07 - Seed to tree

Two mobile life cycle phases

seed dispersal syndromes

polination syndrome

why do you need seed dispersal

Without seed dispersal adaptations, most seeds are deposited close to mother plant

why is it bad to most seeds are deposited close to mother plant

→ parent-offspring competition for space & resources

→ mating btw. closely related individuals: inbreeding depression

Explosive self dispersal DIY:

Ballistochory

Wind dispersal:

Anemochory

Water dispersal:

Hydrochory

“Internal hitchhiking”:

Endozoochory

“External hitchhiking”:

Exozoochory

Ant dispersal:

Myrmecochory

Gravity+:

Barochory & 2ndary dispersal by animals

Ballistochory

seeds catapolted away

build up pressure slightest force causes to catapolt

Anemochory:

hairs → allows seed to be picked up by wind

parachute → good adaptation to move away (dandilions)

wings (Winged maples)

Hydrochory

• water travel

• need a seed coat so seed can curvive in salt water

• contains airpocket which keeps them floating

eg coconut - good floater, well defense shell, survive long period

Exozoochory

hooks grab onto fur or hair and fall out when you move

Endozoochory

animals eat it and poop it up

eg. berries indicate with colour when seed inside is ripe

their seed coat = strong so it survives the acidiic environemtn of the stomach and teeth

Myrmecochory

tranfered by ants

Myrmecochory relationship

→ Symbiotic relationship: plant → seed dispersal; ant → food

Elaiosomes

(elaios- oil, some- body): food for ants

Fleshy structure attached to seeds

Rich in lipids and proteins

Barochory and small animal dispersal

fall down and animal carry

Big, heavy seeds Starch-rich, oil-rich → great food Survive winter: seed caching! Some caches: forgotten → tree seedling recruitment

Scatter hoarding

puts seeds all over the place

Larder hoarding:

in one place

Comparison of dispersal distances

testa

Contains plant embryo1 , covered with protective seed coat

radicle

Embryo: embryonic shoot, root3

embryonic leaves

cotyledons4

endosperm

Food for embryo

food storage cells inside seed; not part of embryo

how is endosperm developed

developed through Double Fertilization

Double Fertilization

(angiosperms only): parallel to fertilization of egg by pollen (→ embryo), one pollen nucleus (1n) fertilizes ‘central cell’ (2n) inside ovule → endosperm (3n)

do all angios keep double fertilization goingn

no

Early on: abortion of endosperm

Food for embryo stored in cotyledons → cotyledons do not photosynthesize

Cotyledons C replaced by first true leaves T

process of df when kept going

Endosperm: food for embryo

Food lasts until cotyledons start photosynthesis

Cotyledons C replaced by first true leaves (T)

In which of the 7 dispersal mechanisms do elaiosomes play a role?

Myrmecochory

In which seed dispersal mode does the plant need to invest into a seed coat which is resistant to grinding or abrasion or acid

Endozoochory

In which seed dispersal mode do plants need to construct parts which are under elastic pressure, where the power gets released as the seed matures and dries out

Ballistochory

Which seed dispersal mode was the role model for the invention of Velcro?

Exozoochory

Which dispersal mechanism involves seeds which are especially light and non-dense

Anemochory

1. Which seed dispersal mode relies on hoarding

Barochory

Which seed dispersal mode is more common on high mountains above tree line, on islands and generally in areas without much tree cover?

Anemochory

For which seed dispersal mode are fur and feathers important?

Exozoochory

Which seed dispersal mode is especially important for Ontario’s spring ephemerals in forests?

Myrmecochory

In which seed dispersal mode does the plant indicate to the dispersal agent when seeds are ripe?

Endozoochory

1. Which seed dispersal mode relies on the forgetfulness of the disperser?

Barochory

When an endozoochorous fruit is eaten by an animal vector, the seed is most likely still viable after the gut passage

tru

When an seed dispersed through barochory is eaten, it is still viable after gut passage.

false

What is the food source for the embryo?

Endosperm

1. What is the name for the first generation leaves or embryonic leaves?

Cotyledons

1. What organ develops through double fertilization?

Endosperm

1. All angiosperms at least initiate the development of the endosperm

true

ploidy levels cotyledons

diploid

ploidy levels - embryo

diploid

ploidy levels - endosperms

triplpoid

Many angiosperms abort the development of the endosperm and the energy needed for the embryo gets absorbed into the cotyledons

True

In angiosperms which store the food for the embryo in the cotyledons, the cotyledons are typically photosynthetic

false

1. When you are eating popcorn, what are you eating? Choose all appropriate solutions

food for the embryo, embryo, endosperm

1. When eating a peanut, you are mostly eating the…

Cotyledons

1. Where in the tree of life was the endosperm invented?

angio