Stapelia leendertziae has sapromyiophilous flowers–that is, its flowers are pollinated by flies. Sapromyiophilous flowers have evolved convergently in many families of flowering plants. They usually have large scent-emitting flowers that are coloured red or purple. These characteristics mimic the food and brood sites of carrion and dung flies. Johnson and Jürgens (2010) examined the scent compounds of sapromyiophilous flowering plants (and one fungus). They found that Stapelia leendertziae flowers emitted 31 different compounds, most of which contained sulfur. The compounds included dimethyl disulphide and dimethyl trisulphide, resulting in a scent that was remarkably similar to that emitted by dead rats (which end up being a different set of compounds than the more general “rotten meat”). Other plant species studied by Johnson and Jürgens emitted scents that also corresponded to fly-attractants, including dog faeces, horse dung, and the previously-mentioned rotten meat. Each species had its own specific set of scent compounds, these correlating with the types of flies that were seen visiting the flowers. In the case of Stapelia leendertziae, both blow flies (Calliphoridae) and flesh flies (Sarcophagidae) were observed visiting the flowers. Flies from both of those taxa are thought to consume and deposit their eggs (or hatched maggots, in the case of Sarcophagidae) on carrion.
Stapelia leendertziae flowers are nicer to look at than to smell. As you can see from today’s photo, the petals are dark red (Bruce Brethauer calls them liver-coloured), velvety, and rugose (wrinkled). The corolla forms a bell-shape that can reach 12 cm in length. The Flora of Zimbabwe cites bell-stapelia as one of the common names for the species. Most sources, however, use Leendertzi’s carrion-flower. I suppose large bell flowers are an easier sell than the stench of rotting flesh.
Stapelia leendertziae is commonly grown as a potted plant, but it is rare in the wild. It grows on rocky, shallow soil in Swaziland and northeastern South Africa. Since Stapelia pollinators can travel large distances to find individual flowering plants, members of this genus tend to be widely-scattered in the landscape. Stapelia leendertziae has dark green succulent stems that grow close to the ground. For the above reasons, finding carrion plant in its natural habitat is challenging unless it is in full flower. When in flower, simply follow the flies–and hope that you are heading towards a Staperlia leendertziae rather than a dead rat.