The genus Crassula is one of the most diverse succulent genera, varying from tiny moss-like annual plants to 2m tall succulent trees like Crassula ovata. Belonging to the Crassulaceae family, there are more than 300 Crassula species of which approx. 150 are found in southern Africa, where they are widespread but concentrated in the semi-arid winter-rainfall areas. The centre of distribution of this genus is in southern Africa, but they extend beyond Africa into Europe, America, Australia, New Zealand and the southern islands. The name Crassula is the diminutive of the Latin crassus which means thick or fat, referring to the fleshy nature of the genus as a whole. This popular genus offers an extensive array of sizes, growing forms and textures making them perfect for landscaping, rockeries, windowsill plants or to be grown in containers. They can also be grown indoors as house plants. Those that make excellent house plants are the glossy leaf varieties. Crassulas, given a rich, well-drained medium will grow fast and luxuriantly.

Crassula columnaris, synonymously known as Crassula mitrata and commonly known as Khaki Button or Khakibutton in English and Koesnaatjie in Afrikaans, is a South African endemic species found in the Eastern Cape, Northern Cape and Western Cape provinces. Crassula columnaris is a dwarf, compact, perennial or biennial succulent with single short erect stems 1,5-6 cm tall in which the grey green to brownish leaves are rounded, fleshy, broader than long, arranged in 4 closed ranks, the leaves are in-curved and so closely packed over each other as completely to hide the stem.