Echinopsis candicans has a shrubby growth habit, with individual stems up to 60 cm (24 in) tall. The plant as a whole can be as much as 3 m (10 ft) across. The stems are light green, with a diameter of up to 14 cm (5.5 in) and have 9–11 low ribs. The large white areoles are spaced at 2–3 cm (0.8–1.2 in) and produce brownish yellow spines, the central spines being up to 10 cm (3.9 in) long, the radial spines only up to 4 cm (1.6 in).
The fragrant white flowers open at night. They are large, up to 19 cm (7.5 in) across and 18–23 cm (7.1–9.1 in) long.
The species was first described in print by Joseph zu Salm-Reifferscheidt-Dyck in 1834 in his work Hortus Dyckensis, where he attributed the name Cereus candicans to Gillies. In 1920, Britton and Rose placed the species in Trichocereus. In a 1987 publication, David Hunt transferred the species to the genus Echinopsis, attributing this placement to Frédéric Weber. The broad circumscription of Echinopsis remains controversial; the genus is accepted not to be monophyletic.
- Anderson, Edward F. (2001), The Cactus Family, Pentland, Oregon: Timber Press, ISBN 978-0-88192-498-5, pp. 260–261
- Salm-Reifferscheidt-Dyck, Joseph zu (1834), Hortus Dyckensis, Düsseldorf, OCLC 311220759, p. 335.
- IPNI Plant Name Query Results for Echinopsis candicans, The International Plant Names Index, retrieved 2012-04-27
- Nyffeler, R. & Eggli, U. (2010), "A farewell to dated ideas and concepts: molecular phylogenetics and a revised suprageneric classification of the family Cactaceae", Schumannia, 6: 109–149, doi:10.5167/uzh-43285