Inspection for Newton's apple tree

Isaac Newton's apple tree, the Magna Carta tree and the Tolpuddle Martyrs' tree will all feature in a mass survey of ancient organisms to be carried out by the National Trust.

As many as 40,000 ancient oaks and other species are to be inspected and appraised by the Trust, the most important organisation for ancient trees in the UK, in a three-year assessment of their condition.

There are so many because the Trust's land holdings are enormous – they include more than 25,000 hectares of woodland, 200,000 hectares of farmland and 135 landscape and deer parks.

Isaac Newton's apple tree at Woolsthorpe Manor in Lincolnshire has been regarded as a national treasure for more than 300 years. It is believed to have inspired Newton with the "notion of gravitation" in 1665, after he watched an apple fall to the ground.

Bearing a rare variety of apple, Flower of Kent, the tree fell over in 1820 but is still growing well.

The Magna Carta yew tree, at Runnymede in Berkshire, has been famous for even longer. It is 2,000 years old and now measures 9.4 metres (31ft) wide. Growing in the grounds of the ruined Priory of Ankerwycke, it is said to have witnessed the swearing and sealing of the Magna Carta, Britain's first charter of freedom, by King John in June 1215. It is also said to be where Henry VIII met Anne Boleyn in the 1530s.

The Tolpuddle Martyrs' tree at the village of Tolpuddle in Dorset is the site of the landmark trade union meeting in 1834 which became a historic symbol of the struggles of the emerging labour movement. The leafy sycamore is likely to have started its life in the 1680s.

"Trees play such an important part in shaping our landscapes and reflecting our history that we need to make sure that the ancient trees in our care and the next generation to follow them can be enjoyed by everyone," said Ray Hawes, the Trust's head of forestry.