Biologists from The Australian National University (ANU) have named an unlikely pair of plants after Arnold Schwarzenegger and Danny DeVito, the stars of the 1988 movie Twins.

Lead researcher Emeritus Professor Mike Crisp said one of the species of Daviesia, a genus of Australian pea flowers, was much more robust than the other, calling to mind the movie about Julius and his twin brother Vincent, the products of a genetic project.

"We discover early on in the movie that the embryo split in two, but it didn't split equally -- all the purity and strength went into Schwarzenegger's character Julius, while the dregs went into Vincent, DeVito's character," said Professor Crisp from the ANU Research School of Biology.

Daviesia schwarzenegger and devito are among 131 different sub-species that Professor Crisp and his ANU colleagues have identified within the genus Daviesia, which are known as 'egg and bacon peas' due to the colours of their flowers.

Professor Crisp said Daviesia Devito was a smaller and weaker plant, while Daviesia schwarzenegger was a bigger and more robust plant.

"We also wish to honour Arnold Schwarzenegger's leadership as Governor of California in pioneering the reduction of carbon emissions, and for advising the Australian Government to do the same," he said.

The unexpected twin species are found in South Eastern Australia in the Mallee region, through South Australia, Victoria and New South Wales.

"Both species are at risk of extinction, because they appear to be confined to tiny remnant patches of bushland in a region that is largely cleared for wheat farming," Professor Crisp said.

"These plants are ecologically important members of the communities of plants in which they grow. They're nitrogen fixers, playing an important role in the Mallee region where the top soil is very denuded and the nutrients are depleted. It's essential to have nitrogen fixers to replace those nutrients."

Professor Crisp said the team's monograph, which was published in Phytotaxa and took 40 years to produce, contributed to the huge ongoing task of documenting biodiversity globally.