Here's a breakdown of the classification of cactus:

* Domain: Eukarya (organisms with cells containing a nucleus)

* Kingdom: Plantae (plants)

* Phylum: Magnoliophyta (flowering plants)

* Class: Magnoliopsida (dicotyledons)

* Order: Caryophyllales

* Family: Cactaceae (cactus family)

So, while cactus is a very specific type of plant, it is still part of the larger group of all plants!