Amongst broadleaved trees Juglans has a similar Holarctic range, descending to the West Indies; so has Aesculus, were it not lacking in Europe; it becomes tropical in South America and Malaya.
In Casuarina, Juglans and the order Corylaceae, the pollen-tube does not enter by means of the micropyle, but passing down the ovary wall and through the placenta, enters at the chalazal end of the ovule.
The common walnut (Juglans regia) grows in Great Britain.
The white walnut (Juglans alba) or hickory is common in North America, and is very tough, hard and elastic. The black walnut (Juglans nigra) is also native to America.
I harvest walnuts (Juglans regia) from within the woods and from trees overhanging local footpaths.