The plant commonly known as the Starfish Flower belongs primarily to the genus Stapelia, a group of perennial succulents native to Southern Africa. It is also frequently referred to as the Carrion Flower, a name it shares with relatives in the Apocynaceae family, such as Huernia and Orbea. Its structure is defined by leafless, fleshy stems that are typically four-angled and grow in clumps, giving the plant a unique, almost cactus-like appearance. The flowers are the most striking feature, notable for their five-pointed, star-like shape and leathery texture.
The Distinctive Odor Profile
The Starfish Flower smells like decaying organic matter, specifically resembling rotting meat or carrion. The odor is purposefully offensive to the human nose, which perceives the scent as a strong signal of decomposition. Some people also detect notes similar to spoiled fish or even fecal matter, depending on the particular species of Stapelia.
The intensity of the smell is highly variable, depending on environmental factors and the age of the bloom. The fragrance can range from subtle to overwhelmingly foul. The odor is typically strongest on warm, sunny days and during the initial phase of the flower’s opening, when the plant is actively attempting to attract its specialized pollinators. As the flower ages, the emission of volatile compounds tends to diminish.
The Pollination Strategy of Carrion Flowers
The reason for this repulsive fragrance lies in the plant’s highly specialized method of reproduction, a process known as sapromyophily. This strategy involves attracting carrion-feeding insects, primarily various species of flies, to facilitate pollen transfer. The plant does not offer a reward of nectar, instead relying on a complex deception that tricks the insects into visiting the flower.
The Starfish Flower is a master mimic, using not only smell but also visual cues to imitate a fresh carcass. The flowers often display colors like deep reds, purples, and mottled browns, mimicking the coloration of decaying flesh. Furthermore, the surface of the petals is sometimes covered in fine hairs or a velvety texture, which resembles the fur or hide of a dead animal. Female flies, fooled by the sight and smell of this false carrion, are compelled to land and lay their eggs on the flower.
As the fly moves across the flower’s surface, it inadvertently picks up the plant’s pollinia, which are small packets of pollen. When the fly visits a second flower, it deposits the pollinia, thus achieving cross-pollination. The eggs the fly lays, however, are doomed, as the flower provides no actual sustenance for the hatching larvae. This one-sided interaction is an example of a deceptive pollination system, where the plant receives its benefit without giving anything in return.
Volatile Compounds Responsible for the Scent
The foul smell is created by the emission of specific volatile organic compounds (VOCs) that are chemically identical to those released during the natural breakdown of animal tissue. Among the most significant are sulfur-containing compounds, such as dimethyl disulfide and dimethyl trisulfide. These molecules are particularly effective at signaling decomposition to insects that specialize in locating carrion.
The aroma is compounded by the presence of biogenic amines, which are nitrogen-containing compounds. Two prominent examples are putrescine and cadaverine, which derive their names from putrefaction and the Latin word for corpse, respectively. The precise combination and ratio of these sulfur compounds and amines create the distinctive, multi-layered stench that successfully mimics different stages of decay, ensuring the Starfish Flower attracts the specific insects required for its survival.