plant reproduction

seed development

• ovule → seed

Inside the seed:

• Fertilized egg becomes embryo (baby plant)

• Food tissue (endosperm) forms to feed it

fruit development

• ovary → fruit

Purpose:

• Protect the seed

• Spread it to new places

what is a seed coat

hard outer shell of seed

purpose of seed coat

• protects embryo

• keeps water in

• prevents damage

• delay germination until suitable conditions

seed dispersal

seeds get carried away by

• wind (dandelions)

• water (coconut)

• animals (eaten fruits, burrs)

• bursting pods

seed germination

this is when a seed starts to grow

germination needs:

1. water

2. oxygen

3. warmth

Water activated enzymes → stored food feeds the embryo → root grows first

radicle

baby root

• comes out first

• anchors plant

• absorbs water

hypocotyl

baby stem below the seed leaves

• pushes seedling up

• may lift seed leaves above soil

2 main stages in the life cycle of flowering plants

• sporophyte : big leafy plant

• gametophyte : tiny stage inside pollen/ovule

Flowers make what?

pollen (male)

ovules (female)

fertilization → seed → new plant

process of sporic life cycle/alternation of generations

sporophyte → meiosis → spores → gametophyte → gametes → fertilization → sporophyte

alternation of generations

• plants switch between diploid form (sporophyte) and haploid form (gametophyte)

  • “main stage” includes both but usually plants in the sporophyte is dominant (bigger, longer-lived, visible plant)

• seen in plants

zygotic life cycle

• haploid dominant

• only zygote is 2n

gametes fertilize → zygote (2n) → zygote undergoes meiosis immediately → produces haploid cells → grow into new haploid individuals

asexual reproduction

new plant without seeds

• only 1 parent

• offspring are clones

• faster reproduction

types of asexual reproduction

• division

• grafting

• leaf cutting

• stem cutting

division

split a plant clump into pieces

grafting

attach a branch of one plant onto another’s roots, they grow together

leaf cutting

leaf grows roots + shoots

stem cutting

plant a stem piece (grows roots)

artificial propagation

humans making plants reproduce without seeds

types of artificial propagation

• root cutting

• simple layering

• air layering

• tissue culture

root cutting

plant new part of root → new plant

simple layering

bend branch to ground → bury part → roots form → cut layers

air layering

root grow on branch still attached

tissue culture

makes tiny identical parts