Undoubtedly, one of the great cactus genera, both for its size—which in some species can reach colossal proportions—and for its wide geographic distribution, spanning much of South America, as well as its remarkable visual appeal. However, it also includes more discreet plants, with unassuming appearances and dimensions, which can still provide great ornamental value and brighten our gardens.

Over time, this genus has absorbed other genera, such as *Lobivia*, *Trichocereus*, *Helianthocereus*, and *Soehrensia*. These had been distinguished primarily by their appearance, which was very different from that of the large columnar *Echinopsis*. However, subsequent research demonstrated that their physiology and fundamental taxonomic characteristics coincided to such an extent that maintaining separate genera was not justified.

Additionally, there are other genera with a tendency to be integrated into *Echinopsis*, such as *Chamaecereus*, *Hymenorebutia*, *Neolobivia*, *Pseudolobivia*, and *Setiechinopsis*. In any case, taxonomic currents persist that could lead to the separation of some of them in the future, especially in light of new genetic analyses.

It is difficult to provide a description that encompasses the entire genus, as it is extremely variable:

**Morphology:** Extremely diverse, ranging from large columnar species that can reach 7–8 meters in height and diameters of up to 80 cm, to small globular plants. Specimens can be solitary, branched or unbranched, and even strongly clumping.

**Ribs:** Generally well-defined, although exceptions exist. Their number is highly variable, ranging from 6–7 to as many as about 40.

**Spination:** Very diverse, with long and thick spines, straight or curved, short and robust, and even hooked.

**Flowering:** Generally large-sized across the genus, though it is especially striking in the smaller species. The flowers are almost always funnel-shaped, with an elongated floral tube. They appear on the side of the stem, tending to cluster near the apex. The color range spans from white and yellow to red.

**Fruits:** Generally fleshy and dehiscent, though not always. They contain numerous small, black seeds. Many of them are edible.