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Seed Plants
Gymnosperms &
Angiosperms
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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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Characteristics of Seed Plants
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Multicellular
Autotrophic
Reproduce by Seeds
Vascular tissue for
transport
• Heterosporous –
make female
megaspores & male
microspores
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Dandelion dispersing seeds
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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Gymnosperms and
Angiosperms
• 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
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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,
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ginkgo biloba
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
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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
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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,
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etc).
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)
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Modified from cmassengale
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