Monvillea

M. spegazzinii -

Native to Paraquay and northeast Argentina. Characterised by many basal shoots and erect stems to 2 meters tall. Stems are an irridescent bluish-green, with usually four raised angular ribs. Areoles reside in deep recesses in the ribs, with 3 to 5 dark spines. Nocturnal flowers are red outside and white centers, borne laterally.

Needs semi-shade and to be kept above 50 degrees F. Fast growing.

Reported to contain unspecified alkaloids.