Seeds on the Move Enrichment LESSON 3

Name
Date
Enrichment
Class
LESSON 3
Seeds on the Move
The one time in the lives of most plants
that they will move any significant
distance is during the seed stage. Seeds are
more likely to grow when they travel away
from the parent plant. Over time, plants
and seeds have developed adaptations that
help seeds move. There are several different
strategies for seed dispersal.
than pollen grains, so they need a little
assistance to stay airborne until a breeze
takes them aloft. One adaptation for seed
flight is wings. These are not wings that
flap, but gossamer structures that fan out
from the seed, designed to catch the wind.
The seeds of a red maple are perfectly
shaped to cause seeds to spin like tiny
helicopters as they drop to catch the wind.
Animal Food
Animals that eat fleshy fruits usually
swallow the seeds, too. A swallowed seed
travels through the digestive system and is
deposited, covered in fertilizer. An example
of this type of seed dispersal is when a bird
has eaten blackberries.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Hitching a Ride
Some seeds have outer coats that are
hard, abrasive, or heavily barbed with
hooks on the end of sharp spines. These
seeds readily snag onto a passing animal’s
fur or person’s clothing. Animals often
become irritated when there are too many
burrs stuck to them. When you see deer
rubbing against trees or wallowing in the
dirt, they are probably trying to dislodge
sticky seeds, such as burdock and
cockleburs.
Wind and Flight Plans
Like pollen, some seeds are carried by
wind. Seeds are generally larger and heavier
Explosions and Shakers
Some plants produce seeds in pods that
develop tensions throughout the pod as the
seeds develop. All it takes is a nudge from
an insect, a breeze, or the brush of an
animal to make the pod crack open and
fling seeds in many directions. Peas and
touch-me-nots do this. Other seeds like
poppies develop in a hard pod with tiny
holes. As the wind shakes the pod, the
seeds fall like pepper from a shaker.
Drop and Roll or Float
Many seeds are too large to fly on the
wind, or they are not tasty. Some seeds are
too high in the plant for animals to reach.
When a horse chestnut drops, for example,
its case might crack open, allowing the seed
to roll away from the plant. Some seeds
such as coconuts and mangrove seeds can
drop into or near water, and they float
away with the tide.
Applying Critical-Thinking Skills
Directions: Respond to each statement.
1. Name three mechanisms of seed dispersal.
2. Describe how the dispersal of seeds by animals is a mutually beneficial relationship.
3. Assess the benefits of seeds traveling away from the parent plant.
Plant Processes and Reproduction
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