The Tree of Knowledge was a tree in Barcaldine, Queensland, Australia, which was regarded as the birthplace of the Australian Labor Party (ALP). This was because the town was the headquarters of the 1891 Australian shearers' strike where policy and decisions were made. It was a 200-year-old Corymbia aparrerinja ghost gum.

It is said that in 1891 a group of protesting sheep shearers founded the Australian Labor Party under the tree. Meeting records of shearers striking for better conditions show they were held at the main strike camp at the edge of the town on Lagoon Creek. Non-union labour would arrive in the town by rail where they were met by the striking shearers. These impromptu meetings arose at a Cabbage Gum tree near the station where the strikers attempted to rally union members to their cause and block non-unionists. In 1892, at the foot of the tree, the Manifesto of the Queensland Labour Party, a foundation document of the Australian Labor Party, was read out.

In 1991, the tree was found to be suffering from dieback. In an act of vandalism, the tree was poisoned with glyphosate (a main ingredient in the herbicide RoundUp) in 2006. An arborist declared the tree dead on 3 October 2006. The ALP offered a reward of A$10,000 for any information that will help identify those responsible.

The remains of the tree were removed on 29 July 2007. According to a Queensland Government release the tree is undergoing a process of wood preservation and the remains of the tree – 7 metres tall and 2 across – are being transferred to a special preservation facility. The tree was successfully cloned in 2008 by workers at the former Queensland Department of Primary Industries.

Several cuttings propagated from the tree before its death are now growing in Barcaldine. A clone of the tree has also been planted at the Ecosciences Precinct in Brisbane.

On April 19, 2011 Prime Minister Julia Gillard joined ACT Chief Minister Jon Stanhope at the National Arboretum Canberra in a ceremonial planting of a tree grown from an original cutting of the ‘Tree of Knowledge’.

A new memorial on the site of the remains of the original tree and costing about A$5M was officially opened on 2 May 2009. The memorial won The Lachlan Macquarie Award for Heritage Architecture and a National Commendation for Public Architecture at the 2010 National Architecture Awards of the Australian Institute of Architects.