It was first recorded by Charles Darwin on Santiago (James) Island.

All were treated by David Hunt in 2006 as included within O. galapageia, a placement accepted by the IUCN Red List as of 2017, although they had been assessed as separate species in 2000.

[1] Plants of the World Online also accepts the placement within O. galapageia, and includes Opuntia echios, in most cases placing the species in an infraspecific taxon (see the list below).

A large number of varieties and other infraspecific taxa have been named.

As of June 2021[update], Plants of the World Online accepts the following:[6] Two other infraspecific taxa that have been named are not recognized by Plants of the World Online as distinct from the species:[6] Opuntia galapageia is endemic to the Galápagos Islands.