Transcript PLANTS!! - Woodstown-Pilesgrove Regional School District

PLANTS!!
Food, habitats, carbon dioxide taker uppers, oxygen
providers
What more could we ask for???
Kingdom: Plantae
• 280,000 species
• Ecological, industrial and medical importance
• Thought to evolve from green algae, 500 mya
• Both have chlorophyll a and b, store excess carbs, cellulose in cell
walls.
4 Evolutionary milestones
• Nonvascular plants that nourish a multicellular
embryo within the body of the female plant
(different from green algae)
• Vascular tissue specialized for transport (430
mya)
• Production of seeds (contains embryo and stored
nutrients within a protective coat) 400mya
• Flower –reproductive structure 135 mya
• See cladogram pg 415
Alternation of Generations
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2 multicellular individuals alternate, each produce the other
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Sporophyte – diploid generation
Gametophyte – haploid generation
Sporophyte generation (2n)
• Sporophyte – production of spores by meiosis
• Spore – haploid reproduction cell that develops a new organism
without fusing with another organism.
• Spores undergo mitosis and becomes a gametophyte
Gametophyte generation (n)
• Production of gametes
• Sperm and eggs are developed by mitosis
• fuse = diploid zygote
• Undergoes mitosis = sporophyte
Alternation of generations
• Meiosis produces haploid spores (gametophyte generation)
• Mitoisis occurs when
• Spore becomes a gametophyte
• Zygote becomes a sporophyte
Alternation of Generations
• In nonvascular plants – gametophyte is dominant
• Vascular seedless, naked seed and flowering plants –
sporophyte is dominant
• Adaptation to life on land
• Gameotphyte becomes microscopic
Adaptations to terrestrial life
• Water transport and conservation – vascular tissue
• Protection from desiccation – waxy cuticle, stomata
Nonvascular Plants
• No means of transporting water or organic
nutrients
• No true roots, stems or leaves, just root like…
• bryophyte – term for nonvascular plants
• Gametophyte is dominant generation, the part
of the plant we see.
• Females produce eggs in archegonia
• Males produce flagellated sperm in antheridia
• need film of water for sperm to meet egg
• Characteristics limits size of bryophytes
• 3 phyla, hornworts, liverworts, and mosses
Hornworts and liverworts
• Hornworts – most live in moist shaded areas
• Can reproduce asexually by fragmentation
• Horns are sporophyte that grow from gametophyte
• Liveworts – most terrestrial, some epiphytes
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Thallose – with a flattened thallus
Leafy – look like mosses
Lobes look like liver
Phizoids – extensions that anchor in soil
Mosses
• Gametophyte appear as leaflike structures
• Peat, true and rock mosses
• Prefer damp, shaded areas, can dry up and turn
brown, and be revived with rain
• Can reproduce asexually by fragmentation
• Moss life cycle figure 24.9
• Uses include
• sphagnum – ability to absorb water, used in gardening
• Peat – accumulated dead moss can be used as fuel and
bandages.
Vascular plants
• Xylem – conducts water and minerals up from the roots
• Walls of cells are strengthened by lignin
• Phloem – conducts sucrose and other organic compounds
down from point of photosynthesis
• Seedless vascular – homosporous (1 type)
• Seed plants – heterosporous (2 types, m/f), leads to evolution
of pollen grain and seed
Seedless vascular plants
• Sporophyte dominant
• Independent gametophyte, archegonium and antheridium,
still need water.
• Club mosses
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Ground pines, spike mosses and quillworts
Have 1 strand of vascular tissue
Rhizome – horizontal underground stem
Strobili (cones) – contain sporangia
Seedless vascular
Ferns and allies
• Horsetails
• Have rhizomes and stroboli
• Whisk ferns
• No leaves, sporangia are yellow, look like whisk broom
• Fern
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first fiddleheads that unrolls into fronds
Megaphylls (more than 1 vascular strand)
Dominant sporophyte produces windblown spores
Life cycle figure 24.16
Uses: decorative, building material, medicinal, expel
intestinal parasites
Seed plants
• Gymnosperms (naked seed) and angiosperms
(flowering plants)
• Contain sporophyte embryo and stored food
within a protective seed coat
• Allows survival during harsh conditions
• Heterosporous, 2 types of gametophytes (m/f)
• Pollen grains – male gametophyte
• Pollination – when pollen grain is brought to vicinity of
female gametophyte by wind/pollinator, no water
needed!
• Female gametophyte develops within an ovule which
eventually becomes a seed
Gymnosperms
• Conifers, cycads, ginkgoes and gnetophytes
• Ovules and seeds are exposed, not enclosed by fruit (naked
seed)
Conifers
• Conifers – evergreens, including pines, spruces, firs, cedars,
redwoods…bears cones
• Tallest – redwood, oldest – bristlecone pine
• Life cycle of pine fig. 24.18
• Used in construction, soft due to amount of xylem tissue,
resin (turpentine)
• Monoecious – tree produces both pollen and seed cones
Cycads
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Tropical, subtropical
Used in landscaping, resemble palms
Pollen and seed cones on separate plants
Pollinated by insects
Ginkgoes
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Maidenhair tree
1 species remains, Gingko biloba
Dioecious – some trees produce seeds, other pollen
Female seeds produce an odor, males preferred
Resistant to pollution
Seeds a delicacy
Extracts used medically
Gnetophytes
• Lack archegonia, like angiosperms, thought to be most closely
related
• Ephedra – shrub, ephedrine is extracted
Angiosperms
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Flowering plants
Provide clothing, food, medicines
Ovules are enclosed within diploid tissues
Dominance of angiosperms is related to evolution of flying
insects (pollination)
Monocots and Eudicots
• Cotyledon – seed leaf, contains nutrients that nourish the
plant embryo
• Monocots – corn, tulips, poineapple, bamboo
• Eudicot – cactuses, strawberries, dandelions
The Flower
• Common structures in all flowers
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Peduncle – flower stalk
Receptacle – expanded tip, contains the following:
Sepals – (calyx) – protect the flower bud before opening
Petals – (corolla) – differ in color, shape and size
Stamens – consists of anther (produce pollen grains) and filament
Carpels – stigma (sticky knob), style (stalk) and ovary (enlarged
base that encloses ovule)
Flowering plant life cycle
• Megaspores – in ovule within ovary of carpel, develops into
egg bearing female gametophyte embryo sac
• Microspore – produced in anthers, pollen grains, develop into
sperm bearing male gametophytes
• Fruit – derived from an ovary
Diversificaiton
• Wind pollinated – usually bland
• Insect/bird pollinated – usually colorful
• Night blooming flowers – aromatic and white
• Fruits protect and aid in dispersal of seeds