Chapter 25 Plants

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Chapter 25Plants

• Brandon Kraft,
• Carly Miller,
• and Nick Rego

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Evolutionary Trends Among Plants

• Photoautotrophs-organisms that get energy from
  sun and CO2
• Vascular plants
• Account for most plants
• Roots, stems, leaves
• Three Types
• Seedless Vascular Plants
• Cycads, lycophytes, ferns
• Seed-Bearing Vascular Plants
• Gymnosperms
• Angiosperms

• Non-vascular plants
• Account for remainder of plants
• Bryophytes
• Liverworts
• Hornworts
• Mosses

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Evolution of Roots, Stems, and Leaves

• Roots
• Evolved for life on land
• Underground, absorbtive
• Shoot systems
• Stems and leaves
• Above Ground
• Absorb Sunlight and CO2
• Support of cell wall
• Evolved Lignin

• Vascular tissue- for transport of materials
• Xylem
• Phloem
• Water conservation- necessary because of air
  exposure (prevents dehydration
• Cuticle
• Stomata

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Evolution of Pollen and Seeds

• Heterospory
• Produce two types of spores
• Sperm-bearing gametophytes
• Female gametophytes
• Spread by air, insects, birds
• Seeds - contain embryo and sustinence

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Bryophytes

• Mosses(most common), liverworts, hornworts
  (nonvascular)
• 3 adaptive features
• 1. Above ground parts display a cuticle with
  numerous stomata
• 2. Cellular protective jacket surrounds the
  sperm-producing and egg-producing parts of the
  plant to prevent drying
• 3. The embryo sporophyte begins life inside the
  female gametophyte
• Branched, feathery patterns
• Reproduce w/ flagellated sperm, which require
  liquid water to reach and fertilize the eggs

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Moss Life Cycle
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Existing Seedless Vascular Plants

• Whisk ferns, Lycophytes, Horsetails, Ferns
• 3 Differences from Bryophytes
• Sporophyte not attached to a gametophyte
• Has vascular tissues
• Longer phase in life cycle
• Habitat
• Moist places
• Gametophytes lack vascular tissue
• Sperm needs water to reach egg

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Life Cycle of a Fern
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The Rise of the Seed-Bearing Plants

• 360 million years ago
• 3 differences from seedless vascular plants
• 1. Produce pollen grains-the sperm-bearing male
  gametophytes
• Microspores give rise to pollen grains
• Does not depend on H20
• 2. Also produce megaspores, which develop inside
  ovules-at maturity is a seed (consist of female
  gametophyte)
• 3. Have H20 conserving traits
• Thicker cuticles
• Stomata recessed below the leaf surface.

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Spore of A Lycophyte
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Seed-Bearing Plants

• Depend on
• Pollen grains
• Ovules that mature into seeds
• Tissue changes adapted to dry conditions

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Gymnosperms- Plants with Naked Seeds

• Have exposed seeds- gymnos means naked, sperma
  means seed
• Conifers - have cones
• Woody trees/shrubs with needlelike leaves
• Cones- clusters of modified leaves that surround
  the spore-producing structures
• Firs, yews, spruces, junipers, larches,
  cypresses, etc.

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Lesser Known Gymnosperms

• Cycads-have pollen-bearing and seed bearing cones
  that form on separate plants
• Tropical/Subtropical areas
• Largest seed-bearing cones
• Many vulnerable to extinction
• Gingko
• Gingko biloba - only survivor
• Diverse in dinosaur times
• Males are resistant to insects, disease, and air
  pollutants

• Gnetophytes-woody plants that have 3 types
• Tropics and arid areas
• Groups of existing gymnosperms include
  conifers, cycads, ginkgos, and gnetophytes, which
  bear their seeds on exposed surfaces of cones and
  other spore-producing structures.

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Conifers

• Gymnosperms that reproduce via Cone Structures
  (Pinecones)
• Conifers produce both male and female pinecones
• Male Pinecones
• Produce Microspores (Pollen grains) that drift
  into the air
• Female Pinecones
• Produce Megaspores (Female Gametophtes)
• Accept Pollen grains
• Pollen Grows into Ovule
• Fertilization Occurs months after pollination

• Slow Reproductive Rate
• Disadvantage
• Angiosperms reproduce faster and compete for
  resources
• Deforestation
• Vulnerable

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AngiospermsThe Flowering Seed-Bearing Plants

• Most Successful Plants
• Only plants that flower
• Angeion- Female reproductive part of flower
• Requires pollination
• Transfer of pollen from one plant to next
• Pollination Processes
• Airborne pollen
• Pollinators
• Insects, bats, birds
• Coevolution

Angiosperm diagram
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Dicots and Monocots

• Two Types
• Monocots and Dicots
• Monocots
• Monocotyledon-
• One cotyledon (seed leaf for storage of food) in
  seeds
• Floral parts in groups of threes
• Parallel veins in leaves
• Orchids, palms, lilies, grasses (most
  crops-wheat, corn, etc)

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Dicots

• Dicotyledon-
• Two cotyledons in seeds
• Floral parts in groups of four or five
• Net-veined leaves
• Most Herbaceous (non-wooden) plants
• Most flowering shrubs and trees
• Water Lilies, Cacti