Plants

1
Plants

• Starr/Taggarts
• Biology
• The Unity and Diversity of Life

2
Key Concepts

• The plant kingdom consists mostly of multicelled
  photoautotrophs
• Almost all plants live on land
• Plants have structural adaptations that allow
  them to photosynthesize, absorb water and ions,
  and conserve water
• Land plants are reproductively adapted to
  withstand dry periods
• Seed producers were more successful in radiating
  into drier environments based on an evolutionary
  scale
• Gymnosperms and angiosperms are vascular plants
• Angiosperms include two classes of flowering
  plants
• Dicots and Monocots

3
Evolutionary Trends Among Plants

• Photoautotraphs
• Non-vascular plants
• Bryophytes
• Liverworts
• Hornworts
• Mosses
• Vascular plants
• Roots, stems, leaves

• Gymnosperms
• Seed bearing
• Gingko
• Cycads
• Conifers
• Angiosperms
• Flowers and seeds
• Dicots and Monocots

4
Evolution of Roots, Stems, and Leaves

• Water conservation
• Cuticle
• Stomata
• Roots and Stems
• Below ground

• Shoot systems
• Stems and leaves
• Sunlight and CO2
• Support of cell wall
• Lignin
• Vascular tissue
• Xylem
• Phloem

5
Evolutionary Trend Among Plants
6
Evolution of Pollen and Seeds

• Homospory
• Heterospory
• Pollen grains
• Sperm-bearing gametophytes
• Female gametophytes
• Spread by air, insects, birds
• Seeds
• Embryo of gametophytes
• Nutritive tissues
• Protective coat

7
Bryophytes

• Mosses
• Liverworts
• Hornworts
• Nonvascular
• Moist habitats mostly
• Small
• lt 20 cm tall
• Simplest plants

8
Moss Life Cycle
9
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

10
Life Cycle of a Fern
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The Rise of the Seed-Bearing Plants

• Seed ferns, gymnosperms, angiosperms
• Pollen grains
• Male gametophytes
• Ovules
• Egg producing gametophytes
• Pollination
• Pollen grains arrive on female reproductive
  structures
• Independent of water for fertilization

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Seed-Bearing Plants

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

13
Gymnosperms- Plants with Naked Seeds

• Conifers, Cycads, Ginkgos, Gnetophytes
• Conifers - cones
• Pines, cypress, firs, spruces, redwoods

14
Lesser Known Gymnosperms

• Cycads
• Tropical Subtropical areas
• Largest seed-bearing cones
• Zamia in Florida
• Gingko
• Gingko biloba
• Diverse in dinosaur times

• Gnetophytes
• Gneton
• Tropics
• Ephedra
• California
• Welwitschia mirabilis
• Deserts in Africa

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AngiospermsThe Flowering Seed-Bearing Plants

• Flowers
• Coevolution with pollinators
• Insects Bats Birds
• Seed
• Ovary

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Dicots and Monocots

• Almost 180,000 Dicots are herbaceous
• Cabbage and Daisies
• Flowering shrubs and trees
• Water lilies
• Cacti
• About 80,000 Monocots
• Orchids, palms, grasses, crop plants, rice

17
Pulling it Together

• Plants probably arose from green algae
• Trends in evolution can be identified by
  comparing structural adaptations to dry
  conditions, shifts to diploid dominance, and the
  shift to heterospory
• Bryophytes are nonvascular plants and require
  free water for fertilization
• Vascular plants are adapted to life on land
• Gymnosperms are vascular plants that produce
  pollen grains and seeds
• Ovules contain the egg-producing female
  gametophytes
• Evolution of pollen grains freed these plants
  from dependence on water for fertilization
• Angiosperms produce flowers and coevolved with
  pollinators