The Sobreiro Monumental (Monumental Cork Oak), also known as The Whistler Tree, is a 236 year old cork oak from Águas de Moura, Palmela, Portugal.

[1] It was voted European Tree of the Year in 2018, it has been classified as "Tree of Public Interest" since 1988 and is registered in the Guinness Book of Records as "the largest cork oak in the world".

[1][4] It was planted in 1783–1784, during the reign of Queen Maria I, and since 1820 it has been harvested over 20 times.

[1][5] The name 'Whistler Tree' comes from the whistling sound of the birds that land on its branches.

[6] In 2000 the tree was almost taken down, along with 411 other cork oaks, as an illegal urban expansion took place.