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Plant Evolution. Adaptations. Cuticle alternation of generations specialized tissues. Cuticle. Waxy coating on surfaces resists drying out stomata exist to allow necessary gas exchange . Alternation of generations.

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adaptations
Adaptations
  • Cuticle
  • alternation of generations
  • specialized tissues
cuticle
Cuticle
  • Waxy coating on surfaces
  • resists drying out
  • stomata exist to allow necessary gas exchange
alternation of generations
Alternation of generations
  • Plants live part of their life in a haploid stage and part in a diploid stage
  • haploid portion is called the gametophyte generation because it produces the reproductive cells
  • diploid portion called sporophyte generation because it produces spores
alternation continued
Alternation continued...
  • The gametophyte plant produces male and female sex organs (male and female gametangium)
  • eggs are fertilized by sperm to form a zygote
  • embryo development (seed) occurs within the female gametangium (see fig 23-1 on p 421, 23-5 on p 426 and 23-8 on p 430)
specialized tissues
Specialized tissues
  • Other than bryophytes all other plants have vascular tissues
  • xylem - conducts water and minerals
  • phloem - conducts food
bryophytes
Bryophytes
  • Only nonvascular plants (mosses, liverworts)
  • no ability to internally transport water and materials
  • require moist environment
  • live in colonies, has rhizoids to anchor it
  • important in soil formation
ferns
Ferns
  • Seedless, flowerless, vascular plants
  • have xylem and phloem
  • has alternation of generation, the common familiar leafy plant is the sporophyte generation
  • has a rhizome and leaves
ferns ii
Ferns II
  • Spore production occurs on places on the fronds, sporangia are formed in which meiosis occurs to form spores.
  • Spores are often born in clusters called sori
  • spores are released and if they germinate will grow into the gametophytes
  • method of fertilization is primitive like bryophytes
ferns10
Ferns
  • Whisk ferns - extinct, no roots, no leaves but did have vascular system above and below ground!
  • Horsetails - roots, rhizomes and vertical stems
heterospory
Heterospory
  • Homospory - one type of spore produced by bryophytes and many ferns
  • Heterospory - some ferns have two types of spores produced microspores (male gametophytes) and macrospores (female gametophytes)
  • the development of heterospory leads two the two most successful kinds of plants
gymnosperms
Gymnosperms
  • Vascular, seed bearing, flowerless plants
  • means “naked seed”
  • largest division is conifers - woody cone bearing gymnosperms
  • leaves are called needles
  • most have male and female parts on same plant. Reproductive parts in cone.
gymnosperm reproduction
Gymnosperm reproduction
  • Microspores and macrospores formed in separate cones
  • Male cones smaller than female, on lower branches
  • meiosis in male cone produces a male gametophyte, also called a pollen grain
  • carried by air current to female gametophyte
angiosperms
Angiosperms
  • Flowering, vascular plants
  • most successful plants
  • fertilization in flowering plants called double fertilization
  • 2 sperm involved - 1 fertilizes the egg, the other fuses with 2 cells in female gametophyte to form endosperm
2 classes of angiosperms
2 classes of Angiosperms
  • Monocots - mostly herbaceous, long, narrow leaves,
  • parallel veination,
  • flower parts occur in threes,
  • single cotyledon (embryonic leaf),
  • endosperm present in seed
  • vascular bundles scattered
2 classes of angiosperms16
2 classes of Angiosperms
  • Dicotyledons - herbaceous or woody,
  • leaves variable in shape,
  • netted veination,
  • flower parts occur in 4 and 5,
  • 2 cotyledons,
  • endosperm usually absent in mature seed
  • vascular bundles arranged in a circle
plant evolution17
Plant Evolution
  • Bryophytes - no roots, leaves or stems, no vascular system, simple reproduction relying on water, gametophyte (haploid) dominant generation
  • Ferns - first vascular system, rhizomes (horizontal stems), fronds, sporophyte (diploid) dominant generation
plant evolution18
Plant Evolution
  • Gymnosperms - first leaves (needles), vascular system, stems and roots, naked seeds
  • Angiosperms - vascular system more organized, leaves, ability to shed leaves, seed provided with nutritive tissues, flowers, more sophisticated reproductive methods