Hydnoraceae

Family Description

Distribution Map

Prosopanche is known from southern South America and Costa Rica. Hydnora is found in Africa and Madagascar. This is a classic example of a Gondwanan distribution. The ancestor of the two genera likely occupied Gondwana prior to the separation of that continent into Africa and South America ca. 100 million years ago. The amazing discovery of Prosopanche in Central America (Gomez and Gomez 1981) demonstrates a wide range disjunction for the genus. The taxon has been considered a new species (P. costaricensis) or conspecific with P. americana of South America.

List of Genera

Photographs

Hydnora africana

• Habit on host plant, Euphorbia mauritanica, near Worcester, South Africa. Photo by D. L. Nickrent.
• Flower connected to horizontal rhizome-like pilot root. Note the blackened and whithered perianths littering the soil nearby. Near Worcester, South Africa. Photo by D. L. Nickrent.
• Close-up of 3-merous flower. Near Worcester, South Africa. Photo by D. L. Nickrent.
• Day one flower (right) and day two flower (left), showing "bait bodies" along edges of perianth lobes. Karasburg District, Namibia. 29 December 2002, Photo by L. J. Musselman.
• Pilot root (dark) showing attachment by haustorial root to the root of the host plant (Euphorbia - light colored). Near Worcester, South Africa. Photo by D. L. Nickrent.
• Young fruit forming from inferior ovary of flower (left) and a flower bud (right) opened to show anther attachment to perianth lobe. Near Worcester, South Africa. Photo by D. L. Nickrent.
• Mature fruit, sectioned. Karasburg District, Namibia. 28 December 2002 . Photo by L. J. Musselman.

Hydnora johannis

• Flowers with ruler for scale. Ethiopia: Harar Province. Photograph by William Burger [No. 3490], 9 May 1964. Slide no. 520. archived at Kew.
• A somewhat desiccated specimen. Ethiopia: N of Midago. Photograph by William Burger [s.n.], 9 May 1964. Slide no. 4173 archived at Kew.
• Flower, sectioned longitudinally, with ruler. Ethiopia, N of Midago. Photo by William Burger. 10 May, 1964. Slide no. 4174 archived at Kew.
• Top view of flowers emerging from grassy area. Tanganyika: Kondoa District. Photograph by Roger Polhill and Paolo [no. 1139], 11 Jan. 1962. Slide no. 1959 archived at Kew.
• Flower being pollinated by an orgy of beetles! From "Sex Lives of Flowers" by Meeuse, p. 92.  Photo by Malcolm J. Coe of Oxford Scientific Films.
• Fruit sectoned longitudinally. Yemen. Photograph by Eric Danell.

Hydnora triceps

• Flower. This species is almost completely subterranean! Only the three small openings in the flower are present near the surface of the ground.
• Flowers, longitudinally sectioned.
• Fruits, showing various stages of drying after being eaten by an unknown animal. Near Port Nolloth, South Africa. 23 December 2002. Photo by L. J. Musselman.
• Fruits, beginning to dehisce. Near Port Nolloth, South Africa. 23 December 2002. Photo by L. J. Musselman.
• Fruit freshly cut fruit, pericarp has not darkened. Near Port Nolloth, South Africa. 23 December 2002. Photo by L. J. Musselman.
• Fruit sectioned, close-up, showing seeds. Near Port Nolloth, South Africa. 23 December 2002. Photo by L. J. Musselman.
• Comparison of fruits of Hydnora triceps (right) and H. africana (left), both immature. Steinkopf Road a few kilometers east of Port Nolloth, Namibia. Photo by L. J. Musselman.

Hydnora species

This may be the rare Hydnora esculenta, but flowers have yet to be seen. This poorly known species is from Berenty, a private nature reserve in southern Madagascar. Photographs by George Williams.

• Fruit with withered, black perianth still attached at the top.
• Good photo of pilot root with haustorial roots (bumps) along its length. .
• Fruit sectioned showing the parietal placentae. The pulp and seeds of the fruit are sweet and actively sought by lemurs.
• Fruit closeup showing the seeds.
• For more photographs and written descriptions (in French and English) of the Hydnora from Berenty, visit this page produced by George Williams or the Berenty website.

Prosopanche americana

• A bud just emerging from the soil. Near Cordoba, Argentina. Photo by Andrea Coccuci.
• The bud at an early stage of opening. Only the top parts of the flower emerge from the soil - the rest remain underground. Near Cordoba, Argentina. Photo by Andrea Coccuci.
• Flower, fully open, showing the dome-like, fused androecium. Near Cordoba, Argentina. Photo by Andrea Coccuci.
• Flower, with androecium releasing pollen, excavated to show the inferior ovary. Near Cordoba, Argentina. Photo by Andrea Coccuci.
• Close-up of synandrium. Lihue Calel, Argentina. 1996? Photo by J. Mauseth
• The strange flower is shown here emerging from the soil in a field in Argentina. The plant is parasitic on the roots of Prosopis, a tree in the legume family. Photo by Lytton Musselman, Argentina.
• Fruit emerging from the soil. Note the darkened remnants of the perianth at the apex of the fruit and the circumscissile dehiscence. Photo by Lytton Musselman.
• Fruit excavated to show circumscissile dehiscence. Photo by Lytton Musselman
• Pilot root with numerous haustorial roots emerging from it. Those haustorial roots that have broken off ooze white latex. Photo by Lytton Musselman.
• Prosopanche grows as far north as Bolivia and Peru. This plant was found emerging from the soil in a garden (parasitic on Solanum) in Santa Cruz, which occurs in the tropical part of Bolivia. Another photo showing the a younger open flower that was partially excavated. Photos May 2003 by Dr. Pierre L. Ibisch.
• Prosopanche fruits, from the same Bolivian plants shown above. This slide of a sectioned fruit shows the white fleshy endocarp pulp surrounding numerous seeds. Cocucci and Cocucci (1996) estimate 35,000 per fruit!). This slide, shows a close-up of the pulp being visited by numerous ants. Cocucci and Cocucci suggest that seed dispersal is endozoochorous, probably involving nocturnal mammals (rodents, foxes, and armadillos). Although ants clearly visit these fruits, it has not been documented whether they effectively disperse the seeds. Photos July 2003 by Dr. Pierre L. Ibisch.
• This Prosopanche occurs in the Braulio Carrillo National Park near the Quebrada Gonzalez station, 500 m elevation, Costa Rica. The plant is parasitic on roots of rain forest trees on the very wet Atlantic slope, quite different than the habitat of the species growing in Argentina. Although named as a new species (P. costaricensis L. D. Gómez & Gómez-Laur.), Coccuci and Coccuci (1996) consider this name a synonym of P. americana. Photo by B. Hammel.
• Prosopanche flowers sectioned. Costa Rica, Limon, Pococi, P.N. Braulio Carrillo; Llanura de Santa Clara. Barry Hammel, Paul & Hiltje Maas (No. 18037). Link goes to TROPICOS image library at MO.

Prosopanche bonacinae

• Flower attached to root. Argentina. Photo by L. J. Musselman
• Flower of this species compared to P. americana (right). Argentina. Photo by L. J. Musselman
• Older flower, with perianth dehiscing and fruit forming. Argentina. Photo by L. J. Musselman
• Young fruit. Argentina. Photo by L. J. Musselman
• Root connected to host root (smaller). Argentina. Photo by L. J. Musselman.

The Hydnora Page (L. J. Musselman, ODU). Use Netscape (not Explorer) if you wish to view all the photographs!

Hydnora on the cover of American Journal of Botany. See article by Tennakoon et al. on the vegetative morphology and anatomy of H. triceps, a hypogeous root holoparasite.  AJB 2007, vol. 94, 1439-1449.

Phylogeny

The most recent work on the phylogeny of Hydnoraceae can be found in the following publication:

Nickrent, D. L., A. Blarer, Y.-L. Qiu, D. E. Soltis, P. S. Soltis, and M. Zanis. 2002. Molecular data place Hydnoraceae with Aristolochiaceae. Amer. J. Bot. 89 (11): 1809-1817. For a PDF file of this article, click HERE.

References