Recent phylogenentic studies of Crassulaceae indicate that Aichryson is closely related to Monanthes and Aeonium (both genera are also largely endemic to the Canary Islands).
The garden maintains a focus on indigenous plants of Schleswig-Holstein within a broader representation of plants from around the world, including special collections of South African succulents and plants from the Atlantic islands, as well as Adromischus, Aizoaceae, Aristolochia, Campanulaceae, Crassulaceae, Cuscuta, Passiflora, Plumbaginaceae, and Vitaceae.
The adult flies from July to mid-August and the larvae feed on Sedum and Orostachys (Crassulaceae).
Similar in appearance to the "jade plant" Crassula ovata (family Crassulaceae), P. afra has smaller and rounder pads and more compact growth (shorter internodal spaces, down to 1.5 mm).