What we grow - Biodiversity



The walnut tree (Also called “white walnut tree”, “common walnut tree” or “real walnut tree” – Juglans regia – Family Juglandaceae, probably “Juglans” is a Latin term coined in honor of Jupiter: “Jovis glans” “acorn of Jupiter” since among the ancient Romans the walnut tree was consecrated to the king of the gods, while “regia”, which means “royal”, reveals that the tree was introduced in the West by the kings of Persia), is the representative of the best known and most important genus from an economic point of view, especially for the production of the fruit (Seed), called walnut. Some archaeological finds indicate that walnuts were already used as food 9000 years ago, while the first written records date back to Columella and Pliny the Elder, who in his publication “Naturalis historia” testifies, instead, that the import of walnuts into Europe from Asia Minor was the work of the Greek colonists (VII – V century B.C.), while in America (XVII century A.D.) by the English colonists. There is evidence on its presence already from the Tertiary era in Europe, in fact, it is hypothesized that following the glaciations, some specimens managed to arrive in the Mediterranean basin, in fact the range of the walnut tree in the Quaternary age extended from the peninsula Balkan to Central Asia (Currently, the walnut tree is a plant introduced in almost all temperate regions, but its original diffusion in the wild is relatively more limited). Today there are still pure walnut woods in Kyrgyzstan (Tien Shan Mountain Range). 


The walnut tree is vigorous, deciduous and broad-leaved, characterized by a solid, tall, straight trunk with a majestic posture and has robust roots initially taproot and with expanded and very superficial maturity. It can reach 30 meters in height and is very long-lived (There are many centuries-old specimens). The leaves are large and light green, compound and alternate. It is a monoecious plant in which the male flowers are gathered in pendulous aments, 10-15 centimeters long, with numerous stamens, which appear on the branches of the previous year before the appearance of the leaves. The female unisexual flowers open from mixed buds after the male ones, solitary or gathered in groups of 2-3, appear on the new sprouts of the year, at the same time as the leaves. The fruit is a drupe, composed of the fleshy, fibrous exocarp (Hull), blackens when ripe and frees the woody endocarp, that is the seed, the real walnut, consisting of two valves that enclose the kernel with a high content of lipids. Flowering occurs in April and ripening takes place in September-October.


The properties of walnuts are numerous, being rich in phosphorus, potassium, magnesium, calcium, copper (Necessary for the synthesis of hemoglobin and for hormones), zinc (An important immunomodulator) and iron, as well as a good amount of fatty acids omega 3, useful for keeping sugars under control and excellent for heart health, in fact, have a cardiotonic action and are a valid therapeutic ally in conditions of mental fatigue, as well as lowering cholesterol. Walnut is properly a nervous system tonic and possesses anti-anemic, antispasmodic, sedative and anti-inflammatory properties. The presence of magnesium, which has an anti-stress, anti-inflammatory, pain-relieving, sedative and anti-edema action. The walnut tree is widely cultivated, as well as for food, also for its multiple uses, such as the construction of furniture, being a hard wood, pleasantly veined and with a characteristic color. Fresh or dried walnuts can be consumed directly as nuts, or used in cuisine to flavor salads, desserts but also to prepare jams. Walnuts are also included in the composition of numerous processed foods: bread, cheese, honey, liqueurs, sauces, etc. Furthermore, walnut oil is also extracted from the walnut, while the “Walnut wine”, as well as the walnut hull, is used in the preparation of the numerous types of “Nocino”, generally drunk as digestives. Walnut shells can be used as fuel, while green walnuts harvested in June are used to make pickled walnuts.


The common walnut tree (Juglans regia) tolerates weakly basic and calcareous soils, while the black walnut tree (Juglans nigra) needs fresh and slightly acidic soils. The walnut tree is easy to cultivate, but the soil on which it is grown must be rich in organic matter, with particular attention to the water supply in June, because, in the event of a lack of water, the fruits will be small. Water is also essential because it is the moment of flower induction (The flowers of the following year). Late frosts or droughts affect the next year’s harvest. The cultivated trees begin to produce in the fifth-sixth year, and enter full production from the 25th year to the 70 years. After harvesting, the hull covering the woody shell must be removed immediately and then left to dry to allow for long-term storage. Through the roots the walnut tree produces the “juglone” which, due to allelopathy, is toxic to other species and does not allow its growth near the plant.