Non-Vascular Plants and Ferns

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Non-Vascular Plants and Ferns
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Evolution of Land Plants

• Land plants evolved from green algae
• The green algae called charophyceans are the
  closest relatives of land plants
• Comparisons of both nuclear and chloroplast genes
• Point to charophyceans as the closest living
  relatives of land plants

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Origin and Diversification of Plants

• Fossil evidence indicates that plants were on
  land at least 475 million years ago
• Whatever the age of the first land plants those
  ancestral species gave rise to a vast diversity
  of modern plants

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Plant Evolution
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Bryophytes

• Life cycles of mosses and other bryophytes are
  dominated by the gametophyte stage
• Bryophytes are represented today by three phyla
  of small herbaceous (nonwoody) plants
• Liverworts, phylum Hepatophyta
• Hornworts, phylum Anthocerophyta
• Mosses, phylum Bryophyta

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Bryophytes
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Liverworts

• Have no true roots or shoots
• Non- vascular
• Require water to reproduce
• Have no or very little leaf structure
• Cannot live in sporophyte form

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Hornworts

• Free-floating aquatic plant, or land plant
• No vascular tissue
• No true leaves or roots
• Can live in both gametophyte and sporophyte forms

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Mosses

• Land plant
• Most have no vascular tissue
• Majority to life spent in gametophyte
• Need water to breed
• No leaves or roots
• Sporophytes are capsules on stalks

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Vascular Plants

• Vascular plants have two types of vascular tissue
• Xylem and phloem
• Xylem
• Conducts most of the water and minerals
• Includes dead cells called tracheids
• Phloem
• Distributes sugars, amino acids, and other
  organic products
• Consists of living cells

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Vascular Plants

• Vascular plants have roots
• Are organs that anchor vascular plants
• Enable vascular plants to absorb water and
  nutrients from the soil
• May have evolved from subterranean stems
• Vascular plants have leaves
• Leaves are organs that increase the surface area
  of vascular plants, thereby capturing more solar
  energy for photosynthesis

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Vascular Plants

• Two types of vascular plants seedless and
  seeded
• Seedless vascular plants form two phyla
• Lycophyta, including club mosses, spike mosses,
  and quillworts
• Pterophyta, including ferns, horsetails, and
  whisk ferns and their relatives
• Modern species of lycophytes are relics from a
  far more eminent past
• Are small herbaceous plants
• Ferns
• Are the most diverse seedless vascular plants

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Seedless Vascular Plants
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Ferns

• Like vascular plants but do not have seeds
• Common in shady areas, diverse in the tropics
• Have flagellated sperm that require water to
  reach the eggs

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Alternation of Generations

• The seed plant life cycle contains both haploid
  and diploid stages
• Diploid individuals are called sporophytes
• Haploid individuals are called gametophytes
• Does not happen in algae
• May have evolved as an adaptation to harsh
  environments
• Haploid cells divide into a cluster of cells
  before meiosis

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Alternation of Generations
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Dominant Gametophyte

• Mosses have a dominant gametophyte stage

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Dominant Sporophyte

• Most plants have a dominant sporophyte stage

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Seeded Vascular Plants

• Gymnosperms- conifers, cycads, and ginkgo
• Angiosperms- flowering plants