Background Document to the Acacia Vote

At the International Botanical Congress (IBC) in Vienna in 2005, the 'decision' was taken to conserve the name Acacia with a new type from Australia (Acacia penninervis) which replaced the original African type (Acacia nilotica). This effectively restricts the name Acacia to the group of largely Australian wattles, by excluding its use for the widespread tropical true acacias.

We are challenging this 'decision' and, since the name Acacia has usage well beyond the scientific community, we would like to include in the challenge all those who wish to help build a strong case to overturn the Acacia retypification at the next IBC meeting in Melbourne in 2011.

One of the less recognised facts about the Nomenclature Section meeting in Vienna (2005) was the success of the 'no' campaigners to the proposal to retypify Acacia with an Australian species. The votes of many tropical Herbaria were included in the 54.9% majority vote not to accept the proposal to change the type of Acacia, despite a highly organised campaign by supporters of the proposal. However, at the start of the session which dealt with this issue, a requirement for a 60% majority vote to overturn the retypification proposal was suddenly introduced. This contravenes normal operating procedures at such meetings, which require instead a 60% majority to change the Code and a simple 50% majority for all other matters (which should have included the Acacia retypification proposal).

Since there was a clear majority (54.9%) against change in Vienna, we feel there is no need to reopen the arguments for and against the retypification as part of this challenge. Instead, we believe that the best and most simple approach is to keep the challenge to a legal one, concerning only the imposed requirement for a 60% majority to overturn the retypification at that meeting.

Anyone who is concerned about the Acacia retypification issue, lay person or professional, is asked to vote. We need very substantial support to indicate the extent of dissatisfaction with the way this matter was handled in 2005 and also to act as leverage when submitting our challenge for Melbourne, 2011.

Clarification about what was voted on in Vienna

There has been much confusion about what was actually voted on in Vienna. This confusion was caused by the mixing up of issues to do with the rules of how plants are named (i.e., the remit of the Vienna Nomenclature Section) with taxonomic issues (i.e., whether Acacia is recognised as one large genus with a number of subgenera, or is split into various separate genera).

Dealing with the taxonomic issues first. There is now overwhelming evidence that Acacia (in the traditional broad concept of the genus including a number of subgenera) will be split and recognised as separate new or reinstated genera. In fact, the largely Australian block of wattles is now found to be taxonomically located far away from the rest of Acacia, embedded in another legume tribe (a taxonomic category between genus and subfamily). These conclusions are convincingly supported by much multidisciplinary and cross-institutional research. Also, the nearly 207 species of Acacia belonging to subgenus Aculeiferum are already being recognised as a separate reinstated genus Senegalia in much of the Neotropics, although this has not been formalised for the African species.

The nub of the retypification proposal, however, was not a taxonomic one. Supporters built a case around the fact that Australian wattles involved far more species than tropical true acacias. Conserving the name Acacia with a new type from Australia allowed the name Acacia to be used for the bulk of species in the genus in the traditional broad sense, i.e., the c. 1000 largely Australian wattles, instead of for the c. 161 true acacias (i.e., excluding the Senegalia group). When recognised as a separate genus the wattles would otherwise have had to go by the name of Racosperma, which is the correct name for Acacia subgenus Phyllodineae at the genus level.

The 'yes' campaigners in Vienna cited precedents for retypification, e.g. the legume genus Hedysarum. The type species of Hedysarum was found to belong in a different genus (Sulla, with 7 species) to the rest of Hedysarum (comprising 200+ species). To avoid massive upheaval, with numerous name changes, the name Hedysarum was thus conserved for the bulk of the species, with a new type species being designated. This retypification was done for the best of reasons and in an exemplary way. In the case of Acacia this precedent was followed a lot less scrupulously and without apparent good reason. The wattles had already been published with new names in Racosperma by Les Pedley some years beforehand, so there was no confusion as to where they should go once separated from the rest of Acacia. Also there is no good reason why the type should be moved from the c. 161 true acacias (i.e., Acacia subgenus Acacia), which remain after all other generic elements have been separated, because there is no potential nomenclatural confusion in this case.

The debate, therefore, about which divisions of Acacia are recognised at what taxonomic level is quite independent from the central issue dealt with in Vienna, that of the type being moved from Acacia (i.e., Acacia subgenus Acacia), to the wattles, simply because the latter group comprises a larger number of species. The retypification initiative took little heed of the many other factors involved, i.e., social, cultural, ecological, economic, demographic or historical concerns that needed to be debated prior to a vote for or against the retypification.

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