Strophocactus

Genus scope and historical names

Plants of the World Online accepts four species in Strophocactus, S. brasiliensis, S. krammii, S. sicariguensis and S. wittii. Pseudoacanthocereus is a generic synonym. The former Strophocactus testudo and S. chontalensis belong to the separate genus Deamia. [2-WWW] [Korotkova et al. 2017, POWO 296608-2, 12 October 2026, pp. 13–15, 33–34]

In 2017, Korotkova, Borsch and Arias analysed four plastid DNA regions in a broad sample of cacti. S. wittii grouped with the two species then treated as Pseudoacanthocereus, outside the core Hylocereeae lineage. The authors united these three species under the older name Strophocactus. S. krammii was not included in that analysis. [Korotkova et al. 2017, pp. 1, 4–5, 7–8, 13–15, 33, 46]

Stems, roots and contrasting habitats

S. wittii bears broad, very thin stems appressed to bark. Numerous aerial roots attach it to the trunk, and sites near Manaus are associated with seasonally flooded igapó forests. S. brasiliensis and S. sicariguensis have a shrubby habit, slender stems and tuberous roots. The former comes from the Brazilian caatinga and agreste transition zone, the latter from northern Colombia and northwestern Venezuela. [Barthlott et al. 1997, pp. 178, 182–183, Korotkova et al., pp. 13–14, POWO, 12 October 2026] [Korotkova et al. 2017, pp. 178, 182–183, Korotkova et al., pp. 13–14, POWO, 12 October 2026] [2-WWW]

Flowers and dispersal

The species discussed in the revision share elongated floral structures and bristles arising from areoles. The dispersal mechanism of S. wittii was established in a separate study of that species. Air chambers in its seed coat keep the seeds afloat. This specialization is described in the S. wittii account. [Korotkova et al. 2017, pp. 13–14, Barthlott et al., pp. 179, 182–183] [Barthlott et al. 1997, pp. 13–14, Barthlott et al., pp. 179, 182–183]