Botany Rules 6: Ongoing Issues--Acacia

Acacia koa, Hawaii

    I have been writing how the rules for plant names are made and how they are changed. The rules and changes are made by people. But people rarely all agree. Controversial issues dividing the members of the International Association of Plant Taxonomists (IAPT) keep cropping up. 

    The current problem is the acacias. Acacias are trees and shrubs found in the Americas, Africa and Australia, with a few in southern Asia and on islands around the world. Historically they were in one huge genus with 1,540 species, the genus Acacia. 

    It has been clear for more than a decade that the acacias are not a single group but rather five groups of similar-looking plants. The subgroups (subgenera) of Acacia are being renamed as genera in their own right, bringing the names into line with the evidence, which is both molecular and morphological. 

    The problem was and is: which plants get to be called Acacia? 

     A proposal to the International Botanical Congress in Vienna in 2005 recommended changing how acacias are named. The proposal in Vienna gave the name Acacia to the biggest subgenus. It had to be a specific proposal because that biggest subgenus (Vachellia) does not include the very first species ever described with the name Acacia. Without the proposal, the rules require that the species in the biggest subgenus cease being Acacia species and become Racosperma species.

Acacia greggii, Arizona

    To give you a sense of scale, of the 1,540 species in the old genus Acacia, 222 are in three small subgenera that will be renamed in any event. Under the Vienna Proposal, 163 others from across the world will be renamed. Without the Vienna Proposal, 1,023 species, mainly in Australia, will be renamed. (The numbers don't add up because the Vienna Congress was in 2005 and new species have been named since Vienna.) 

    The Proposal passed. 

ant acacia, Costa Rica

    That displeased all kinds of people. Presumably many of the opponents are people who use plants that will have to get new names. However there are philosophical objections as well. Traditionalists find it undesireable to make a change so that the first plant ever validly named Acacia would cease to be an Acacia. 

    Industries and governments all over the world have a stake in the name of plants they work with. They use Acacia in their names or publicity and don't want to have to deal with their plants becoming Vachellia or Racosperma. So we have not just botanists but powerful industries and their governments affected.

    None of the acacias for which I have pictures changed their names under the Vienna decision, so I can't show an example. 

     The common names are probably not at issue. In Australia they call Acacia species wattle, and will go on doing so whatever the scientific name is. Gilia aggregata was renamed  Ipomopsis aggregata in similar split of a big genus, but it is still called scarlet gilia. Changing a scientific name does not necessarily change the plant's common name. 

acacia in Australia

     The opponents of the Vienna Proposal got the issue back on the ballot at the International Botanical Congress in Melbourne, Australia in 2011. 

     Again it passed, leaving the name Acacia with the largest, Australian, group of species. 

    There is still strong opposition. The Acacia issue will almost certainly be considered again at the next International Botanical Congress, which is in Shenzen China in 2017.  

    Most names and name changes are totally uncontested. The ongoing debate over Acacia emphasizes that people make nomenclature rules and that plant name changes can involve all sorts of people.

Comments and corrections welcome.

References 

Smith, G. F. and E. Figueiredo. 2011. Conserving Acacia Mill. with a conserved type: What happened in Melbourne. Taxon 60(5): 1504-1506.

Thiele, K. R., V. A. Funk, K. Iwatsuki, P. Morat, C-I. Peng, P. H. Raven, J. Sarukhán and O. Seberg. 2011. The controversy over the retypification of Acacia Mill. with an Australian type--a pragmatic view. Taxon 60: 194-198.

World Wide Wattle - Australian acacia website http://www.worldwidewattle.com/

acacia in Australia

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