The Brimmon Oak in Wales narrowly missed out on being crowned 2017 European Tree of the Year, and the Woodland Trust hopes a tree from the UK could go one step better next time round.
The Tree of the Year competition, supported by the People's Postcode Lottery, is asking people to nominate trees for four shortlists representing England, Scotland, Wales and Northern Ireland, which the public will then be able to vote on.
From the four country winners one will be chosen to represent the UK in the Europe-wide contest.
Tree lovers are being asked to nominate a tree with a link to a historical figure or event, a tree at the heart of a community or one which is just well loved.
As it launched the new search for the country's best trees, the Woodland Trust called on the Government to act on proposals which could lead to increased protection for some of the country's most famous and ancient trees and woodlands.
In this year's European Tree of the Year contest, the giant Brimmon oak in Newtown, Powys, which was saved from being felled for a bypass, was runner-up with 16,203 votes.
Poland's entry, the Oak Josef, which sheltered a Jewish family hiding from the Nazis and featured on a Polish banknote, came top in the public poll.
Jill Butler, Woodland Trust ancient tree adviser, said: "We came so close to claiming the European crown this year, which is incredibly heartening to see such support and love for a UK tree.
"With the recent positive news about improved protection we hope everyone nominating a special tree this year may soon see better protection in place."
Each of the four winning trees will receive a tree care award of up to £1,000 for arboricultural surveys or other maintenance, interpretation or even to support a community event in celebration of the tree.
Clara Govier, head of charities at the People's Postcode Lottery, said: "We are delighted that players are able to support this wonderful celebration of the nation's special trees and what they mean to people.
"For the second year running money will be available to directly benefit the trees."
The Woodland Trust will reveal four shortlists in September for England, Scotland, Wales and Northern Ireland for the public to vote on before one UK winner is crowned.
:: To nominate a tree until the end of July, people can visit www.woodlandtrust.org.uk/treeoftheyear