Astrophytum

The species of the genus Astrophytum usually grow individually with spherical to columnar green shoots and reach heights of up to 1.5 meters. The shoots are often densely covered with fine white tufts of hair, but sometimes they are completely bald. There are four to ten (rarely three) very noticeable ribs that are not divided into cusps. The large areoles stand close together, but do not merge. The spike is variable. Thorns may be present or may be missing entirely.