In this genus, the species number 11. They have slender, long, more or less prostrate, with nocturnal , and are natives of S. America.
Monvillea Cavendishii. S. Brazil, N. Argentina and Paraguay. This plant has slender, dark green with 9 obtuse ribs, which are somewhat warty. The areoles are small and whitish; radial spines number 7 to 9, and central spines 1 to 4. The plant is free flowering and bears white flowers.
Monvillea rhodoleucantha. A plant of easy cultivation requiring half shade. Very free flowering, and the flowers are very attractive, with pink outer petals and white inner petals. The areoles are small, whitish passing to brownish; radial spines number 6 or 7, centrals 1 to 3; all spines are at first yellowish-brown, changing to greyish, with a dark point.