Orbea variegata

Name and research material

The accepted name is Orbea variegata (L.) Haw. Historical Stapelia variegata and Ceropegia mixta, used in the 2018 study, refer to the same species. Pollination studies were conducted at the South African sites of Clifton and Scarborough, while analyses of osmophore structure used material grown in the UMCS botanical garden. [Płachno et al. 2010] [du Plessis et al. 2018] [2-WWW]

Structure and secretory tissues

The flower has five spreading corolla lobes and a distinct raised ring, the annulus, surrounding the centre. The surface is covered with papillose glandular cells. Microchannels were observed in their cuticle, and extensive structures associated with active secretion were found inside the cells. Osmophores occur on both the corolla and the ring. [Płachno et al. 2010]

Pollinators and attraction

The main confirmed pollinator was Musca domestica, with smaller contributions from blowflies and flesh flies. Insects probed around the gynostegium, and pollinia attached to their mouthparts. Floral scent contained mainly phenol, dimethyl disulphide and dimethyl trisulphide. [du Plessis et al. 2018]

Flowers hidden beneath grass still attracted flies, but visible flowers received more visits. Black models carrying natural floral scent were visited more often than corresponding yellow models. Adding spots and changing their size did not significantly alter visit numbers in the experimental arrangement used. The result separates the role of overall colour from that of characteristic spotting. [du Plessis et al. 2018]

Fruit set in the material studied

The authors observed fruits forming from one or two follicles and numerous seeds. Pollination indices differed between sites, and the conversion of removed pollinia into successful depositions was low. Individual stages of the process, visits, pollen removal, deposition and fruit maturation, were measured separately. [du Plessis et al. 2018]