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Common Names: Idiot Fruit, Ribbonwood

Scientific Name: Idiospermum australiense (Diels) S.T.Blake 

Family: Calycanthaceae – it is the only species of this family in the Southern Hemisphere


Genus: Idiospermum – from the Greek ‘idios’ "unusual", and sperma, "seed" 

Species: Australiense - Australian


Endemic to the Humid Wet Tropics of NE Queensland, between Hutchinson Creek and the Daintree River and the foothills of the Bellenden Ker Range and Mt Bartle Frere.

Native Habitat

Mature, wet lowland rainforest to 200m. Often in groups of 10 to 100 trees.


A a medium sized, evergreen tree growing to 15m.


Small and spirally arranged (a primitive feature) with creamy white tepals that change to pink and then red as they age. They are fragrant and attract beetles and thrips as pollinators.


Fruits large and globular, about 5-5.5 x 6-6.5 cm. Seeds large, about 4-5 x 5-6 cm. Cotyledons three or four, large, thick and fleshy.

Location in Garden

Native Rainforest (Bed 65i), Palace Garden (bed 65a), Middle Garden (Bed 17 and lawn 5) and Native Border (bed 103) 


Ribbonwood one of the most primitive flowering plants on the planet and until recently placed in its own family Idiospermaceae, is one of a large number of endemic primitive plants that make The Humid Wet Tropics of Queensland internationally important. The tree was first discovered in 1902 south of Cairns by a German botanist, Ludwig Diels who named it Calycanthus australiensis after comparing it to a fossil in the Dresden Herbarium. In the 1920’s Ribbonwood’s habitat was clear felled for sugar cane farming and the tree was thought to be extinct.

In 1971 it was re-discovered in very strange circumstances. A Daintree farmer found some cows that had died mysteriously and the government vet was called. An autopsy revealed several large seeds in the cow’s stomach, which were identified by botanist Stan Blake from the Queensland Herbarium as Ribbonwood which he subsequently renamed Idiospermum australiense. The offending tree had been removed by the farmer but nearby Blake found another stand of trees and seedlings.

The fruit is large and heavy and the seeds are extremely poisonous, it is one of the few fruits that no native animal or bird will eat. Given the seeds are heavy (100 grams) gravity appears to be its only dispersal mechanism. This helps explain the trees very restricted distribution. Another theory is that the fruit may once have been eaten and distributed by Australia’s ancient megafauna, most of which became 


Must See in the Garden

Recommended by the volunteers

Idiot FruitDownload the Must See in the Garden map to enjoy a self guided walk around the Garden. Created by our volunteers each month with seasonal highlights in mind.

Or simply visit the Information Booth at the Garden Shop at 10.30 am everyday and 1pm weekdays for a free guided walk!