IU is indeed a United Left and not a Green Left, but in most places they have run in coalition with Left Green parties, and in Catalonia and Valencia they ran in coalition with "Iniciativa" (a Green Left party).
Currently, in the Congress of Deputies IU and IC-V caucus together.
So, things have progressed a bit in the years I've been away. The economy needs to be thought of as a garden, not as a wild ecosystem