The Latin name of this species refers to the sour taste of its fruits, used for food in the native areas. It is an extremely thorny and imposing cactus, consisting of a central columnar stem, at the apex of which, with growth, an abundant branching develops similar to the crown of a tree which, in nature, can reach up to 6 meters high! The body of the cactus, of a beautiful emerald green, is equipped with deep longitudinal ribs along which, from large woolly areoles, thin and glassy radial thorns emerge; the central thorns, on the other hand, are much longer, up to 20 cm in large specimens, and tend to turn from reddish-brown in young plants to greyish in mature ones. The wild aspect of E. acid softens when, near the apex, large white flowers with reddish veins along the petals bloom.