Pingao research

A new name and genus for pingao

By Peter de Lange
E: pdelange@doc.govt.nz

New Zealand has just lost another endemic genus. Pingao, the golden sand sedge beloved of many New Zealanders, and voted the most popular native plant last year by the annual NZPCN poll, has now been moved to a mostly South African genus.

Pingao, one of the key sand binders of the New Zealand sandy beaches and dune systems, has long been known in New Zealand as the sole representative of the endemic genus Desmoschoenus. Desmoschoenus was proposed by Joseph Hooker in 1853 to accommodate the species which had previously been known as Isolepis spiralis. Pingao was first drawn to the attention of western botanists when it was collected by Joseph Banks and Daniel Solander from several locations in the eastern North Island. They proposed to call this distinctive sedge “Scirpus frondosus” but as with most of their Endeavour voyage discoveries the name was not formally published by them. So it was the French, under the command of Dumont d’Urville, who officially “recognised” the species when the renowned French botany professor Achille Richard described pingao as Isolepis spiralis in 1832 based on specimens forwarded him by d’Urville (Richard 1832).

However, Hooker appreciated that the species was misplaced in that genus and, on the basis of the distinctive paniculate, globose, interrupted, multi-flowered and densely whorled leafy spicate inflorescences, proposed the genus Desmoschoenus (Hooker 1853). Two years later, in apparent ignorance of Hooker’s move, Ernst Steudel proposed a new genus Anthophyllum, and the name A. urvillei for the same species, using the same material collected by the French. Desmoschoenus, the older name by some two years, had priority, and by and large pingao has been known by that name ever since.

Although Desmoschoenus has been in almost constant use for the last 150 or so years, there has not been universal support for the genus. For example, in 1878 Johann Boeckeler legitimised the Banks and Solander manuscript name Scirpus frondosus, and in 1916 George Druce proposed Scirpus spiralis for pingao. Interestingly, in 1996 two South African botanist published a paper in the New Zealand Journal of Botany, the significance of which seems to have been completely overlooked in this country: Browning & Gordon-Gray (1996) noticed that the ovules of pingao were held within a gynophore, a small cup-like structure. Gynophores are the defining character of a largely South African genus, Ficinia. They also noted that pingao was not really that different from other South African species of Ficinia. Perhaps New Zealanders didn’t fully appreciate the importance of this paper because our only species of Ficinia, F. nodosa, has little resemblance to pingao. Anyway, for whatever reason, New Zealanders seem to have ignored what this paper was driving at, and Desmoschoenus remained intact.

In 2003 I made a chromosome count of pingao, noting that it had 2n = 30 chromosomes but, because there are no other species in that genus and the relationship of Desmoschoenus to other members of the Cyperaceae was “seemingly” unclear, there was little I could say about it. At about the same, time I provided material to the University of Auckland for sequencing as part of their nrDNA ITS study into the New Zealand Cyperaceae. The initial results showed that pingao consistently sat with Ficinia nodosa, albeit that both sat on a clade and both species occupied very long branches. We assumed that this result was caused by what is known as “long branch detraction syndrome”. Also, because there were no further ITS sequences available for Ficinia, and because Desmoschoenus and Ficinia nodosa are unusual singletons in the New Zealand flora we didn’t explore the matter further. Alas, like so many well intentioned DNA studies, those results were never published but our sequences were loaded up on GenBank (the international, publically available database of DNA sequences) so that they could be used by other people worldwide.

As a result, in 2007 Dr Muthama Muasya of the University of Cape Town, South Africa, and world expert on Isolepis got in touch. It transpired that during his doctoral research on Isolepis he had studied Desmoschoenus, and his molecular work consistently showed that it was consistently nested within Ficinia (see Muasya et al. 2001, 2009a,b). He had wanted to reduce Desmoschoenus to Ficinia but his then northern hemisphere supervisor told him he shouldn’t do this because “New Zealand people would be upset”. At this stage, having just seen what had been done to Chionohebe, Hebe, Heliohebe, Leonohebe and Parahebe at the urging of mostly northern hemisphere botanists, I couldn’t help but see the irony of this and said so. As a result Muthama and I agreed to merge Desmoschoenus with Ficinia, but I stressed this needed to be done properly, with all the lines of reasoning published in one place, and in New Zealand literature. After all, Desmoschoenus is a popular and important New Zealand taonga, so our people need to see why changes like these happen, not have to hear about it second hand, or be reduced to fossicking around in overseas journals (many of which are difficult to access).

Our results, published in the New Zealand Journal of Botany 48 show why we believe Desmoschoenus is better treated as Ficinia, and we provide the necessary combination in that genus for the species – F. spiralis (A.Rich.) Muasya et de Lange. In that paper (Muasya & de Lange 2010) we use data pooled from two molecular markers, and a sampling of 18 Ficinia, 20 Isolepis, one Hellmuthia and one Scirpoides. Interestingly, Scirpoides (as Holoschoenus) was the one genus Hooker felt Desmoschoenus was closest too. The paper also illustrates the diversity of Ficinia, and we include those species to which Desmoschoenus is closely allied. We further argue that, aside from the all important gynophore, the presence of a condensed and spirally arranged paniculate inflorescence is another key feature shared by the two genera. As for Ficinia nodosa? It occupies a very distant position toward the base of Ficinia but, if you look at the back of its inflorescence critically and compare it to the back of a pingao inflorescence, you will see a remarkable resemblance between the two.

The unusual position of Ficinia spiralis as the sole endemic of the genus to be found outside South Africa, may seem remarkable. However in the New Zealand Flora there is one other parallel, Bulbinella, which is a genus shared by both countries but not found in between (although Bulbinopsis comes pretty close to it).

Postscript

Dr Brian Murray (pers. comm.) kindly counted the chromosomes of Ficinia nodosa – New Zealand’s only other species in the genus, finding that it too had 2n = 30. While I’d like to draw some nice conclusions about that result, alas I can’t because to date only that species and F. spiralis have been chromosomally investigated. It would be interesting indeed to see the chromosome numbers of the other endemic South African species.

References

Browning, J; Gordon-Gray, K.D. 1996. A gynophore in Desmoschoenus (Cyperaceae). New Zealand Journal of Botany 34: 131–134.

Hooker, J.D 1853. The Botany of the Antarctic Voyage of H.M. Discovery Ships Erebus and Terror in the Years 1839-1843.Vol. 2. Flora Novae-Zelandiae Part I. Flowering Plants. Lovell Reeve, London.

Muasya, A.M.; de Lange, P.J. 2010: Ficinia spiralis (Cyperaceae) a new genus and combination for Desmoschoenus spiralis. New Zealand Journal of Botany 48: 31–39.

Muasya, A.M.; Simpson, D.A.; Chase, M.W.; Culham, A. 2001. A phylogeny of Isolepis (Cyperaceae) inferred using plastid rbcL and trnL-F sequence data. Systematic Botany 26: 342–353.

Muasya, A.M.; Simpson, D.A.; Verboom, G.A; Goetghebeur, P.; Naczi, R.F.C.; Chase, M.W.; Smets, E. 2009. Phylogeny of Cyperaceae based on DNA sequence data: current progress and future prospects.  Botanical Review 75: 2-21.

Muasya, A.M.; Vrijdaghs, A.; Simpson, D.A.; Chase, M.W.; Goetghebeur, P.; Smets, E. 2009. What is a genus in Cypereae: phylogeny, character homology assessment and generic circumscription.  Botanical Review 75: 52-66.

Richard, A. 1832. Voyage de Decouvertes de L’Astrolabe, Botanique. Essai d’une Flore de La Nouvelle-Zelande. Paris.

This page last updated on 23 Sep 2012