Quick Defs…
• Vascular = xylem and phloem – Xylem = Brings water/nutrients from
roots to the plant.
– Phloem = Brings sugars down from the leaves
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Evolution Of Land Plants REMEMBER: • Terrestrial plants evolved from a green algal ancestor
• The earliest land plants were nonvascular, spore producers (bryophytes)
• Ferns were the 1st vascular, spore producing plants
• Gymnosperms & angiosperms were the 1st vascular, seed plants
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• Multicellular
• Autotrophic
• Reproduce by Seeds
• Vascular tissue for transport
• Heterosporous – make female megaspores & male microspores
Characteristics of Seed Plants
Dandelion dispersing seeds
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Reasons for Success on Land
• Waxy cuticle
• Stomata with guard cells to open & close
• Seeds protect developing embryo & contain food
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Seeds
• Seeds contain a young, developing plant embryo
• Seeds are covered with a protective seed coat (testa)
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Seed Dispersal
• Seeds must be scattered (dispersed) away from the parent plant
• Testa (seed coats) may last thousands of years
• Seeds eaten by animals aren’t digested but pass out with wastes
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• Gymnosperm – Intro and evolution – Life cycle and
reproduction – Uses and significance
• Angiosperms: Flowering plants – Intro and evolution – Life cycle and
reproduction – Uses and significance – Monocots vs. dicots
Gymnosperms and Angiosperms
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GYMNOSPERMS • Introduction – Gymnosperm means “naked
seed” (From the Greek: gymnos = naked;
sperm = seed)
• More advanced than ferns – do not have spores, they have seeds.
• The seeds of the gymnosperms lack a protective enclosure (unlike flowering plants which have flowers and fruit).
• Examples of gymnosperms:
• Conifers (pine trees), cycads, ginkgo biloba
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Conifers • Conifers adapted to temperate to cold
regions
• Narrow leaves (needles) help to conserve water
• Covered by resins – for protection from predators, fire, etc.
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Other gymnosperms
• Cycads – short shrubs, native to tropical regions (look like palms)
• Ginkgo biloba – a “living fossil”, male and female tree, used as a medicinal plant
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Significance of gymnosperms • Ecological importance:
• Provide food and habitat for wildlife
• Forests prevent soil erosion
• Reduce greenhouse-effect gasses
• Economic and commercial importance:
• Lumber for wood, paper, etc.
• Resins – wood, furniture, etc.
• Ornamental plants (trees, landscaping)
• Food – pine nuts (pesto, etc.)
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ANGIOSPERMS
• Angiosperm means “covered seed”
• Have flowers
• Have fruits with seeds
• Live everywhere – dominant plants in the world
• 260,000 species (88% of Plant Kingdom)
• Angiosperms are the most successful and advanced plants on earth
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Evolution of Angiosperms • Advancements over gymnosperms:
• Angiosperms have flowers – many use pollinators
• Fruits and seeds – adapted for dispersal
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Monocot vs. dicot
• Angiosperms are divided into monocots and dicots
• As the zygote grows into the embryo, the first leaves of the young sporophyte develop and are called as cotyledons (seed leaves)
• Monocots have one cotyledon (corn, lily, etc).
• Dicots have two cotyledons (bean, oak, etc).
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Reproduction of Angiosperms: * Pollination = Pollen falls on a stigma when wind, bees, or bats carry it. (Sugar-rich nectar in the flower attracts bees or bats.) * Fertilization = sperm & egg join together in the flower’s ovule. - The zygote develops into the embryo part of the seed. - The ovary around the seed develops into a fruit. (Apples, cherries, tomatoes, squash, etc. are all fruit.) * Dispersal – animals eat the fruit and the seeds come out the other end.
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Life Spans of Angiosperms: * Annuals = complete a life cycle in one year. (pansies, wheat, tomatoes, cucumbers, etc) * Biennials = complete life cycle in two years. (Second year they produce flowers and seeds.) (Parsley, celery, etc) * Perennials = live for more than two years (Oak tree, honeysuckles, etc) (Roots and stems survive the winter)