 4s or 5s
• Net-like veins on broad leaves
• Oaks, maples, lettuce, apples

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PLANT HISTORY

• Conifer and cycad fossils are as old as 200
  million years
• Angiosperms are believed to be only 120 million
  years old

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Modern Day Uses

• GYMNOSPERMS
• Building materials pines and spruces make up
  the majority of 2x4s and other lumber
• ANGIOSPERMS
• Are the basis of most animals diets

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