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Seed Plants

Gymnosperms & Angiosperms

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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Seed Dispersal

• Seeds may have adaptations such as stickers, hooks, or fuzz to adhere to animals

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Seed Dispersal

• Both water and wind can scatter seeds

Wind Dispersal

Water Dispersal

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Seed Dispersal Methods

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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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Monocot vs. dicot

• Number of cotyledons: one vs. two

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Monocot vs. dicot

• Leaf venation pattern:

• Monocot is parallel

• Dicot is net pattern

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Monocot vs. dicot root

• Monocot: Fibrous root

• Dicot: Tap root

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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)

Modified from cmassengale 25