In 1825 the trunk was measured at 21 feet (6.4 m) in circumference at ground level, reducing to 12 feet 2 inches (3.71 m) at a height of 5 feet (1.5 m) from the ground. It measured 67 feet (20 m) in height with branches extending up to 45 feet (14 m) to give a canopy covering 19 English square poles of land (574.75 square yards; 480.56 m2).[2]
After this time the tree declined, partly due to age and partly due to parts of it being removed as souvenirs.[2] By the mid-19th century it had become common for Scottish men to own a snuff box that incorporated a fragment of the Wallace Oak together with part of a tree said to have been planted by Mary, Queen of Scots at Holyrood Palace, part of another tree under which she is said to have watched the Battle of Langside and a portion of the rafters of Alloway Auld Kirk (made famous by Robert Burns).[5]
By 1851, Jacob George Strutt drew it for his Sylva Britannica, many of its branches had been removed and it was described as "a melancholy torso, bald and frail, with its limbs hacked off by relic hunters, like Wallace's by the hangman". The tree fell during a storm in 1856. Its timber was reputedly used to make two regency-style tables.[3] John McAdam commissioned an elaborate frame made from the oak in 1867 which he intended to be used to contain letters about Wallace at the National Wallace Monument.[6]
Acorns from the Oak were raised to saplings by Daniel Johnston Baron Officer at the Elderslie Estate; one of the saplings was planted at Fountain Gardens in Paisley[7] where it still stands.