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Plant Interactions
with the
Environment
Plant Evolution:
How have plants adapted over time to
survive in different environments?
Bryophytes: Mosses
Have
cuticle & stomata, but no
true roots
Water is required for fertilization
Fertilization occurs with spores
Non- Seed Plants:
 Produce spores
 Can be vascular
or non-vascular, but
have no true roots
All
vascular have xylem and phloem
 Whisk ferns, horse tails, club and ferns
are vascular non-seeded
Horse Tails
Ferns
Seed Plants
 Gymnosperms and Angiosperms
 produce seeds
 more effective than spores
cones,
flowers, pollen and seeds
are adaptations that allow
fertilization without water
 all
are vascular
Use
xylem and Phloem
Gymnosperms

Angiosperms
Use pollen and cones

Use pollen and flowers
“naked seed” plants

These seeds develop
inside a fruit

Angiosperms are most
successful because of
the fruits and flowers
(Evolution)


Rely on wind for pollination

Examples include pines, firs,
spruces, junipers, cedars,
cypress, and redwoods.
Everyday Plant Adaptations

Phototropism – Plants move towards the
sunlight for more energy

Gravitropism – Plants grow towards gravity
for water

Selective Stomata Opening and Closing –
Plants Conserve Water
Biome Adaptations:
Rainforest

Slide shaped leaves allow water to run off to prevent fungal
infections

Stilt root systems allow for better anchorage in shallow soil

Large leaf size help plants trap sunlight so photosynthesis can
occur with little available sunlight
Biome Adaptations:
Tundra

Grow close to the ground for warmth

Shallow root systems to absorb limited available
water

Dark pigmented plants absorb more heat
Biome Adaptations:
Desert

Deep roots to access water stored underground

Few stomates to prevent water loss

Thick cuticle to prevent water loss
Plant Responses
 Tropisms-
response to external
stimuli
may be positive (toward the
stimuli)
negative (away from the stimuli)
respond
to hormones that cause
growth, fruiting, cell division,
and ripening
Types of Tropisms:
Gravitropism-
response to gravity (stems
and roots); (negative and positive)
Phototropism-
positive, plants grow toward
light
Thigmotropism-
response to pressure
(Venus flytrap)
Nastic
Movement- touch; vines attach to
wall
Ex - Venus Flytrap (decrease in turgor
pressure)

Hormones in Plants


Auxin

Stimulates stem growth

Causes plant to grow toward the light
Cytokinins


Gibberellins


Promotes seed and bud germination
Abscisic Acid


Affects root growth, stimulates cell division
Inhibits growth, closes stomata, seed dormancy
Ethylene

Promotes fruit ripening

Ripening will slow down in lower temperatures