MEANS OF SEED DISPERSAL
A LECTURE
BY
MR. ALLAH DAD KHAN

BY SPLITTING SUDDENLY - EXPLOSIVE
ACTION OF FRUITS

HYDROCHORY:
Many aquatic (water) and some terrestrial (ground) plant species use
hydrochory, or seed dispersal through water. Seeds can travel for
extremely long distances, depending on the specific mode of water
dispersal. The water lily is an example of such a plant. Water lilies'
flowers make a fruit that floats in the water for a while and then drops
down to the bottom to take root on the floor of the pond. The seeds of
palm trees can also be dispersed by water. If they grow near oceans, the
seeds can be transported by ocean currents over long distances,
allowing the seeds to be dispersed as far as other continents. Mangrove
trees live right in the water. Their seeds fall from the tree and grow roots
as soon as they touch any kind of soil. During low tide, they might fall in
soil instead of water and start growing right where they fell. If the water
level is high, however, they can be carried far away from where they fell.
Mangrove trees often make little islands as dirt and other things collect
in their roots, making little bodies of land.

BY WATER
The fruits of most water plants have buoyant, waterproof coverings that
allow them to float and disperse their seeds by water.

ALLOCHORY
Anemochory (wind dispersal) is one of the more primitive means of
dispersal. Wind dispersal can take on one of two primary forms: seeds
can float on the breeze or alternatively, they can flutter to the ground.
The classic examples of these dispersal mechanisms include
dandelions, which have a feathery pappus attached to their seeds and
can be dispersed long distances, and maples, which have winged seeds
(samara) and flutter to the ground

BY WIND
Some seeds are enclosed in wing-like husks (with one or two propeller
blades) or fluffy coverings that help them drift some distance away from
the parent plant.

DANDELION SEEDS FLOAT AWAY IN THE WIND. TO MAKE SURE AT
LEAST SOME OF THE SEEDS LAND IN A SUITABLE GROWING PLACE,
THE PLANT HAS TO PRODUCE LOTS OF SEEDS.

ZOOCHORY: DISPERSAL BY ANIMALS

EPIZOOCHORY:
Seeds can be transported on the outside of vertebrate animals (mostly
mammals), a process known as epizoochory. Plant species transported
externally by animals can have a variety of adaptations for dispersal,
including adhesive mucus, and a variety of hooks, spines and barbs. A
typical example of an epizoochorous plant is Trifolium angustifolium, a
species of Old World clover which adheres to animal fur by means of
stiff hairs covering the seed. Epizoochorous plants tend to be
herbaceous plants, with many representative species in the families
Apiaceae and Asteraceae. However, epizoochory is a relatively rare
dispersal syndrome for plants as a whole; the percentage of plant
species with seeds adapted for transport on the outside of animals is
estimated to be below 5%. Nevertheless, epizoochorous transport can
be highly effective if seeds attach to wide-ranging animals. This form of
seed dispersal has been implicated in rapid plant migration and the
spread of invasive species

ENDOZOOCHORY:
Seed dispersal via ingestion by vertebrate animals (mostly birds and
mammals), or endozoochory, is the dispersal mechanism for most tree
species. Endozoochory is generally a coevolved mutualistic
relationship in which a plant surrounds seeds with an edible, nutritious
fruit as a good food for animals that consume it. Birds and mammals
are the most important seed dispersers, but a wide variety of other
animals, including turtles and fish, can transport viable seeds. The
exact percentage of tree species dispersed by endozoochory varies
between habitats, but can range to over 90% in some tropical
rainforests

MYRMECOCHORY:
Seed dispersal by ants is a dispersal mechanism of many shrubs of the
southern hemisphere or understorey herbs of the northern hemisphere.
Seeds of myrmecochorous plants have a lipid-rich attachment called
the elaiosome, which attracts ants. Ants carry such seeds into their
colonies, feed the elaiosome to their larvae and discard the otherwise
intact seed in an underground chamber. Myrmecochory is thus a
coevolved mutualistic relationship between plants and seed-disperser
ants. Myrmecochory has independently evolved at least 100 times in
flowering plants and is estimated to be present in at least 11 000
species, but likely up to 23 000 or 9% of all species of flowering plants.

SEED PREDATORS,
which include many rodents (such as squirrels) and some birds (such as
jays) may also disperse seeds by hoarding the seeds in hidden caches.
The seeds in caches are usually well-protected from other seed
predators and if left uneaten will grow into new plants. In addition,
rodents may also disperse seeds via seed spitting due to the presence
of secondary metabolites in ripe fruits.

SECONDARY ZOOCHORY:
Secondary dispersal by animals: Seeds may be secondarily dispersed
from seeds deposited by primary animal dispersers. For example, dung
beetles are known to disperse seeds from clumps of feces in the
process of collecting dung to feed their larvae.

ANTHROPOCHORY: DISPERSAL BY HUMANS
Dispersal by humans (anthropochory) used to be seen as a form of
dispersal by animals. Recent research points out that human dispersers
differ from animal dispersers by a much higher mobility based on the
technical means of human transport. Dispersal by humans on the one hand
may act on large geographical scales and lead to invasive species

BY ANIMALS / HUMANS
Animals often serve as seed carriers. Seeds (with sticky hairs, bristles,
hooks, or barbs) are transported by sticking to the fur of animals or on
the clothing of human beings.
Birds and other animals eat the fleshy fruits and discard the seeds or they
may eat both but the seeds are not digested and are passed out with
their droppings, often far away from the parent plant.

THE KERERŪ IS IMPORTANT IN THE SEED DISPERSAL OF LARGE NATIVE
BERRIES IN FOREST ECOSYSTEMS. TREES SUCH AS THE KAWAKAWA RELY
ON NATIVE BIRDS FOR SEED DISPERSAL

BANKSIAS, EUCALYPTS AND OTHER AUSTRALIAN PLANTS RELY ON FIRE
TO HELP SPREAD THEIR SEEDS.