Plant HormonesAbscisic Acid

Inhibits shoot growth

closes stomates

induces dormancy

promotes leaf abscission

Plant HormonesAuxin

Stimulates cell division, elongation

Stimulates root formation

Stimulates growth of flower parts

Promotes apical dominance (inhibits lateral growth)

Plant Hormones

Cytokinins

Stimulate cell division

Stimulate leaf expansion

Promote lateral growth

Plant HormonesEthylene

Stimulates release of dormancy

Stimulates flower opening

Promotes fruit ripening

Plant HormonesGibberellins

Stimulates cell division and elongation

Can cause seedless fruit development

Increases size of fruit

Phototropism

Bending of a plant toward the light

Occurs because auxin moves to shaded side

Cells on shaded side elongate

Phototropism

Geotropism/Gravitropism

Plant response to gravity

Roots show positive response

Shoots show negative response

Thigmotropism

Plant response to touch