Chapter 21 What is a Plant

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Chapter 21 What is a Plant

• Adapting to life on land

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Plants are.

• multicellular, eukaryotic, autotrophic
• have thick cell walls composed of cellulose
• Have a waxy waterproof covering called a cuticle
• Green algae were ancestors of first plants
• First fossils appeared 500 mya (simple, no
  leaves) psilophytes (see page 576)

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From aquatic to terrestrial.

• Need water conserving methods since no longer in
  body of water
• Need roots to absorb minerals
• Need layer to prevent water loss (cuticle)
• Need way to reproduce that does not rely on water
• Grow upward against wind, rain, and gravity, so
  need support

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Adaptations in plants

• Water conservation and preventing water loss
  cuticle
• Leaves (instead of whole plant) carry out
  photosynthesis -- specialization
• Development of tissues roots, stems, leaves
• Roots acquire water and nutrients through here,
  anchor plant in soil
• Transport stem and vascular tissues (xylem and
  phloem)
• Seeds for reproduction
• Stems/trunks for support of leaves

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Plant Diversity

• What are the categories of Plants that exist?

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Kingdom Plantae
Non-vascular Plants (Bryophytes) (no transport
tissues present)
Vascular Plants (Tracheophytes) (have vascular
tissue)
Seedless Plants
Seed Plants
Angiosperms
Gymnosperms
Dicots
Monocots
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Figure 22-7 The Diversity of Plants
Section 22-1
Cone-bearing plants760 species
Floweringplants235,000 species
Ferns andtheir relatives11,000 species
Mosses andtheir relatives15,600 species
Bryophytes
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Kingdom Plantae

• Bryophytes
• Phylum Hepatophyta liverworts
• Phylum Antherocerophyta hornworts
• Phylum Bryophyta mosses
• Tracheophytes
• Seedless
• Phylum Lycophyta club mosses
• Phylum Psilophyta whisk ferns
• Phylum Sphenophyta horsetails
• Phylum Pterophyta ferns
• Seed Gymnosperms
• Phylum Ginkophyta ginkgo
• Phylum Cycadophyta cycads
• Phylum Gnetophyta Gnetum, Welwitschia,
  Ephedra
• Phylum Coniferophyta conifers (evergreens)
• Seed Angiosperms

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Nonvascular Plants -- Bryophytes

• Simplest of plants
• Have no vascular (transport) tissues no true
  stems, leaves, or roots
• Stay small and close to ground need to be near
  water to survive (absorption and reproduction)
• Have alternation of generation present for
  reproduction sporophytes (produce spores) and
  gametophytes (produce gametes)
• Ex. Mosses, liverworts, hornworts

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The Structure of a Moss
Section 22-2
Rhizoid
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The Life Cycle of a Moss
Section 22-2
Haploid (N) Diploid (2N)
MEIOSIS
FERTILIZATION
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Figure 29.15 Bryophytes
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Figure 29.15x1 Hornwort
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Vascular Plants -- Tracheophytes

• Most commom and widespread of land plants
• Have true vascular tissues -- xylem and phloem
  -- that allow true organs to develop roots,
  stems, leaves
• Xylem carries water and minerals in a plant
• Phloem carries nutrients in a plant
• Two categories seedless and seed plants

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Seedless plants

• Ex. Ferns
• Since dont have seeds, need LOTS of water for
  fertilization USE SPORES TO REPRODUCE FOR
  MAJORITY OF LIFE gametes are used only for a
  short period of time
• Display alternation of generations part of time
  is asexual (uses spores), part is sexual (uses
  gametes)

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Figure 29.21 Pteridophytes club "moss" (top
left), whisk fern (top right), horsetail (bottom
left), fern (bottom right)
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Figure 29.23 The life cycle of a fern
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Figure 29.24b Fern sporophyll, a leaf
specialized for spore production
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Seed Plants Gymnosperms and Angiosperms

• Gymnosperms naked seed plants most ancient
  of seed plants produce cones with seeds inside
• Ex. Gnetophytes, cycads, ginkgoes, conifers
• Angiosperms covered seed plants (these produce
  flowers.then fruits that have the seeds inside
  fruits provide seed protection and better
  guarantees seed dispersal when eaten by animals)
• Ex. Roses, apple trees, squash, azaeleas,
  grasses

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The Structure of a Seed
Section 22-4
B
Seed embryo of plant that is wrapped in a
protective covering and surrounded by a food
supply.
A
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Presence of a seed allows for reproduction
free of water.
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Figure 30.16 Fruit adaptations that enhance seed
dispersal Red berries (left), dandelion (right)
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Figure 30.5c Phylum Ginkgophyta Ginkgo biloba
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Figure 30.6 Phylum Cycadophyta cycads
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Figure 30.7a Phylum Gnetophyta Welwitschia
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Figure 30.8a Phylum Coniferophyta Douglas fir
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Figure 30.8x1 Bristlecone Pine
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Figure 30.8x2 Frasier fir
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Figure 30.10 A closer look at pine cones (Pinus
sp.)
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Figure 30.11 Representatives of major angiosperm
clades
Angiosperms
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Figure 35.2 Morphology of a flowering plant an
overview
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Parts of a flower
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Figure 30.13a The structure of a flower
Female parts
Male parts
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Figure 38.3ax1 Lily
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Figure 38.12 Development of a pea fruit (pod)
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Angiosperms

• Groups 1. Monocots and Dicots
• 2. Woody and Herbaceous plants
• 3. Annuals, Biennials, Perennials
• Groups based on
• 1. number of seed leaves in embryo
• 2. characteristics of their stems
• 3. lifespan of plants

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Comparison ofMonocots and Dicots
Section 22-5
Monocots
Dicots
Seeds
Leaves
Flowers
Stems
Roots
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Stem types
Herbaceous
Woody
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Concept Map
Section 22-5
Plants
are categorized as
that completetheir life cycle in
that completetheir life cycle in
that completetheir life cycle in
Go to Section
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Figure 38.1 Simplified overview of angiosperm
life cycle