The Paper-bark Maple - Acer griseum
To commemorate the 21st anniversary of the Dulwich Society, a Paper-bark Maple was planted in the Picture Gallery garden in 1985. So far it has reached a height of about 4.5m , which should eventually more than double.
Its English name arises from the way that the outer layers of the reddish bark peel away, around the trunk, in horizontal strips. Most Acer species have simple palmate leaves like those of Sycamore, though a number lack the palmate structure. The leaves of Acer griseum differ in that they are compound leaves formed of three leaflets. When the new leaves unfold in spring they show a sequence of colours during the process of greening, in which their photosynthetic pigments are synthesized. Conversely in autumn the foliage attains a spectacular deep crimson prior to leaf fall. Attractive throughout the year in bark and foliage, it is considered to be one of the most outstanding maples, well worthy of its Award of Garden Merit by the Royal Horticultural Society.
Although many species of Acer can be assigned to their genus on the basis of their leaves, it is the fruit that that is the reliable diagnostic. The familiar structure of two fused winged samaras, as seen in the fruit of sycamore is characteristic. However the viability of the Acer griseum seed is reported to be low, and vegetative propagation is difficult. Grafting has been found to be effective, and the outcome is that some Acer griseum trees in cultivation are likely to be on root-stocks of a different Acer species.
Acer griseum was collected in China by Pere Paul Farges, a French missionary, and by Augustine Henry, an Irish plantsman, in the nineteenth century. It was brought to England in 1901 by Ernest Wilson, who collected living material for the Veitch Nursery. Wilson is credited with the introduction of about 1,200 species into horticulture and is remembered in the Ernest Wilson Memorial Garden in Chipping Camden. Acer griseum has been found to occur naturally in a wide area of central China, growing in mixed forest at an elevation of 1,500 to 2,000m. Currently its natural population is reported to be fragmented, small, in decline and listed as endangered.