Trichocereus bridgesii 'Monstrouse'
Given the common name in German Frauengluck or Women's Joy this small compact growing cactus has been in cultivation for many years and that common name is always a source of amusement for those who view the smooth cylindrical segments with their distinctive cleft for the first time. "Oh I see...."
it was formally known as Echinopsis lageniformis and may be given a further taxonomic shift given the current advances in plant molecular DNA.
The lower sections of this cactus have quite long spines which make repotting or weeding close by a minor problem but it is otherwise very hardy and decorative.
I grow some in larger pots so it has more room to show off its interesting form.
