Rhodocactus stenanthus

Rhodocactus stenanthus is a species of cactus that is endemic to Brazil. First described as Pereskia stenantha, it was transferred to Rhodocactus in 2016. Like all species in the genus Rhodocactus, and unlike most cacti, it has persistent leaves. In its native locality, it is sometimes used in hedges.

Description
Rhodocactus stenanthus grows as a small tree or a shrub, usually reaching 2 – high, occasionally 6 m, with trunks to about 15 cm in diameter in large specimens. The young twigs, 4 – thick, have variable numbers of stomata. Mature stems develop grayish-brown bark. Like all species of Rhodocactus, and unlike most other cacti, R. stenanthus has persistent leaves, that are variable in shape and size. The very largest are up to 15 cm long and 9 cm wide, but more usually they are 7 – by 4 –. The fleshy leaves are often folded upwards along the midrib and have short petioles, 2 – long. The areoles bear leaves (brachyblast leaves) along with spines. The areoles on the twigs have up to seven spines, those on the trunks may have about 40, each up to 5 cm long. The flowers are orange-red on the outside and pink inside and are borne in terminal or axillary inflorescences of 1–15 forming dense clusters. Individual flowers are urn-shaped (urceolate) and do not open widely, reaching only 1 – across. The fruits are variable in shape, 3 – long, green or yellowish-green when ripe, and contain many glossy black seeds. In its native habitat, R. stenanthus flowers in the spring and summer, from November to April.

In all features other than the flowers, R. stenanthus closely resembles R. bahiensis. The shape, colour and orientation of the flowers suggests they may be pollinated by hummingbirds.

Taxonomy
The species was first described by Friedrich Ritter in 1979 as Pereskia stenantha. Molecular phylogenetic studies from 2005 onwards suggested that when Pereskia was broadly circumscribed, it was not monophyletic, and consisted of three clades. In 2016, the genus Rhodocactus was revived for one of these clades, with P. stenantha included as R. stenanthus.

Distribution and habitat
Rhodocactus stenanthus is native to northeast and southeast Brazil. In the state of Bahia, it occurs in caatinga (subtropical and tropical dry shrubland) at altitudes of about 400 –.

Conservation
Rhodocactus bahiensis has been assessed as Least Concern, with no major threats. is a common species with a stable population trend and regenerates well after disturbance.

Uses
In the areas where it grows, local people may plant Rhodocactus stenanthus in hedges.