Hyobanche research

Hyobanche (Orobanchaceae) is a small genus of holoparasitic plants (i.e., plants that parasitize other plants) native to southern Africa. Its common name is “Cat nails” because of the way the stigma curves out of the corolla tube in several species to resemble a cat’s claw. It’s also called “inkbloom” because it turns black upon drying, and it was used in the colonial days for an ink substitute. The plants were ground into a fine powder and suspended in liquid.

Most species are in South Africa. In addition, two species are found in either Lesotho (H. rubra) or Namibia (H. barklyi). Most of the species were described in the early 1900s, but little was known about them until the recent work done by Wolfe and colleagues (Wolfe & Randle 2001, 2004; Morawetz et al. 2010; Wolfe 2013; McNeal et al. 2013).

Hyobanche is a cool genus for many reasons, but my favorite is that it seems to be an analog to a “canary in a coal mine” for assessing the health of an ecosystem. Parasitic plants, in general, tend to increase biodiversity of ecosystems. One only finds Hyobanche in systems that are relatively undisturbed by humans. Occasionally, I’ve seen Hyobanche species in urban gardens or along roadsides, but it mostly occurs in ecosystems that have native vegetation and soils. Another cool fact about Hyobanche is that it has no roots. Well, actually, there is one root as soon as the seed germinates, but that immediately finds a host plant to latch onto and then develops into a special organ of attachment (the haustorium), which functions in nutrient transfer from host to parasite. What one finds underground, below the inflorescence, is an extensive rhizome system. The rhizomes are covered in modified bracts that can form secondary haustoria. When a host root touches the bract, it can form a haustorium to capture the root. Thus, each Hyobanche plant can be attached to multiple roots – sometimes from the same plant, but often from multiple species of hosts simultaneously.

Check out the Hyobanche blog post I did in October 2011. I have a photo gallery and video link there.

Check out the photo gallery from some of my field seasons to get an idea of what Hyobanche is like in its natural habitat.

Species of Hyobanche

H. atropurpurea (Western Cape)
H. barklyi (Northern Cape and Namibia)
H. fulleri (Kwazulu-Natal – along the coast)
H. glabrata (Western Cape, Northern Cape)
H. robusta (Eastern Cape – along the coast)
H. rubra (Eastern Cape, Western Cape, Northern Cape, Lesotho)
H. sanguinea (most of South Africa)
H. thinophila (Western Cape – along the coast; described in 2013)

Literature cited

McNeal JR, Bennett JR, Wolfe AD, Mathews S (2013) Phylogeny and origins of holoparasitism in Orobanchaceae. American Journal of Botany 100, 971-983.

Morawetz JJ, Randle CP, Wolfe AD (2010) Phylogenetic relationships within the tropical clade of Orobanchaceae. Taxon 59, 416-426.

Wolfe AD (2013) Hyobanche thinophila (Orobanchaceae), a new species from the Western Cape of South Africa. Phytotaxa 85, 56-60.

Wolfe AD, Randle CP (2001) Relationships within and among species of the holoparasitic genus Hyobanche (Orobanchaceae) inferred from ISSR banding patterns and nucleotide sequences. Systematic Botany 26, 120-130.

Wolfe AD, Randle CP (2004) Recombination, heteroplasmy, haplotype polymorphism, and paralogy in plastid genes: Implications for plant molecular systematics. Systematic Botany 24, 1011-1020.

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