Thursday, 15 November 2012

Autumn leaf colours

Leaf coloration is unpredictable. Last year the Witch Hazels (Hamamelis species) in my garden turned a brilliant scarlet in late October; this year they were disappointingly drab.
In the USA the maples of Vermont and Maine are famous for their autumnal brilliance and here in Byfield their relatives are putting on a good show. The falling leaves of the Field Maple Acer campestre had, on 14th November, spread a golden carpet across the edge of the cricket pitch. Sadly the leaves of its close relative, Sycamore (Acer pseudoplatanus), are disfigured with the aptly-named Tar Spot.

Sycamore  affected by Tar Spot

  This is caused by a fungus Rhytisma      acerinum and affects all sycamores hereabouts. It seems to do little harm to the tree but some horse deaths have been attributed to eating the affected leaves.

Field Maple is undoubtedly native to Britain whereas Sycamore has always been scorned as an alien. However, Ted Green, in an excellent article in British Wildlife (Vol. 16, part 2), casts doubt on this assumption. Pollen in ancient peat deposits is often used to establish the presence of a particular plant but it seems that Sycamore pollen and that of Field Maple are virtually impossible to tell apart, so perhaps it has been here all along. If so we should afford it more respect.

Naturally John Clare got in his six penn'orth:

                             In massy foliage of a summer green
                             The splendid Sycamore adorns the spring
                                                 Clare's Rural Muse 1835

Clare is buried under a Sycamore at Helpston.

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