Walnut tree – Jüglans regia L.
Description of walnut tree:
Jüglans regia L. (Magnificent walnut tree) Walnut trees – Juglandaceae The common walnut, or walnut tree, is the national tree of the Hungarians, originating from Persia, but cultivated in Hungary since ancient times. Its leaves are known in the trade as folia juglandis and the shells of its unripe fruit as cortex juglandis fructus. The walnut tree can reach a height of 20 m. Its bark is grey and cracked, its wood hard and brown in colour. Its leaves are oddly winged. Its flowers are undemanding, small, green and monoecious, i.e. there are separate male and female flowers on the same tree. The male flowers form drooping spikes and the female flowers are 2-3 at the top of the ephemeral shoots. The flower produces a stone fruit, which contains an oil-rich seed. The walnut tree flowers in May, when it is green, before the foliage is fully developed. The leaves and all the green parts have a pleasant, strong, heady fragrance and a pungent astringent, bitter astringency. When dried, both the taste and the smell disappear. Unfortunately, the bark beetle is a common pest in our country, which destroys the fruit. 
Occurrence:
It is native to Persia. It is commonly found from the Caucasus through India to Japan. It is planted everywhere in our country, and in some places it has gone wild.
Nut leaf tea:
Its leaves, fresh and dried, are used as a blood-purifying tea, used against glandular diseases and scrofula; also for poultices, washing; nut-leaf tea is used as a foot soak and to enhance hair growth. The sap of the green skin of the fruit blackens in the air. It is used, as is the bark, to make a beautiful long-lasting brown dye. The skin of the fruit was formerly used for dyeing hair, and is now used as a wormicide. The unripe fruit is boiled in sugar and put into brandy to strengthen the stomach. When ripe, the seeds contain a lot of oil, which is first green and then pale yellow, odourless and pleasant-tasting. Walnut oil is used to cure skin diseases and is important in painting because it dries quickly.
Taking walnut leaves:
The leaves should be picked before they are fully grown, in the month of June, and then dried suddenly. Therefore, the leaves should be dried in the sun so that they do not turn brown, because browned leaves are worthless (spread out in a 4-5 finger thick layer, moved once a day, because not only will they be more beautiful, but they will dry faster). If carelessly handled, walnut leaves can easily turn black and become worthless. As the nuts dry, they lose their balsamic smell and astringency and acquire a succulent, astringent flavour. Of course, the fruit is also harvested, the unripe fruit must be picked in July, but today only the dried leaves are a commercial commodity, and even that is only sold to a limited extent. The unripe fruit is used for preserving and for making liqueurs. The ripe fruit is used on its own or in cakes.
Active ingredient:
Tannic acid, juglandin alkaloid and very little essential oil. Source: Béla Páter, The Wild Herbs Dr. Ferenc Darvas and Dr. Gyula Magyary-Kossa,Domestic medicinal plants, their production, marketing, effects and medicinal uses