The Plant Kingdom

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The Plant Kingdom
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Key Features

• Multicellular
• Photosynthetic
• Alternation of generations- All plants have a
  haploid-diploid life cycle in which haploid
  gametophytes alternate with diploid sporophytes

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Haploid/Diploid

• Haploid- a cell with 1 set of chromosomes. Often
  designated as n
• Diploid- a cell with 2 sets of chromosomes.
  Often designated as 2n

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Mitosis/Meiosis

• Mitosis- Cell division that produces 2 daughter
  cells that are identical to each other and to
  their parent cell. Occurs in both haploid and
  diploid cells
• Meiosis- Cell division of a diploid cell that
  produces four haploid daughter cells, or gametes

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Gametophyte/Sporophyte

• phyte means plant
• Anytime you have gamete as part of a word it
  refers to something that is haploid.
• Gametophyte is a plant that is haploid.
• Sporophyte is a plant that is diploid.

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Must Know Terms

• Sporangium- plant organ that makes the haploid
  spores
• Gametangium- plant organ that makes the haploid
  gametes
• Archegonium- female gametangia (makes eggs)
• Antheridium- male gametangia (makes sperm)

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Must Know Terms

• Homosporus- spores the resulting gametophytes
  identical (characteristic of non-vascular plants)
• Heterosporus spores and resulting gametophytes
  not identical (characteristic of vascular plants
• Megaspore- spore of the female gametophyte
• Microspore- spore of the male gametophyte

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Alternation of Generations

• The diploid generation is known as the sporophyte
• Certain cells of the sporophtye undergo meiosis
  to produce haploid spores
• These spores germinate, then divide by mitosis
  and develop into multicellular, haploid plants
  called gametophytes
• The gametophyte produces male and female haploid
  gametes by mitosis
• The gametes fuse to form a diploid zygote, which
  will develop into a diploid sporophyte

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Plant Origins

• Thought that a member of Chlorophyta gave rise to
  land plants
• Evidence that is thought to support this is

1. Green algae and plants have similar
chlorophyll 2. Green algae and plants store food
as starch and have cellulose in their cell
walls. 3. DNA comparisons have shown that green
algae are plants closest living relative.
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Transition to Land

• Plants are thought to have made the transition to
  land 400 mya
• They were able to invade land because the
  evolution of their conducting tissues, cuticle,
  stomata, and seeds made them progressively less
  dependent on external water for reproduction

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Transition to Land

• Need to note that the fossil record does not
  indicate which member of the kingdom Chlorophyta
  evolved into plants, nor does the fossil record
  indicate how or in which order green algae
  evolved the previously mentioned structures.

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Major Plant Divisions

• Nonvascular
• Vascular seedless
• Vascular seed plants

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Nonvascular

• Nonvascular plants are commonly grouped together
  as Bryophytes. In actuality, there are 3
  Divisions of nonvascular plants.
• Hepaticophyta- the liverworts
• Anthocerophyta- the hornworts
• Bryophtya- the mosses

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Primary Characteristics

• Gametophyte is green, manufactures own food
• Gametophyte large and conspicuous (compared to
  sporophtye)
• Sporophyte smaller than and derives food from
  gametophyte
• Sporophyte may be completely enclosed in
  gametophytic tissue
• Lack vascular tissue

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Primary Characteristics

• May or may not have distinct leaves and stems
• No anatomical differentiation between roots and
  shoots
• Possess colorless, non-absorptive, anchoring
  rhizoids
• The do not have lignin. Size is therefore
  limited.
• All are homosporous

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Ecology

• Common in temperate and tropical moist habitats
• Most abundant plants in Arctic and Antarctic,
  rare in deserts
• Require free water for growth and reproduction
• Sensitive to pollutants

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Hepaticophyta

• Liverworts
• Some have liver-shaped gametophyte that grows
  flat on the ground (thallose), some are leafy
• Some have moss-like growth form
• Sporophytes are generally unstalked and held
  within the gametophyte

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Anthocerophyta

• Hornworts
• Gametophytes resemble those of liver-shaped
  liverworts
• Sporophytes are elongate, erect sporangia that
  resemble horns

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Bryophyta

• Mosses
• Gametophytes are always leafy, tufted, or
  creeping
• Small, simple leaves spirally arranged on stem
• Sporophytes yellowish at maturity and bear
  capsule near the tip

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Moss Life Cycle

• The plant that we are most familiar with is the
  haploid gametophyte.
• The gametophyte forms haploid gametes through
  mitosis
• The sperm swims through a film of water (remember
  the need for free water) and fertilizes the egg,
  forming a diploid zygote which is retained in the
  archegonium

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Moss Life Cycle

• The zygote develops through mitosis into a small
  sporophyte that remains attached to the
  gametophyte
• The sporophyte produces haploid spores by meiosis
• The spores are released and may germinate to
  become a gametophyte.

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Differences

• Hornworts resemble thallose liverworts.
  Difference is determined by sporophyte

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Differences

• Mosses always have a stem and leaves, not all
  liverworts do
• Liverwort leaves are all in one plane, mosses
  leaves are arranges radially around the stem
• The capsules and seta (stalk) of mosses are
  green, red, or brown depending on age. Capsules
  of liverworts are dark brown to black and oval.
  Seta are transparent to clear.

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Differences

• Leaves of mosses may have serrations, hairs, or a
  midrib that goes to the tip. They do not have
  large indentations. Leaves of liverworts never
  have a midrib and often are lobed.

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Vascular Plants

• In the vascular plants, specialized groups of
  conducting cells (called vessels) impregnated
  with the stiffening substance lignin, serve both
  supportive and conducting features.
• Large, dominant, nutritionally independent
  sporophytes
• Specialized leaves, stems, roots, cuticles and
  stoma

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Vascular Plants

• Heterospory- a plant regularly forms two
  different kinds of spores, one of which gives
  rise to to egg-producing gametophytes, and the
  other of which gives rise to sperm-producing
  gametophytes
• Secondary growth- primary growth is cell division
  at the tips of stems and roots. Secondary growth
  results from the division of a cylinder of cells
  around the periphery, increasing diameter

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Conducting Systems

• Sieve elements- soft walled phloem cells carry
  carbohydrates away from area where they were
  manufactured
• Tracheary elements- hard walled xylem cells that
  transport water and minerals up from the roots

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Seedless Vascular Plants

• There are four living divisions
• Pterophyta- ferns
• Psilophyta- whisk ferns
• Lycophyta- club mosses
• Sphenophyta- horsetails

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Pterophyta

• Ferns
• Nearly all are homosporous
• Sporophyte generation is dominant
• Spores are produced in sporangia called sori
• Have specialized leaves, roots, and vascular
  tissue

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Fern Life Cycle

• Gametophytes are green and resemble liverwort
  gametophytes
• Archegonia (eggs) form on lower surface near the
  apical notch (see page 671)
• Antheridia (sperm) form on lower surface near the
  tip
• Mature sperm swim to archegonia to produce the
  zygote (requires free water)

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Fern Life Cycle

• Zygote develops into the sporophyte
• Is nutritionally independent, typical fern form
• Possess horizontal stem called a rhizome. True
  roots develop off the rhizome
• Photosynthetic fronds arise from the rhizome

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Fern Life Cycle

• Coiled bud stage of fronds is called a
  fiddlehead
• Sporangia develop on fronds
• Meiosis produces haploid spores
• Spores are released and form gametophytes

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Psilophyta

• Whisk Ferns
• Two living genera
• Vascular structure the same throughout the plant
• No true leaves
• Dichotomous branching in the stems
• Sporangia form on stems
• Homosporous

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Lycophyta

• Club Mosses
• Have both homosporous and heterosporous members
• Can resemble bryophytes, but sporophyte is the
  dominant generation
• Sporangia may be either along the stem or
  clustered in cone-like structures at the tips of
  branches

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Sphenophyta

• Horsetails
• Have jointed stems with scale-like leaves
• One living genus Equisetum
• Homosporous
• Sporangia clustered at the tips of some stems
• Life history is similar to other homosporous
  vascular plants

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Seed Plants/ The spermopsida

• Homework Read Chapter 22/ Take notes
• In Class Read pages 467-470 and answer these
  questions in complete sentences
• 1. What are three adaptations of seed plants that
  enable them to live on land
• 2. What are the functions of roots, stems, and
  leaves?
• How are xylem and phloem tissues similar? How are
  they different?

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Seed Plants

• Five divisions of seed plants
• Four of the divisions, Coniferophyta,
  Cycadophyta, Ginkophyta, and Gnetophyta are
  gymnosperms
• One of the divisions, Anthophyta, is made up of
  angiosperms (flowering plants)

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Seed Plants

• Gametophyte is greatly reduced in size
• The male gametophyte is the pollen grain and the
  female gametophyte is a small group of haploid
  cells in the ovule
• In bryophytes, the gametophyte is the dominant
  stage
• In seedless vascular plants, the gametophyte is
  reduced but free living and independent of the
  sporophyte

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Seed Plants

• Male and female gametophytes develop within the
  sporophyte
• Immature male gametophytes are called pollen
  grains
• Pollen is carried to female gametophyte during
  pollination
• The pollen germinates and forms a pollen tube
  that contains sperm cells
• Free water is not required for fertilization

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Seeds

• Consist of an embryonic plant, a supply of food
  for the embryo, and a protective outer coat
• The seed coat protects the embryo and keeps it in
  a state of dormancy
• The stored food helps sustain the emerging plant
• The can also help to enhance dispersal

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Gymnosperms

• Include conifers, cycads, ginkos, and gnetophytes
• Gymnos means naked. Sperma means seed
• At the time of pollination, the ovules
  (structures that contain the female gametophytes)
  are not completely enclosed by sporophytic tissue

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Images
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Coniferophyta

• Includes pines, firs, spruce, hemlocks, and
  cypresses
• Most abundant in the cold latitudes of the north
  and at high elevations where conditions are
  somewhat dry
• Evergreen leaves allow continual photosynthesis
• Needle-like leaves covered by thick cuticle
  minimizing evaporation

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Coniferophyta

• Each female cone consists of a series of woody
  scales arranged in a spiral around a central axis
• At the base of each scale are two ovules
• In each ovule, diploid cells undergo meiosis to
  produce haploid female gametophytes
• The female gametophytes develop and produce
  female gametes (eggs)

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Coniferophyta

• Once a pollen grain lands in a female cone near
  an egg cell, it makes a pollen tube that slowly
  burrows into the female gametophyte
• The cone scales grow together to protect the
  ovules
• The pollen tube becomes six celled, two of which
  are sperm

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Coniferophyta

• Once the pollen tube reaches the egg cell (about
  14 months) the sperm are released and the egg
  cell is fertilized
• The fertilized egg becomes enclosed in a seed as
  it develops into an embryonic plant

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• Gymnosperm gametophytes

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Vocabulary Check

• Sporophyte
• Gametophyte
• Plants that are homosporous
• Plants that are heterosporous
• Megasporangia (2n)
• Megaspores
• Megagametophytes
• Archagonia

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Vocab Check

• Sporophyte- diploid- gives rise to haploid spores
  as a result of meiosis
• Gametophyte- haploid- gives rise to gametes as a
  result of mitosis
• Plants that are homosporous produce only one kind
  of spore. Remember that sporophytes produce
  spores and spores grow into gametophytes.

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Vocab Check

• Plants that are heterosporous form two different
  kinds of spores.
• Megasporangia (2n) are the structures that form
  megaspores (n). Megaspores develop into
  megagametophytes (n). Megagametophytes form
  archegonia (n). Archegonia are where eggs (n)
  are formed.

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Vocab Check

• Microsporangia (2n) are the structures that form
  microspores (n). Microspores develop into
  microgametophytes (n). Microgametophytes
  (pollen) form antheridia (n). Antheridia are
  where sperm (n) are formed.

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http//videos.howstuffworks.com/hsw/10427-the-worl
d-of-plants-plants-that-make-seeds-video.htm
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Angiosperms

• One division called Anthophyta
• A flower is a structure in which both male and
  female gametophytes are formed
• Includes most of the plants you are familiar
  with. All deciduous trees, crop plants, grasses,
  flowers
• Ovules are enclosed within the tissue of the
  parent sporophyte in structures called carpels.

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Angiosperms

• The Angiosperm life cycle is similar to the
  conifer life cycle
• Male gametophytes (pollen) form inside anthers
• Female gametophytes develop within an ovule which
  is found in an ovary
• A pollen rain lands on the stigma and bores into
  an ovule
• The fertilized egg is enclosed in a seed

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Gynoecium

• Innermost whorl
• Composed of carpel(s)
• Stigma separated form body of carpel by the style
• Lower portion called an ovary
• More than one carpel may be present
• Traditionally called pistil(s) but carpel(s)
  is most correct

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Androecium

• Next outermost whorl
• Made up of stamens
• Stamens consist of a filament plus an anther
• Microspores are produced within the anther, shed
  as pollen
• Mature microgametophytes have three cells, two
  are sperm

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Perianth

• Two outermost whorls
• Corolla is composed of petals
• Calyx composed of sepals

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Megagametophyte

• Four cells develop from megaspore, three
  disintegrate
• Meiosis occurs within nucellus which is enfolded
  by integuments
• Ovule integuments nucellus
• Check out figure 33-24 and bold words on page 679

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Megagametophyte

• Mature megagametophyte called and embryo sac
• Produced from division of a megaspore
• Generally results in eight haploid nuclei
• Composed of seven cells, central cell has two
  polar nuclei

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Double Fertilization

• Recall that a mature microgametophyte has two
  sperm
• First sperm fertilizes the egg forming a zygote
• Second sperm fertilizes the cell containing the
  two polar nuclei
• The result is a triploid cell that develops into
  the endosperm. This is the initial nutrition
  source for the developing embryo

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