1. Plant Development
Chapter 40_AP

2. Establishing a Seed Establishment of embryo Food supply is established
Development continues and meristem regions are established
Three basic tissue types are established
Dermal, vascular, and ground
Food supply is established
Ovule tissue becomes transformed to hard protective covering
Enters dormant phase

3. Early Cell Division First division is asymetrical
Smaller daughter cell will become embryo
Larger cell divides forming elongated suspensor
Links embryo to nutrient tissue of seed
Cells of embryo nearest suspensor become root

4. Establishing Tissues
Three basic cell types established during globular stage
Root-shoot axis
Formation of root & shoot is independent
Protoderm = dermal tissue
Ground meristem = ground tissue
Procambium = vascular tissue

5. Heart-shaped embryo & ball with single bulge
Bulges are cotyledons
Produced from embryonic cells
Called morphogensis
Food storage
Sporophyte nutrients transferred to embryo via suspensor
Endosperm is forming (double fertilization)
In dicots, endosperm is used up & nutrients stored in cotyledons

6. Seed Formation Seed = embryo & stored food
Early in development embryo stops developing
Outer layers of ovule become seed coat
Very stable in dormant state
Germination cannot happen without water & oxygen

7. Seeds important adaptively
Maintain dormancy under unfavorable conditions
Maximum protection for vulnerable young plant
Contain stored food to feed young plant until photosynthesis
Adapted for dispersal

8. Specific adaptations ensure germination at right time
Cones open when exposed to heat from fire
Germinate in cleared habitat full of nutrients
Inhibitory chemicals must be leached from seed coat
Guaranteeing sufficient water
Some must be ingested first
weaken seed coat

9. Fruit Formation
Three layers of ovary wall account for diversity of fruit types
Three genotypes make complete fruit
Fruit and seed coat from sporophyte
endosperm
Embryo
Dispersal of fruit
Fleshy covering = dispersed by birds/other animals
Hooked spines = carried by animals
Nuts = buried by squirrels
Wings = air
Floating seeds = water

11. Germination Begins when seed absorbs water
Metabolism resumes
Oxygen needs to be present for cellular respiration
Imbibition is not enough
Signals from environment still needed
Light
Series of cold days
Series of days at right temperature

12. Requires utilization of amyloplasts
Colorless starch storing plastids
In grains, single cotyledon modified into scuttelum
Food that is used up before endosperm
Later, transfers nutrients from endosperm to embryo
Root emerges and anchors young plant in soil, then shoot emerges