Melocactus azureus Cactus When actively growing the plant

When actively growing the plant has thin leaves

Matucana madisoniorum Also known as Submatucana

Sansevieria kirkii 'Silver Blue'  A very attractive upright Snake Plant or Mother in Law Tongue with thick silvery blue green leaves

Care is more similar to a succulent too

Melocactus azureus Cactus When actively growing the plantMelocactus azureus Family: Cactaceae. This is a nice cephallium forming cactus with blue to blue green skin. It looks and grows like a normal cactus for several years but once it gets big enough the main plant stops growing but produces a large hairy inflorescence that continues to grow for the rest of the life of the plant. Eventually the inflorescence can be taller than the plant itself. This is more tropical than most cacti so it doesn't like cold