PLANT RESPONSES
tropisms
GEOTROPISM
Geo= “earth”
Tropism= Greek for “a turning”
Roots grow down, leaves/stems grow up
PHOTOTROPISM
Photo= “light”
Tropism= “a turning”
Plants grow toward light
HYDROTROPISM
Hydro= “water”
Tropism= “a turning”
Plants grow toward moisture
THIGMOTROPISM
Thigmo= “touch”
Tropism= “a turning”
Plants respond to touch
 Tendrils curling around a pole
 Fly trap snapping on a fly
 Leaves curling in when bumped
http://www.youtube.com/watch?v=p77AZTMuMCg
http://www.youtube.com/watch?v=BLTcVNyOhUc
ADAPTATIONS
Traits that allow an
organism to survive
SEEDS= PERIOD OF COLD
Apple, peach, pine, ash trees need cold before seeds sprout
SEEDS= PERIOD OF HEAT
Need a forest fire to burn off the hard outer covering
Charred soil= high nutrients for new growth
Ex. Lodgepole pines, Jack pines
Sometimes seeds need to be digested before they grow
SEEDS= PERIOD OF SHORT BLOOMING
Some desert plants have a short life cycle
Sprout, bloom, make seeds after a heavy rain
Plants die, but seeds are ready to sprout the
next time it rains
Can be as short as 10 days
LEAVES= CONSERVING WATER
Lose leaves in cold weather (deciduous)
Needlelike leaves (aka-spines)
 small surface area
 Don’t lose as much water
Waxy/woolly coatings seal in moisture
Tiny leaves reduce evaporation
OTHER PLANT ADAPTIONS
Water Storage
Food Storage
Large cactus can absorb 1,000L
Longleaf pine seedlings hardly
grow the first six years
(260 gal.)
Large saguaro cactus= 9,000L
 2,340 gal.
 Enough to last 3 yrs. without rain
 Store food in roots
 Grow fast the 7th year
 Thick, fire-resistant bark
DESERT ROOTS
Deep
Wide
RAINFOREST ROOTS
Don’t have roots!
Little ones to anchor onto other plants
Catch rainwater, funnels to roots
Geotropism
Phototropism
Hydrotropism
Thigmotropism
QUIZ TIME!!!
Which tropism goes
with which picture???
Geotropism
Phototropism
Hydrotropism
Thigmotropism