2. Echinopsis Zuccarini (1837: 675)

Type (designated by Zuccarini 1843: 4):— Echinopsis eyriesii (Turpin) Zucc. ≡ Echinocactus eyriesii Turpin (1830: 157 plate 2).

Species richness:— 50 species, of these three occur in Brazil and two in Rio Grande do Sul (Carneiro et al. 2016), E. oxygona and E. eyriesii (Oliveira Deble 2011) .

General distribution:— Echinopsis is distributed in southern Brazil, Uruguay, Bolivia, Paraguay, and Argentina (Hunt et al. 2006).

Distribution in Santa Maria river basin:— Echinopsis oxygona (Fig. 2B), presenting a wide distribution of the study area (Fig. 3) and in Rio Grande do Sul, which may occur mainly in rocky outcrops, native fields associated with saxic vegetation,

Morphologic notes:— This species has 8–10 ribs, with flowers. The infusiveness of rose or white-rose petals up to 20 cm long blooms from October to February, bearing fruit shortly thereafter.