Expert: Greg Simpson - 8/26/2005

Question
How does a cactus protect itself?

Answer
Dear Emily,

A cactus protects itself from:

The sun by growing spines and having ribs. Both have the function of creating shade on the plant itself.

From animals by growing spines and incorporating alkaloids in their flesh. The spines are on obvious deterrent while the alkaloids make them taste bad.

From wind simply by their shape. They have very little wind resistance.

From water loss by only opening their stomata at night. Since the plant only "breathes" at knight when temperatures are down, less water is lost. That is also why cactus flowers only bloom at night and generally only last a day.

I hope this is what you were looking for.

Sincerely,

Greg