The walnut is an edible seed of any tree of the genus Juglans, best known of which is the Persian walnut - Juglans regia, although in North America you could argue that it is in fact the native Black Walnut.
All types of walnuts are quite hardy, and actually require a cold winter period in order to thrive. So anyone living in warmer climates won’t have much success with their own walnut trees.
Walnuts will start to produce nuts at around 10 years of age, give full production at 30 years and keep on producing for more than 50 years. Depending on the specific variety of the walnut tree, they can grow up to 100 feet in height.
The walnut nut!
Walnut seeds are high density source of nutrients, particularly proteins and essential fatty acids. Like other tree nuts, walnuts must be processed and stored properly. Worryingly, poor storage makes walnuts susceptible to insect and fungal mould infestations; the latter produces aflatoxin - a potent carcinogen. Mould infested walnut seed batch should not be screened then consumed - the entire batch should be discarded.
The seed kernels - commonly available as shelled walnuts - are enclosed in a brown seed coat which contains antioxidants. The antioxidants protect the oil-rich seed from atmospheric oxygen so preventing rancidity.
As mentioned previously there are two major varieties of walnuts grown for its seeds — the English walnut and the Black walnut. The Black walnut is of high flavour but due to its hard shell and poor hulling characteristics it is not grown commercially for nut production. The commercially produced walnut varieties are nearly all hybrids of the English walnut.