BIOA02H3 Lecture Notes - Lecture 6: Myrmecochory, Seed Dispersal, Hitchhiking
27 Apr 2018
School
Department
Course
Professor
BIO A02 – Module 1 Notes Hassan Alibhai
Plant Form and Function Page 24
From Seed to Tree
•Seed to Germination
◦Dispersal
◦Anatomy
◦Germination
•Seed dispersal periods are based on the period between fertilization (fusion) and the developing
diploid sporophyte => “potentially” long distance
The Reason For Seed Dispersal
•Not doing so has fatal effects
◦Parent-offspring competition for space as well as nutrients
◦Mating between related individuals possible (inbreeding)
Types of Seed Dispersal
•The suffix “chory” represents dispersal for some sort, and each prefix represents the method
Ballistochory Anemochory Hydrochory Exozoochory Endozoochory Myrmecochory Barochory
Explosive
self dispersal
Wind Water Attaching a
seed to an
animal
Eaten by an
animal
Ants
(important)
Gravity,
large seeds
External
hitchhiking Internal
Ballistochory
•“Do-it-yourself” => unzip, curl, flip, twist
•Explosions within the plant, (ex. Jewelweel) has the
potential to catapult seeds 1 meter away
◦Tensions are released within the seed
Ameochory
•Two methods of travel - “hairs” or “wings” and “parachutes”
“Hairs” “Parachutes”
Winged maples,
mikweed pods
Wish maker flower
spreads out
1- 5 meter
Dispersal!
BIO A02 – Module 1 Notes Hassan Alibhai
Plant Form and Function Page 25
Hydrochory
•Generally hard and sturdy seeds that are able to be
transported great distances (up to 1000s of kms) through
rivers and ocean currents
◦Seabeans and coconuts are common examples
Exozoochory
•Hooks and barbs are used to ensue that the seed “sticks” to
animals that pass by the plant
◦“velcro” analogy
•The same seeds that get stuck to you when you walk through
a forest
◦Travel distance: less than 15 meters
Endozoochory
•Objective: animals eat seeds => will poop out => feces of the animal will fertillize the seed
◦Because animals walk quite a bit before they produce feces, travel distance can be several
kilometers and depends on the animal in question
◦Also needs to be strong enough to go through the plant digestive system
▪If it happens to be a bird, that can be several hundred kilometers (several km for land)
•Critical to know when the seed is ripe
◦Unripe seeds are generally bland (green
or grey) in colour and hard
◦Ripe seeds are colourful to attract
animals and such
Myrmecochory
•Elaiosomes => seeds grow to “reward” bodies that are fleshy in structure
◦Rich in lipids, proteins, and nutrients
•Elaiosome + seed = diaspore
◦Diaspore is fed to ant larvae, and consumed
◦Elaisome is consumed, seed is discarded
•Symbiotic relationship => plant → seed dispersal; ant →
food
•Common in ontario “spring flowers”
•Ants are smol dudes
◦Travel distance is typically only 1-5 meters
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