It is a genus of plants, generally succulents, native to the arid region between northern Mexico and the southern United States.

Their growth is slow and culminates with flowering, as they develop a floral stalk, taller than the leaves, which blooms, bears fruit, and dies in the same year.

They require a semi-dry climate, with mild/warm temperatures, and full sun exposure is very important.

They can be mistaken for cacti, aloes, or sedum due to their similar appearance, but they are different genera within different families.