The genus Juglans includes walnuts of different cultivated species, such as Juglans regia or European walnut tree, that is cultivated for example in California and Oregon; J. nigra or black walnut in the United States; J. Cinerea, cultivated in Arkansas, Georgia and Canada, etc.

The varieties that are cultivated in Europe belong to the species Juglans regia. There are early and late varieties. Within each group of varieties there is also a distinction between fruit of soft shell or hard shell, distinguishing them in subclasses, whether they are intended for consumption or for oil extraction. The walnuts which have a greater quantity of oil are less appreciated as dessert and they have a very hard and full up shell. Dessert walnuts must have a soft or semi soft shell, with a certain appearance and rather thick.

In the market we find Spanish, French and American varieties. Among the French varieties stand out Franquette, Grandjean, Marbot, Corne, Mayette, Parisienne, Chaberte, Candelou, Meylannaise, Ronde de Montignac, etc. The most adapted Californian varieties, of Mediterranean climate, are Serr, Hartley, Vina, Tehama, Payne, Pioneer, Chico, Amigo and Pedro. Walnut trees of Spanish selection are Mayor, Onteniente, Baldo II, Carcagente, Cerdá, Escrivá and Villena.

There are other varieties cultivated in the world which have diverse importance since they represent their countries of origin, such as Adams, Chambers, Chase and Spurgeon in Oregon, Sorrento, Malizia, Bleggiana and Feltrina in Italy, Sisibel in Rumania, Geisenheim in Germany, As-1 in Chile and Rego in Portugal.

Some walnut varieties:

" Chico’
It is a small walnut that requires severe pruning to obtain good sizes. The colour of the edible part is very good. The tree is also small and erect. It is very productive and of early harvesting in California.

" Corne’
The fruit is of average size and very tasty, but the edible part is difficult to remove. The tree is very vigorous and easy to form, with a tendency to loose the leaves. It has a good productivity, although of slow fruition and late maturation, in October. It is of French origin and cultivated in Dordoña.

" Franquette’
The fruit is of good quality, thick, tasty and easy to remove. The tree is of average vigour and easily formed. It has good productivity and fast fruition, maturing in the middle of October, since it is of late maturation. It is original from the Valley of the river Isère (France).

" Grandjean"
The fruit is of average to very small size, with good taste and easily removed. The tree is vigorous, easy to form and with a tendency to loose the leaves of the base. It has good productivity, slow fruition and quite early maturation, during the first fortnight of October. Its origin is the region of Sarlat (Dordoña, France).

" Hartley"
The quality of this fruit is high, the colour of the edible part is excellent, of great size and conical shape that makes it easy to recognize the fruit. The tree is vigorous. It has high yields from the 12th year. Concerning the period of harvesting, it is of mean season. It is the Californian variety par excellence.

" Marbot"
The fruit is quite thick. The tree is of average vigour, easily formed. It has good productivity and fast fruition. It is of early maturation, from the end of September until the beginning of October. It has French origin and it is cultivated in the north of Lot and the south of Corrèze.

" Mayette’
Fruit of great size, tasty and easy to remove. The tree is very vigorous, of average productivity and quite slow fruition. It matures during the second week of October. Original from Tullins (Isère, France).

" Parisienne’
Thick and very tasty fruit, easily removed from the shell. The tree is very vigorous and easy to form. The maturation is quite late, in the middle of October. It is of French origin and it is cultivated in Isère, Vercors.

" Payne’
This walnut is of mean-small size and the edible part is of pale colour. The tree is vigorous and rounded. The fruit is harvested early, maturing in the middle of September in areas such as California.

" Pedro’
The nut’s shell is attractive because of its size and general appearance, but the kernel quickly darkens after the harvest. The tree is of average vigour and of very early production onset. It was obtained from the breeding program of Davis (California), where the harvest is from the middle to the end of the season.

" Vina’
The nut is of such a quality as to be consumed with the shell, of average size and similar in shape to "Hartley". The colour of the edible part is pale. The tree is of small or medium size and its shape is similar to " Payne’, of hanging growth habit. It was obtained in the breeding program of Davis; it is interesting because of its high productivity. It is from early to middle season.