Grafton in northern New South Wales is often labelled Australia's jacaranda capital, but a gardens curator believes Brisbane should hold the title.

Ross McKinnon, former curator of the Brisbane Botanic Gardens, said the first jacaranda tree planted in Australia was in Brisbane.

"We pre-date Grafton by 70 years, as the first jacaranda was planted in 1864 in the city's botanic gardens," he said.

The bright purple flowers become part of the scenery in Brisbane every October. ( Supplied: Josephine England )

Each year Grafton holds a jacaranda festival, laying claim to also being home to Australia's largest jacaranda tree, which reaches 30 metres high.

But Mr McKinnon said Grafton would not have the trees if Brisbane had not received the seeds first.

Ducklings sit among the jacarandas at the University of Queensland. ( Supplied: Genevieve Worrell )

"In the 1850s Queensland was sending wheat and grain to South America," he told ABC Radio Brisbane's Craig Zonca.

"On returning, they would unload at Kangaroo Point cliffs' wharfs and the first curator of the gardens, Walter Hill, would row across the river and exchange seeds and plants with visiting sea captains.

"A visiting sea captain from South America gave Walter Hill the first jacaranda, which he planted at the rear of the city botanic gardens in 1864."

Original jacaranda trunk on show

Under the Jacaranda was painted by R Godfrey Rivers in 1903. ( Queensland Art Gallery: R Godfrey Rivers )

In the 1980s the majority of that original jacaranda was blown over.

"I kept a section of the trunk, which now resides in the Museum of Brisbane in City Hall," Mr McKinnon said.

"The jacaranda is also immortalised in one of Queensland's most famous paintings, called Under the Jacaranda, which was painted in 1903 by R Godfrey Rivers.

"You can see the painting today at the Queensland Art Gallery."

What about Grafton?

Mr McKinnon said Grafton would "more than likely" have grown its original jacaranda trees from seeds from Brisbane.

"Botanic gardens at the time gave out seeds and plants that they collected from around the world to other gardens," he said.

"Early plants may have also come into the Sydney Botanic Gardens.

Smaller jacaranda trees are still being planted in suburbs throughout Brisbane. ( ABC Radio Brisbane: Jessica Hinchliffe )

"Either way, Brisbane has far more jacaranda trees than Grafton will ever have."

He added that once again the northern state had come out on top.

"It's like the State of Origin … Queensland wins again."