Parasitic Plant Connection

Hydnoraceae C. Agardh.


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.

Hydnoraceae Distribution Map

List of Genera

Photographs

Hydnora abyssinica

Hydnora africana

Hydnora esculenta

Hydnora johannis

Hydnora longicollis

Hydnora triceps

Hydnora visseri

Prosopanche americana

Prosopanche bonacinae


The Hydnora Page (L. J. Musselman, ODU).

IJPS Hydnora cover

Bolin, J. F., E. Maass, and L. J. Musselman. 2009. Pollination biology of Hydnora africana thunb. (Hydnoraceae) in Namibia: brood-site mimicry with insect imprisonment. Int. J. Plant Sci. 170: 157–163.

cover AJB Hydnora

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 & Classification

This family contains two genera, Prosopanche (S. and C. America), and Hydnora (Africa and Madagascar). As with Balanophoraceae, Cronquist and Takhtajan differed in their classifications of this family. Cronquist placed it in Rosidae in Rafflesiales, Takhtajan in Magnoliidae with Rafflesianae.  Both were incorrect with regard to a relationship with Rafflesiaceae.  Takhtajan was closer in placing the family in Magnoliidae, for indeed molecular data place Hydnoraceae in Piperales (Nickrent et al. 2002, pdf HERE). This was later confirmed by Naumann J, et al. (2013. Single-copy nuclear genes place haustorial Hydnoraceae within Piperales and reveal a Cretaceous origin of multiple parasitic angiosperm lineages. PLoS ONE 8:e79204).

The APG3 (2009) classification recognized five families in Piperales: Aristolochiaceae, Hydnoraceae, Lactoridaceae, Piperaceae, and Saururaceae.  The Angiosperm Phylogeny Website by Peter Stevens shows a tree with Hydnoraceae sister to Aristolochiaceae plus Lactoridaceae, however, the text lumps these groups, recognizing subfamily Hydnoroideae.  In APG4 (2016), three families were recognized, Saururaceae and Piperaceae, with Hydnoraceae and Lactoridaceae lumped into Aristolochiaceae. The justification for the lumping derives from the work of Naumann et al. (2013) who used 19 genes as well as Massoni et al. (2014, Increased sampling of both genes and taxa improves resolution of phylogenetic relationships within Magnoliidae, a large and early-diverging clade of angiosperms. Molecular Phylogenetics and Evolution 70:84–93) who used a 12 gene dataset. All of these molecular studies detected the same six groups that correspond to the above five familes plus one other; a part of Aristolochiaceae (subfamily Asaroideae) is distinct. It is worth noting the the topologies of the Naumann and Massoni phylogenetic trees do not agree with regard to the six groups, plus the introduction of Hydnoraceae lowers bootstrap values at key nodes. It seems that instead of lumping the shrubby Lactoridaceae (1 species, L. fernandeziana), the morphologically bizarre holoparasite family Hydnoraceae, and Aristolochiaceae (9 genera 465 species according to Mabberley 2008), it would be simpler to simply elevate Asaroideae Burnett to the rank of family and leave the rest of the classifications alone! This new family (Asaraceae) would contain Asarum (ca. 80 spp.) and Saruma (1 species, S. henryi). As I have argued (as have others), it is important for members of our field to recognize the history of names when considering re-classifications and to introduce the least number of disruptions. For these reasons, I continue to recognize Hydnoraceae as a distinct family in Piperales.

References



Last updated: 04-May-18 / dln