Tree of Knowledge, Memorial in Barcaldine, Queensland, Australia

The Tree of Knowledge is a memorial in Oak Street, Barcaldine, Queensland, built on the site of a Corymbia aparrerinja ghost gum killed by poisoning in 2006. Rows of long wooden slats hang like a curtain around a pale, bare-branched trunk, forming a rough dome beside the street and low buildings. A dark sign on a post in front of the trunk reads "Tree of Knowledge" and "Barcaldine".

The ghost gum Corymbia aparrerinja stood in front of Barcaldine railway station, where shearers on strike met in 1891; the strike was called off on 15 June that year. On 9 September 1892 the Queensland Labour Party manifesto was read at its foot, leading to the formation of the Labor Party in Queensland. The tree was added to the Queensland Heritage Register on 21 October 1992, poisoned with glyphosate in 2006 and declared dead on 3 October 2006; its remains were removed on 29 July 2007.

Before it was called the Tree of Knowledge, the ghost gum was known as the Alleluia Tree because the Salvation Army held meetings beneath it. Shearers and union delegates then gathered in its shade to hear the 1892 Labour manifesto read aloud. The tree was added to the Queensland Heritage Register on 21 October 1992.

The memorial stands on Oak Street in front of the former Barcaldine railway station, where strikers once rallied as trains brought police and non-union labour. The original tree's remains were removed on 29 July 2007; the timber memorial that replaced it opened on 2 May 2009. Look for the dark sign with the red, white and blue logo naming the Tree of Knowledge.

The suspended elements are arranged to recreate the shape of the former tree, which disappeared over time. This spatial representation allows visitors to stand beneath the replicated canopy as if the tree were still present.