Lepismium cruciforme (Vell.) Miq.

Stems mostly 3-5 angled, often purplish and with scalloped margins. Areoles white-hairy in the margin notches. Flowers lateral, whitish inside. Fruit more or less spherical.

SE Brazil to N Argentina

 

L. ianthothele (Monv.) Barthlott has flowers pale yellow inside.

Source: Thompson, A, ; Forbes, S.; Spencer, R. (1997). Cactaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.

kingdom Plantae
phylum   Tracheophyta
class    Magnoliopsida
superorder     Caryophyllanae
order      Caryophyllales
family       Cactaceae
genus        Lepismium Pfeiff.