Hydnora triceps

Hydnora triceps's fruits in half

Hydnora triceps is a holoparasitic flowering plant native to Africa that grows on the roots of Euphorbia dregeana. Completely lacking in chlorophyll, it depends on its host for water and nutrients. The plant structure is composed of only specialized stems, buds, and haustoria lacking any leaf-like structures entirely. It spends its life underground and only emerges to flower.

German botanist Johann Franz Drège described Hydnora triceps in 1830 after collecting it from the Northwestern Cape. It was then thought extinct for many years until rediscovered by botanist Johann Visser in 1988. It is one of four species of parasitic underground plants in the genus Hydnora.[1] Their family, the Hydnoraceae, is the only angiosperm family totally lacking leaves or scales.

Hydnora triceps is found only in the northwestern Cape and southern Namibia. Additionally, since it is entirely dependent on Euphorbia dregeana, which also seems to be its exclusive host, it is only found with a Euphorbia dregeana plant. About 10% of all the Euphorbia dregeana plants found in the regions where Hydnora triceps occurs, were parasitized.

The dominant climate where Hydnora triceps is found is semi-arid. Temperatures can range from 20 to 35 °C during the day, but can reach highs of over 40 °C. The average rainfall is 350 to 700mm (14 – 28 in).[3] The soil is extremely dry and lacking in nutrients. The major vegetation found in this area is scattered patches of grass and shrubs. Hydnora triceps is a perennial plant, and will always be associated with a Euphorbia dregeana plant.

Flowers of Hydnora triceps have chambers. The androecium consists of an antheral ring, leading down a tube, to a cushion-like stigma. The length of the sub-antheral chamber varies from 2 to 10 cm (0.8 to 4 in) in length. In an immature flower, the antheral ring is open, and pollen develops on ridges along the outside. Then as it matures, the antheral ring closes creating "pollen platforms" within. There is an osmophore, a scent producing structure, in the folds of each lobe which is heart shaped and white. The flower is rarely seen above ground, and if it is, only the very tip of it is seen protruding from the surface. Typically, it is found up to 5 cm (2 in) below the surface, and can be found by the cracks in the soil above it.

The ovary is located below the sub-antheral chamber and produces the fruits. The fruits have a tough, dark brown pericarp, which is anywhere from 1 to 10 mm thick, surrounding a white fleshy interior through which are threaded strands of minute brown seeds. The fruits can weigh anywhere from 225 to 275 g, and are 3 to 10 cm (1.2–4 in) in diameter. They taste and smell faintly of coconut, with a texture (when ripe) like a mealy apple. The fruit, technically a berry, may split at maturity. Sometimes, however, the mammals simply create a hole themselves and eat the pulp. It is not known exactly which mammals eat the fruit, or what attracts them.