Book 16, Question 67
Why Do So Many Desert Plants Have Thorns or Spines?
Desert plants have thorns and spines because they hold precious water, and animals would eat them! Sharp points make a bite painful, so most animals give up. Spines can also do other helpful jobs.
More fun facts
- Cactus spines are leaves that changed shape over a very long time.
- Scientists think defense against plant eaters was likely the first job of cactus spines.
- A cluster of spines protects a cactus better than spines spread far apart.
- Spines also shade the stem and help protect it from extreme temperatures.
- In some cacti, spines grow longer in hotter, drier places.
- Some cactus spines collect fog, and the water can move along the spine toward the stem.
- Spines can even stop birds from perching on a cactus stem.
Sources: jpacd.org
Questions kids ask
Do all desert plants have spines?
No. Many use other tricks, like bad taste, strong smells, or hairy leaves, to stay safe and cool.