While biting into a walnut cake or grabbing a bag of walnuts from the shelf, the chances are that you’ve never stopped to consider the kind of walnut that you are eating. Did you know that there are 50 species of walnut tree within the Juglandaceae family and yet the walnuts we eat on a regular basis come, almost exclusively, from just two of them?
The two main varieties of walnut
Within the walnut family, the two varieties that are eaten the most are called Juglans regia, commonly known as the English walnut, and Juglans nigra, also known as the Black walnut. These two varieties alone are responsible for the vast majority of walnut cultivation, with the English walnut coming out on top as the single most cultivated walnut variety in the world.
Why do we cultivate these two varieties the most?
The English walnut is the most common variety of cultivated walnut, favoured all over the world for its large nut, relatively thin shell and mild, sweet flavour. Over the year’s the English walnut has been selectively bred to enhance its favourable characteristics, maximising yield and its profitability and making it the most popular variety for commercial production. The Black walnut, on the other hand, is a lesser cultivated variety but is still prized for its much more intense walnut flavour. Unlike the English walnut, the Black walnut has a much tougher, thicker husk and shell, making it more difficult to process and crack to get to the nut within. At the end of the day, the reasons why these two varieties are the most cultivated is because their nuts are the most sought after, they are the easiest to grow and they are the most resilient to pests.
Where did walnuts originate from?
Walnuts are widely considered to be the oldest tree food in the world, with archeological evidence showing the consumption of walnuts by humans from as far back as 8000BC. The exact origins of each walnut variety are lesser-known, with some people speculating that the English variety originated in Persia (hence its other name, the Persian walnut) while others consider Kyrgyzstan, a landlocked country bordered by Kazakhstan, to be its birthplace due to the large native walnut forests that grow there. Growing native from the Balkans to the Himalayas and southwest China, and also across much of Europe, the English walnut has adapted well to a variety of growing conditions, making it harder to trace its original heritage.
The Black walnut, on the other hand, requires more specific growing conditions, preferring to grow at the edges of rivers or streams. Originating in North America, the Black walnut variety was not introduced to Europe until the mid 16th century and required a warmer climate with plenty of fertile soil in order to thrive.
So there you have it - now you know the origin of the humble walnut. Thanks to careful cultivation there are now even more cultivars of the common English walnut variety, reducing crop times and improving the yield of walnut groves for commercial production. Want to read more on walnuts? Check out our post on Everything You Need To know About Walnuts