This first series of photos of a cultivar of Acer davidii was seen at the Cobtree Manor Park between Aylesford and Maidstone in October. 2015. I think it is probably Acer davidii 'George Forrest'. This is still a small tree here, in its native habitat the species is a medium-sized spreading tree that can grow to 10 - 15 m.
According to Wikipedia, the leaves are 6–18 cm long and 4–9 cm broad, with a petiole 3–6 cm long; they are dark green above, paler below, ovate, unlobed or weakly three-lobed, with a serrated margin. They may turn to bright yellow, orange or red in the autumn. The flowers are small, yellow, with five sepals and petals about 4 mm long; they are produced on arching to pendulous 7–12 cm racemes in late spring, with male and female flowers on different racemes. The samara nutlets are 7–10 mm long and 4–6 mm broad, with a wing 2–3 cm long and 5 mm broad.
'George Forrest' is a cultivar of Acer davidii (subspecies davidii?) that is said to have originated in Scotland. The species was originally discovered by Pere Armand David, in 1869 and rediscovered by Charles Maries a few years later, 1878.
The species description states that samara nutlets are 7–10 mm long and 4–6 mm broad, with a wing 2–3 cm long and 5 mm broad, at nearly 180 degrees. Flowers small, yellowish, in slender, pendulous, 5-7.5 cm long, clusters (racemes); female clusters longer than male.
These particular leaves are not very serrated, toothed or lobed. Pictures on the internet appear to indicate a degree of variability! Oregon State University points out that in the species on younger plants almost all the leaves are tri-lobed, and their own plant (of the species) is nearly entirely three-lobed. One feature that appears reasonably consistent is the crimson red of the petioles, and a variable reddishness of the shoots. The young leaves are also reddish as they unfold.
The stem is greenish with white stripes. The whitish stripes, characteristic of these snakebark maples, are said to be due to waxes that accumulate in the valleys of the bark, and may therefore be quite variable, dependant upon the ebbs and flows of the wax:
The next series of photographs is of another tree, this time in Dunorlan Park, and earlier in the season, at the beginning of August. I think this could be the cultivar 'Earnest Wilson' perhaps - they do seem quite narrow and unlobed, there does seem to be a bit of a v-fold at the base of the leaves, and they are perhaps a bit greyish underneath. so perhaps I should consider this. The arching habit is quoted on some websites. If so, there should be a good orange autumn colour, not seen in 'George Forrest', but the leaves should not unfold in the early dark orange flush characteristic of 'George Forrest'.
In this case the petioles are a light reddish-pink rather than bright scarlet, and this could perhaps be due to the time of year, or perhaps 'George Forrest' isn't the right ID, and 'Earnest Wilson' is.
It was interesting to see on these ripening samaras that the area of the nutlets remain a strong green while the wings have started to colour up quite well. I also saw this pattern in the tree labelled as Acer davidii 'Serpentine', which is encouraging if it is thought to be a feature of the species.
So interesting to compare with the samaras of the tree tentatively identified as Acer rufinerve in Dunorlan Park where this colour pattern is entirely reversed.
Here is a picture of one of the main stems, showing the "white, green and brown vertical striping" and some of the horizontal break-lines in the bark that we see in some of the on-line images, unreliable as they are. On this plant, there are none of the dark purple stripes that you see in some online photos, however.
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