English-Black Walnut Nuts

There are many inter species  hybrid walnuts. Walnuts can cross with each other if there some overlap in flowering and most are very compatible with each other. Once a customer of mine planted several acres of butternuts and heartnuts. When they started to fruit, the variety of walnuts was off the charts. It was hard to say who was what. For me it started as a natural hybrid grown from seed of a Broadview english walnut. You can spot this english walnut hybrids in that the leaves look very different. I planted this seedling out and it quickly reached 60 ft. tall. I found other english walnut hybrids and planted them as well including the Luther Burbank Paradox walnut. But over time I found many of these to be incredibly shy bearing. The nuts were also incredibly thick shelled. I did eventually grow out some of the seedlings and did find some very nice crosses in terms of growth rate. Ironically the reverse cross of this is quite prolific. Nature has its surprises. 

The English-black walnut is a good choice for a strong central leader type of tree with symmetrical branching. The nuts are round and tend to crack out similar in taste to a mild  black walnut. The wood is close to english walnut although it is slight darker in color. Further selection could be done to develop more timber like trees of this cross. The nuts are incredibly thick so to improve this you would need more English walnut crossing with it and growing it out in larger numbers to find suitable crosses for seed production as well as cultivar usage. By itself, finding the most vigorous seedlings would be the most promising way to go. 

To germinate the seeds:  This species cross is similar to germinating black walnut. They need a cold period first of 90-120 days of cold and light moisture. The seeds could be put into refrigeration for the cold period and then room temperature for the sprouting to occur. This hybrid can sprout up to 2 months during the warm period as the nuts themselves can be slow to split for some reason.