Opuntia megasperma
Commonly known as tuna, it is the most emblematic, dominant, and ecologically important terrestrial plant of the arid zone ecosystem.
It possesses a true woody trunk — thick and covered with scaly brown bark — which is spineless in the adult stage. It reaches impressive heights of 3 to 5 meters.
The tree-like growth form is an evolutionary adaptation to keep its nutritious pads, flowers, and fruits out of reach of voracious terrestrial herbivores — including giant tortoises.
Despite its historical abundance, the opuntia of San Cristóbal has suffered severe impacts due to human settlement and the introduction of invasive animals.
