 Notebook
 Pencil/pen
 Seed dispersal
Today we will
discuss the
mechanisms for
seed dispersal
No Gum Please!
 Bell
 Seed dispersal
 Brain pop/video
Daily Question: What
is one thing you
learned yesterday
about whale
Mechanisms of Seed Dispersal:
Animals, Wind, Water, & Other
Pacific Union College (2007). Pacific Union College. Retrieved January 23,
2007, from Botany Glossary Web site:
Mature Seed:
Consists of an embryo that is frequently
surrounded by a food reserve and a
protective coating.
Is capable of germinating under the proper
conditions and forming a mature plant.
D. Seeds. Retrieved January 23, 2007, from Dierdra's Home Page Web site:
Seed Dispersal:
Adaptive mechanism
of plants that ensures
seeds will be:
separated from the
parent plants.
distributed over as
large an area as
possible to ensure the
germination and
survival of some of the
seeds to adult plants.
Dispersal by Animals:
 Most flowering plants use animals to carry seeds. (1995). Retrieved January 26, 2007, from Microscopy-UK
Web site:
Dispersal by Animals cont’d
Some flowering
plants produce
edible fruits.
These juicy, tasty,
sweet, colorful
fruits often have
seeds that are
animal dispersed.
Toucan eating fruit from a tree.
(Jan 26,2007). Retrieved January 26, 2007, from Web site:
Dispersal by Animals cont’d
When the seeds of
the plant become
mature, the
surrounding fruit
becomes softer and
its sugar content
Some fruits become
fragrant and brightly
colored to advertise
their ripeness to
Ripened and unripened
banana fruits on banana tree
M. (April 16, 2004). Our Florida Garden. Retrieved January 26, 2007, from Welcome to
Mimi's HomePage Web site:
Dispersal by Animals cont’d
Interactions with
animals have
helped flowering
plants become
the most
plants on earth.
Brown capuchin monkey (Cebus apella)
snarling while eating fruit.
Butler, R. (2007). World Travel Photos. Retrieved January 26, 2007, from Tropical
Rainforest Conservation Web site:
Dispersal by Animals cont’d
Animals eat fruits and defecate:
When the animal ingests the fruit the
animal digests the fleshy part.
 The seed coat usually prevents the digestion
of the seeds.
Many such fruits contain laxatives to help
the process along.
The tough seeds usually pass unharmed
through the digestive tract.
The animal deposits the seeds, along
with a fertilizer supply, miles from the
parent plant where the fruit was eaten.
Seed dispersal by animal ingestion,
Blue Jay scat contains Rosa seeds and others
© Wally Eberhart / Visuals Unlimited
 Note: One of the most common colors of
fruits is red, a color insects cannot see
very well; therefore, most of the fruit is
saved for animals large enough to
disperse the seeds.
(May 17, 2002). Black Cherries. Retrieved January 26,
2007, from Seed Dispersal Web site:
Baskauf, S. (Jan. 22, 2007). Plant Features. Retrieved January 26, 2007, from
Bioimages Web site:
Seeds traveling on animals:
Some flowering plants have fruits modified
as burrs that cling to animal fur or the
clothes of humans.
Cocklebur seeds on fur,
seed dispersal
Cavagnaro, D. (2007). Cockleburr on Fur. Retrieved January
26, 2007, from Visuals Unlimited Stock Photography Web site:
Animals bury seeds
 Small animals collect seeds and bury
them as food stores for a later date when
food is scarcer. Occasionally, these
animals do not return to collect these
seeds, and they leave them planted in the
Animals bury seeds cont’d
Squirrels bury oak acorns and sometimes
forget where they buried them, thus
planting a tree far away from the parent
Animals bury seeds cont’d
 Blue Jays also bury acorns. They usually
remember where they bury them, but at
times they bury more than they need. This
leaves some acorns in the ground, which
may eventually sprout.
Wind Dispersal
 Small, hard, dry
fruits are often
dispersed by wind.
Some plants have
seeds within fruits
acting as kites or
propellers that aid
in wind dispersal.
Seed dispersal from the
Common Milkweed (Asclepias
syriaca), North America.
Leroy Simon / Visuals Unlimited
Wind Dispersal cont’d:
 Most of these plants
produce a large number
of seeds, but most of
the seeds will not
produce mature plants.
Their large number and
ability to disperse to
new habitats ensure
that at least some will
grow and eventually
produce seeds
Wind Dispersal cont’d:
Maple winged fruits
 Some plants
have seeds within
fruits acting as
kites or propellers
that aid in wind
Wind Dispersal cont’d
 The entire tumbleweed plant dries up and
is blown across fields and roads,
dispersing seeds as it tumbles.
Pine cones use wind and fire to disperse
their seeds:
After one to three years of maturing, the pine
cone opens up and the winged seeds travel
on the wind.
 Where natural
fires are common,
many seeds
require intense
heat to break
 Seedlings are
therefore most
abundant after fire
has cleared away
Ex: Pitch pine cone: during a fire the pitch
pine cones will open in extreme heat.
The process of
seed production for
pine trees to
Water Dispersal
Some small, hard, dry
fruits are also dispersed
by water. These plants
have seeds that float
and travel on the water
until washed up on
 Fruits such as the
large seeded pod of
the 'Black bean'
australe (below) float
well in water.
Water dispersal of seeds in the rainforest
Water Dispersal cont’d
• Some plants
produce a moderate
number of very large
seeds with a high
amount of nutrients,
which ensures the
survival of most of
the offspring.
Coconut Palm
Water Dispersal cont’d
 Box fruits, Barringtonia asiatica, are
widespread drift fruits in the tropical Pacific,
remaining buoyant for more than two years.
They are common in the turquoise-blue
waters of French Polynesia.
Popping Seeds
 Some seeds have evolved a popping
mechanism for short distance dispersal.
 As the seed matures, the pod or husk dries
out and may start to shrink around the seeds.
 After it shrinks so far, it may “pop” and
scatter the seeds around.
Touch-me-nots are aptly
named. The seed capsules
develop from mid summer
through fall. If touched,
picked or otherwise
disturbed, they rupture like
a broken spring; projecting
their seeds several feet.
Cockleburs stuck to
shoe and sock of hiker.
Forensic Science
Presentation developed by T. Trimpe 2006
Biology of Hair
Hair is composed of the protein keratin, which is also the primary component of
finger and toe nails.
Hair is produced from a structure called the hair follicle. Humans develop hair follicles
during fetal development, and no new follicles are produced after birth.
Hair color is mostly the result of pigments, which are chemical compounds that reflect
certain wavelengths of visible light.
Hair shape (round or oval) and texture (curly or straight) is influenced heavily by
genes. The physical appearance of hair can be affected by nutritional status and
intentional alteration (heat curling, perms, straightening, etc.).
The body area (head, arm, leg, back, etc.) from which a hair originated can be
determined by the sample’s length, shape, size, color, and other physical
In order to test hair evidence for DNA, the root must be present.
Sources: &
Hair Structure
Hair is composed of three principal parts:
Cuticle – outer coating composed of overlapping scales
Cortex – protein-rich structure around
the medulla that contains pigment
Medulla – central core
(may be absent)
The structure of hair has been compared to that of a pencil with the
medulla being the lead, the cortex being the wood and the cuticle
being the paint on the outside.
Hair Structure
The cuticle varies in:
• Its scales,
How many there are per centimeter,
How much they overlap,
Their overall shape, and
How much they protrude from the surface
• Its thickness, and
• Whether or not it contains pigment.
Characteristics of the cuticle may be important in distinguishing
between hairs of different species but are often not useful in
distinguishing between different people.
Hair Structure
The cortex varies in:
• Thickness
• Texture
• Color
• Distribution of the cortex is perhaps the most important component
in determining from which individual a human hair may have come.
• Microscopic examination can also reveal the condition and shape of
the root and tip.
Hair Structure
The medulla may vary in:
• Thickness
• Continuity - one continuous structure
or broken into pieces
• Opacity - how much light is able to
pass through it
• It may also be absent in some species.
Like the cuticle, the medulla can be important for
distinguishing between hairs of different species, but often
does not lend much important information to the
differentiation between hairs from different people.
Fiber Evidence
A fiber is the smallest unit of a textile material that has a length many times
greater than its diameter. A fiber can be spun with other fibers to form a yarn that
can be woven or knitted to form a fabric.
The type and length of fiber used, the type of spinning method, and the type of
fabric construction all affect the transfer of fibers and the significance of fiber
associations. This becomes very important when there is a possibility of fiber
transfer between a suspect and a victim during the commission of a crime.
Matching unique fibers on the clothing of a victim to fibers on a suspect’s clothing
can be very helpful to an investigation, whereas the matching of common fibers
such as white cotton or blue denim fibers would be less helpful.
The discovery of cross transfers and multiple fiber transfers between the suspect's
clothing and the victim's clothing dramatically increases the likelihood that these
two individuals had physical contact.
Natural Fibers
Many different natural fibers that come from plants and animals are used in the
production of fabric.
Cotton fibers are the plant fibers most commonly used
in textile materials
The animal fiber most frequently used in the
production of textile materials is wool, and the most
common wool fibers originate from sheep.
Synthetic Fibers
More than half of all fibers used in the production of textile
materials are synthetic or man-made.
Nylon, rayon, and polyester are all examples of synthetic
Cross-section of a
man-made fiber
Fibers under a microscope
It’s time to examine
some hairs and fibers!
Hair & Fiber Identification Lab
Your team will need to use a microscope
to document all the hairs and fibers in
your set.
Write the name of the hair or fiber on the
line and then draw what you see under
medium or high power. Be sure to
indicate the power of magnification!
Add a description that highlights the
unique characteristics of each hair and
fiber sample.
Pay attention to details to help you
identify samples during the Hair & Fiber
Challenge activity.
Can you identify the animal hairs shown?
Think About It …
(1) In which samples are we viewing the cuticle? How do they compare?
(2) In which samples are we viewing the medulla? How do they compare?
(3) What characteristics can be used to identify hair samples?
Can you identify the types of fibers shown?
Think About It …
(1) Which samples are natural fibers?
(2) Which samples are synthetic fibers?
(3) What characteristics can be used to identify fiber samples?
Types of Animal Hairs - Key
Types of Fibers - Key
Acrylic Yarn
Cotton Yarn
Nylon Rope
Polyester Yarn
Rayon Rope
Wool Yarn