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25-3 Plant Adaptations
Davis Blass
Ralph Beishline
Tom Yeager
Brain Teaser
 Think about all the plants you have seen in
your lifetime.
 Consider the environment where they
thrive.
 How are certain plants adapted to a dry,
desert-like environment? An aquatic
environment? An environment with very
few nutrients in the soil?
 What other adaptation may plants have?
I. Aquatic Plants
A. Aquatic plants are able to
tolerate mud that is saturated
with water and nearly devoid of
oxygen Ex: water lilies
B. To take in sufficient oxygen,
many aquatic plants have tissues
with large air-filled spaces
through which oxygen can
diffuse
C. The reproductive adaptations of
aquatic plants include seeds that
float in water and delay
germination for long periods
D. Many aquatic plants grow
quickly after germination,
extending the growing shoot
above the water's surface
II. Salt-Tolerant Plants
A. When plant roots take in
dissolved minerals, a difference
in the concentration of water
molecules is created between
the root cells and the
surrounding soil
B. Concentration difference causes
water to enter the root cells by
osmosis
C. Roots of salt-tolerant plants are
adapted to salt concentrations
that would quickly destroy the
root hairs on most plants
D. The leaves of these plants have
specialized cells that pump salt
out of the plant tissues and onto
the leaf surfaces
Ex: mangrove
III. Desert Plants
A. Plants that live in a desert biome
are called xerophytes. In this
biome they need to be able to
tolerate conditions like strong
winds, daytime heat, sandy soil,
and infrequent rain. Ex. Cacti
B. Plant adaptations to combat
these conditions include extensive
root systems, reduced leaves, and
thick stems for water storage.
C. Roots- stretch a long distance
just beneath the soil or are
extremely deep reaching. Also
have many root hairs to quickly
absorb water
D. Leaves- “spines” smaller surface
area to reduce transpiration
E. Stems- photosynthetic, store
water. Swell during rainy periods,
and shrivel during dry spells
F. Seeds- can remain dormant for
years until sufficient moisture
guarantees a chance at survival.
Plants can mature, flower, and set
seed in weeks or even days,
before the water disappears.
IV. Nutritional Specialists
A. Grow in environments with low
concentrations of nutrients.
Include carnivorous plants and
parasites
B. Carnivorous Plants
1.Soil has little or no nitrogen
present because no bacteria can
survive to decay dead organisms.
2.Some plants have adaptations to
trap and digest insects.
Examples:
 Pitcher Plant- drown prey in pitchershaped leaves that hold rain water
and digestive enzymes
 Sundews-leaf hairs tipped with sticky
secretions
 Venus Fly Trap- hinged leaf blades.
Trap prey when folded.
C. Parasites
1. Extract water and nutrients directly
from host plant. They harm their
host and may pose a threat to other
organisms
Examples:
 Cuscuta- no chlorophyll to make food.
Grow directly into host’s vascular
tissue.
 Mistletoe- parasite of conifers in
Western U.S.
V. Epiphytes
Epiphytes are plants not rooted in soil
but grow on bodies of other plants,
not parasites because they get their
own water and make own food, live
mainly in rainforests but also in other
moist biomes
Ex: Spanish moss and most orchids
VI. Chemical Defenses
A. Many plants defend themselves
against insect attack by
manufacturing compounds that
have powerful effects on animals
Example: Foxgloves
 Effects: can be lethal if eaten,
disrupt normal growth and
development, prevent insects
from reproducing
 Human Uses: aspirin, codeine,
and other medicines
 Tobacco: chemical in tobacco is
called nicotine, affects human
nervous system, used to protect
plant from predators
 Evolution: some insects have
evolved to deal with poisons,
monarch caterpillar can eat
milkweed because it can store
the toxic compounds in its
body, makes it poisonous to
other animals