Flies and Pollination

Among the plants i have here at home are several "stapeliads" (scare quotes indicates this is not considered a natural grouping).   *WARNING taxonomy follows* Stapeliads are stem succulents from the Dogbane family (Apocyanaceae) in the Milkweed subfamily (Asclepioideae). The term stapeliad used to refer to species in the former tribe Stapeliae a group that has now been lumped into the tribe Ceropegieae to address the paraphyly of its type genus, Ceropegia. To confuse things even further, this resulted in the creation of the Stapeliinae, a subtribe within the Ceropegieae which includes not only most (all?) former members of Stapeliae, but also Ceropegia. At least this is a brief, ill-informed version, the taxonomy of Ceropegia has been a complicated affair. *taxonomy ends* Stapeliads have highly derived floral morphologies that rival those of orchids. While some Orchid flowers may attract potential pollinators by sexual mimicry (Ophrys species, for example), many stapeliads are sapromyophilous (from Greek sapros rotten + muia fly + philos loving) - using chemical and visual cues the flowers mimic the brood and food sites of carrion/dung flies to attract them as pollinators. This reproductive strategy has also evolved independently in members of another, deeply divergent plant family - the Araceae. Corona of Stapelia schinzii.  The composition of scents produced by sapromyophilous stapeliads is highly diverse. A recent study by Jürgens et al (2006) has classified them broadly into four types: herbivore faeces mimicry, two types of carnivore/omnivore faeces or carcass mimicry and urine mimicry. Furthermore, given that the scent compositions of Araceae pollinated by carrion flies are fitted well by the same model, they argue for a universality to these distinct forms of the syndrome. Stapelia schinzii hails from Namibia and southern Angola. The individual  in my care flowered again just before Easter and i was able to observe interactions between the bloom and visiting flies. When attempting to reach a flower's nectaries or ovideposit on the flower a fly will often catch their proboscis or leg in a groove that has evolved to facilitate such ensnarement. In freeing themselves they dislodge the pollen. This is a common strategy for stapeliads A (possibly) green blowfly (Lucilla sericata) investigating the corona. The hairs are a form of mimetic sculpturing imitating an animal carcass. Sure enough, eggs were deposited... ...and they hatch! Note maggot by outer corona lobe at about 10  O'clock. Reference. Jürgens, A., Dötterl, S. and Meve, U. 2006. The Chemical nature of fetid floral odours in stapeliads (Apocyanaceae-Asclepiadoideae-Ceropegieae). New Phytologist 172: 452–468. http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2006.01845.x/full