1. TROPISMS &
Adaptations

2. Tropisms
A Tropism is a plant’s directed growth towards or away from a stimulus.

3. Tropisms We will cover 4 tropisms. Gravitropism Phototropism
Thigmotropism
Hydrotropism

4. Plants use gravity for orientation
Gravitropism
Gravitropism is a plant’s movement and growth in response to gravitational pull. The roots grow into the soil while the shoots grow in the opposite direction towards the light.
Plants use gravity for orientation

5. Plants need light to grow.
Phototropism
Phototropism is a plant's growth response to light. More sunlight energy means more photosynthesis.
Plants need light to grow.

6. Thigmotropism is a plant's response and movement to physical contact.
For instance, climbing plants with coil-like structures (tendrils), first bend and turn until they touch a suitable supporting object, then they coil around it.

7. Hydrotropism
Hydrotropism is a plants growth response to water. Roots, grow towards moist soils to avoid draught stress. Once a root cap has sensed water it bends and then the root grows towards it.

8. How plants adapt in different biomes
Plant Adaptations
How plants adapt in different biomes

9. Desert – Abiotic Factors
Very DRY
A lot of direct sunlight on plants
Soil is sandy or rocky; doesn’t hold much water
Plants lose a lot of water

10. Desert – Plant Adaptations
SMALL SPINES instead of leaves – slows water loss
Deep tap roots or extensive surface roots.
Some have WAXY COATINGS on stems and leaves
Some have fuzzy or hairy leaves to trap condensation
Many plants use wind to spread seeds (tumbleweeds)

11. Grassland – Abiotic Factors
HOT summers and COLD winters
Rainfall is uncertain; drought is common
Soil is very rich in organic matter
Windy

12. Grassland – Plant Adaptations
Prairie grasses have NARROW leaves – lose less water
SOFT STEMS allow grasses to bend in wind
Extensive fibrous roots to find water
Grass grows from BASE, not tip; can GROW BACK easily if burned or eaten
Are WIND POLLINATED

13. Tropical Rain Forest – Abiotic Factors
Warm and RAINY!
DARK because of thick plant growth in the canopy.

14. Tropical Rain Forest – Plant Adaptations
Broad leaved for more photosynthesis.
DRIP TIPS & WAXY SURFACES allow water to run off
Some plants GROW on others to reach sunlight - epiphytes (Orchid on tree)

15. Deciduous Forest – Abiotic Factors
4 distinct seasons
Plenty of rain
DARK under taller trees

16. Deciduous Forest – Plant Adaptations
BROAD LEAVES to catch sunlight
THICK BARK to protect against the cold
Deciduous trees DROP LEAVES in winter to avoid losing water
Some seeds have WING SHAPES to be caught and spread by the WIND
Maple seed

17. Taiga – Abiotic Factors
COLD, DRY winters/WARM summers
Some areas have PERMAFROST (permanently frozen ground)

18. Taiga – Plant Adaptations
Many trees are evergreens – can photosynthesize anytime temperature is high enough
Needle-like leaves to reduce water loss and shed snow in winter
Dark needles allow more solar heat to be absorbed

19. Tundra – Abiotic Factors
COLD year-round!
All ground is PERMAFROST! (permanently frozen)
DRY – only gets a little bit of snow or ice

20. Tundra – Plant Adaptations
Small and low-growing (mosses, grasses & sedges)
Dark in color to help absorb solar heat
Grow in clumps to help protect each other from wind and cold

21. Plant Adaptations Involving Animals
Seed Dispersal
Sticky Burrs
Fruit

22. Plant Adaptations Involving Animals
Chemical Defense
Poisonous / Deadly When Eaten
Skin Irritant
Poison Ivy
Foxglove
Bull Nettle
Milkweed

23. Plant Adaptations Involving Animals
Physical Defense
Spines and/or Thorns
Cacti
Roses