Etymology -The genus name comes from the Greek kalumma, meaning veiled and anthos, meaning flower.
This genus is especially unique among cacti and includes one species. Stems grow to large tree-like shubs up to 26 feet (8m) high with segments between growth. Ribs are sharply angled numbering 3 or 4 with areoles indented along the edge. Spines are not especially heavy. The flowers are very distinct in that they come out looking like a new stem segment, but as it develops, the flower emerges out of the end and remains partly covered by the floral tube.