Reproduction of Seed Plants

Alternation of Generation

• All plants life cycle alternates

Diploid Sporophyte Haploid Gametophyte

• Sporophyte = Entire Plant

• Gametophyte = hidden in plant– Gymnosperm gametophyte = inside cones– Angiosperm gametophyte = inside flower

Gymnosperm vs Angiosperm• Produce Cones where

reproduction occurs• Pollen Cones (males)• Seed Cones (females)• Ovules = meiosis

makes haploid female gametophytes

• Produce Flowers where reproduction occur

• Sepals = protect flower while developing

• Petals = colored; attract insects

• Stamen– Filament & Anther (male)

• Carpel– Ovary, Style, Stigma

(female)

Male Structure Female Structure

Life Cycle of Gymnosperm• Takes 2 years to complete

• Wind carries pollen (male)

• Lands on seed cones & pollinates

• Pollen Tube forms & allows pollen to reach female gametophyte

• New Sporophyte Plant Formed!

Life Cycle of Angiosperm

• Anther = produces male gametophytes

• Ovary = produces female gametophytes

• Stigma = sticky portion; pollen attaches to it

• Seeds develop inside

protective structures

• Pollinated by wind or animal– Animal pollination WORKS BEST!!!!– Animals transfer pollen from one flower to

another

Double Fertilization

• Two fertilizations occur between male & female gametophytes:– One forms into

EMBRYO– Second forms into

ENDOSPERM• Endosperm nourishes

the seedling as it grows

Fruit Development

• Angiosperm seeds mature– Ovary walls thicken to form a fruit that hold

seeds

• Fruit = any seed surrounded by embryo wall– Includes: Apples, Grapes, Strawberried– Includes Vegetables: peas, corn, beans, rice

Seed Dispersal• Animals: eat fruits and poop out seeds

• Wind: light-weight seeds can be carried

• Water: seeds can float allowing water transport

Dormancy & Germination• Dormancy = embryo is alive, but doesn’t

grow– Caused by environment not being good enough– Temperature and moisture needs to be ideal

• Germination = early growth of plant embryo– Monocots = single cotyledon beneath

ground– Dicots = two cotyledons grow above ground

Plant Responses• Plants respond to different factors:– Phototropism = response to light• Plants grow toward light

– Gravitropism = response to gravity• Plants grow against gravity

– Thigmotropism = response to touch• Plants react to touch• Vines

Hormones• To respond to stimuli, plants use

hormones

• AUXINS–Most important–Makes shaded area of plant grow more–Makes area affected by gravity grow more

• Cytokinins– Stimulate cell division & dormancy of seeds

• Gibberellins– Increases size of stems & fruits

Evolve to Environment

• Water plants can hold more gases

• Desert plants can hold more water

• Marine plants can tolerate salt

• Carnivorous Plants:– Some can digest organisms– Some are parasitic on other plants