Ornithoglossum vulgare, the Karoo slangkop

The Cape poison onion or Karoo slangkop, as Ornithoglossum vulgare is commonly known, is a perennial bulbous plant that occurs widely across southern and tropical Africa. This is said to be the member of the small Ornithoglossum genus that has the largest distribution, although O. viride is also found from the Cape to tropical Africa.

This plant is poisonous to livestock, as are others of the genus. The common Afrikaans name of slangkop (snakes head), may refer to the arched manner in which the flower pedicel arches, or to the plants toxicity. Some Urginea species, also toxic, with inflorescences that may also resemble snake heads, are also called slangkop. 

The common names conferred by lay observers on plants and animals, often convey interesting details about species. People dont have to be academics to observe accurately. Some rural people with limited schooling display great versatility and ingenuity in their descriptive powers.

Still, these names are not formally established in a system, therefore often inconsistent and confusing. The scientific nomenclature is indispensable, even to amateurs dabbling in a little more than the most cursory forms of botanising (Vlok and Schutte-Vlok, 2010; www.pacificbulbsociety.org).