This forum has been looking rather lonely for a while now, so I'm throwing in a question that arises from a recent posting in the Plant Identification forum. I suspect the original poster and most other members are not very concerned with knotty nomenclatural questions, which is why this seems the more appropriate place to discuss them. The original posting was at http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=18388 POPO wanted to know the species name of the jujube. I responded with the answer Ziziphus jujuba. MichaelF responded: "Which is a synonym of Ziziphus zizyphus (L.) Karsten" This was new to me, so I started to investigate. The USDA PLANTS database and the Wikipedia article on the Jujube do indeed use the name Z. zizyphus, with Z. jujuba as synonym. But RHS Plant Finder sticks with Z. jujuba, as does GRIN Taxonomy for Plants (USDA Germplasm Network) and many other sources. Obviously the answer as to which is the correct name must lie somewhere in the International Code of Botanical Nomenclature (ICBN). The latest version, the "Vienna Code", has just appeared online at http://www.ibot.sav.sk/karolx/kod/0000Viennatitle.htm There is no mention of Ziziphus in the appendices 'Nomina generica conservanda et rejicienda' or 'Nomina specifica conservanda et rejicienda'. A bit of googling revealed that there had been a proposal in 1999 to conserve the genus name with the spelling Zizyphus and gender feminine. This would have had the effect of making the name Z. zizyphus a tautonym (i.e. genus and species names identical and therefore not allowable under the Code). But this proposal was apparently rejected by the Committee for Spermatophyta, a group with wide powers in such matters. Unfortunately, just now I don't know the reasons they gave for rejection because I cannot access their report online unless I pay $U12 to the publishers of the journal Taxon, or visit a major botanical library. It is quite possible that the Committee stated there was no need for conservation as Zizyphus and Ziziphus are merely orthographic variants. This case appears to be an almost exact parallel to that of the tomato, for which the names Lycopersicon esculentum Mill. and Lycopersicon lycopersicum (L.) Karsten had both been used. However, the first of these is conserved against the second in the list of 'Nomina specifica conservanda et rejicienda' (this conservation is superfluous when the tomato is reclassified under Solanum, as S. lycopersicum). It seems to me that the spirit of the Code tends toward discouragement of names like Ziziphus zizyphus. So, I am still no closer to the answer. Can anyone (Michael??) explain one way or the other?
Hi Tony, You've got the important one - that the proposal to change the genus spelling to 'Zizyphus' (widely used, but not the original spelling used by Miller) was rejected; the result therefore is that the original Ziziphus used by Miller is retained (or reinstated), and the combination Ziziphus zizyphus is therefore valid, not being a tautonym. The tomato case differs in that the proposal for conservation of Lycopersicon esculentum was accepted. The far greater economic importance of the species would have been a very significant point in retaining Miller's later, though very widely used name.
