This impressive lime avenue is on the Gaddesden Estate and part of the avenue lines a public footpath. In February 2010 Project volunteers recorded special trees on the estate as part of a training event.
Most of the specimen trees in the park are believed to have been planted during the 18th century which is when the Halsey family, who moved to Great Gaddesden in 1458, made a number of improvements on their land. This included building the Golden Parsonage in 1717 and Gaddesden Place, which was finished in 1774.
During our visit, we focussed our recording efforts on the Lime Avenue and found that it had originally been planted with 100 trees. Over the decades trees have been replaced when they fell so the trees in the avenue are now a variety of different ages and different genetic strains, resulting in differing growth habits.
Donald Pigott, an expert on the Tilia genus, has studied lime avenues. Many lime avenues were planted during the late 17th and early 18th centuries. There are two native species of lime, Tilia platyphyllos (Large-leafed lime) and T. cordata (Small-leafed lime). T. platyphyllos occurs as a native tree on limestone soils. Its status has been established by Rackham; other authorities still state that it may be an early introduction. T. cordata has a wider native range, although is now absent from the southern counties of England, and from pollen evidence we know that it was widespread in the prehistoric wildwood. Both native species occur as planted specimens in towns, parks and gardens. Mitchell's largest T. platyphyllos 31 x 5.8 m and largest T. cordata 32 x 6 m.
A natural hybrid between the two native species is Tilia x europaea (some authorities including Pigott use the synonym T. x vulgaris Hayne). This is Common lime, of native origin or an early introduction. Widely planted, if left unpruned it is the tallest broadleafed tree in many parts of the country. Mitchell's largest is 40 x 7 m (46 x 3.7 m at Duncombe Park, Yorks). It is often burred and densely sprout-infested at the base of the trunk and also commonly afflicted by honeydew.
The great majority of lime avenues consist of T. x vulgaris Hayne. Pigott has identified two clonal types of this species in trees planted before 1750 which have very different morphological characteristics. In Type A the trunk typically divides into 3-5 almost vertical main limbs and burrs and sprouts are common. Type B trunks tend to be less branched and burrs and sprouts are rare or absent.
In many lime avenues both types occur. At Hatfield House trees planted between 1700 and 1730 are of both types and also mixed with T. platyphyllos. Both the clones of T. x vulgaris Hayne appear to be fertile and could have produced seedlings which may have been used to fill gaps in avenues. Modern seedlings collected from under old trees of T. x vulgaris Hayne show wide morphological variations. Pigott concludes that careful selection of young trees for replanting historic avenues and other features could avoid undesirable characteristics such as heavy honeydew afflictions or burrs.
By working together, the group measured the heights and girths of the lime trees (where we could) and developed a set of guidelines on how to record avenues of trees. We also investigated different methods of approximating the girth of lime trees with dense epicormic growth at their base. This growth makes trees impossible to measure by standard methodology so we developed a set of guidelines on how to measure trees with dense epicormic growth.
Follow the footpath between the drive to Home Farm and Golden Parsonage.