Diversity

There are about 1800 different species of cacti in the world.
All cacti have some adaptations to support efficient water use of course.
No known fossils of cacti exist to explain their evolutionary history- age estimates for species are based on geographical locations, continental divides and mountain formations.
I think that the incredible diversity of cacti is intriguing.
You all will definitely be seeing more of this diversity- I apologize in advance. :)