We all know what a walnut looks like but the walnut family, Juglandaceae, is a large family within the order Fagales. This order of trees is the one which includes Beeches, Birch, Oaks and Hornbeams and many more. There are two English walnuts (Juglans regia) in the park and three Caucasian wingnuts (Pterocarya fraxinifolia) and these represent just a small portion of what is called the walnut family.
There are some very interesting species within the rest of the walnut family but the tree that draws attention in the park is one of the wingnuts. It is close to the hedge along the side of the car park near the Grange Road entrance. Around June to July it is quite conspicuous due to the many fruits dangling from its branches.
The Caucasian wingnut originates from the Caucasus region between the Black sea and the Caspian sea and was introduced to Britain around 1800. The name Pterocarya is derived from the ancient Greek ‘Pteron’ for wing and ‘karyon’ for nut. The species name, ‘fraxinifolia’ means the leaves are like those of an Ash tree – Fraxinus excelsior.
Catkins start to appear on the tree in late March. The male catkins are quite short and green. The female catkins are longer, yellow to reddish and these are the ones that grow long and dangly. Once the female flowers are pollinated the fruits begin to develop and the female catkins increase in size as the characteristic wings of the fruits develop. They are all very green to begin with but by late autumn they dry out and turn brown. The fruits are adapted to be wind dispersed – not surprising with a name like wingnut, really.
The first two pictures, in the slideshow, show male catkins while the third one, I believe, shows female catkins. One of the female catkins still has the typical red styles, the tip of the female reproductive organ, which receives the pollen.
This Caucasian wingnut is much smaller than the one by the car park and is about half way down the path alongside Avenue Road.
Another small tree, this wingnut is in a line of trees alongside the small playground.
English walnuts
There are two of these trees, Juglans regia, both near the bowling green. Both trees regularly produce nice green fruits which never get the chance to ripen before the squirrels have eaten them.
Black walnut
This is the only Black walnut tree, that I know of, in the park. It is near the end of the large playground on the embankment overlooking Avenue Road. The leaves are very different to the English walnut; they look more like an Ash tree as they are a pinnate leaf with several leaflets either side of a long leaf stalk. This tree is a native of North America and likes a wet habitat, usually along river banks.
Kings Heath Park Trees 