1. Walnut group: walnut and iron walnut.

Walnut (Latin scientific name walnut? L.), commonly known as walnut. Trees, up to 20-25 meters; The trunk is shorter than other tree species and the crown is broad; The bark is grayish green when it is young.

It belongs to Juglandaceae. Deciduous trees, with a height of 10 ~ 20m and an age of over 100 years. Distributed in southwest China and other places. The hard shell of fruit can be used to make various beautiful and durable handicrafts; In some places, large iron walnuts are chosen as fitness balls.

2. Juglans mandshurica group: Juglans mandshurica, wild walnut, hemp walnut, Keppel walnut and heart-shaped walnut.

Juglans regia It belongs to Juglans and Carya of Juglandaceae. Deciduous trees, more than 20 meters high; Branches are swollen and the crown is oblate; Bark is gray with shallow longitudinal cracks; Young branches are covered with short hairs. The odd-numbered pinnate compound leaves born on the germination strip can reach 80 cm long, the petiole is 9- 14 cm long, the lobule is 15-23, the length is 6- 17 cm, and the width is 2-7 cm. The distribution area is located in temperate zone, and some areas can go deep into the northern edge of subtropical zone.

Wild walnut, alias hickory. Belongs to Juglans of Juglandaceae, deciduous trees or small trees; The main difference from other species in this genus is that the leaflets are densely pubescent when they grow up, and there are stellate hairs below them; The fruit is long and drooping.

Walnut is a variety of walnut. Walnut belongs to Juglandaceae, a deciduous tree with pinnate leaves. Endocarp is hard, wrinkled and yellowish brown. The fruit is harvested around a thousand years ago, the outer skin of the fruit rots, and the inner fruit is rinsed, dried and cleaned, which is what people call "walnut".

Wild silkworm originated in Japan and was introduced to China in 1930s. Liaoning, Jilin, Shandong and Shanxi are all planted. Also known as Keppel Walnut, Butt Walnut, Ghost Walnut and Japanese Walnut.

Heart-shaped walnut is also called Ji walnut. The shape of this tree is similar to that of Keppel Walnut, and the main difference lies in the fruit. This species is native to Japan and was introduced to China in 1930s. Now Liaoning, Jilin, Shandong, Shanxi, Inner Mongolia and other provinces have a small amount of cultivation.

3. Black walnut group: black walnut.

Black walnut includes 16 tree species, which are distributed in North America and Latin America. Among them, the most economically valuable tree species is the eastern black walnut (J.nigra), which is widely distributed in the eastern half of the United States and southern Canada. Nuts are the largest among 16 tree species, and wood is the best, which is used to make fine furniture and plywood.

Walnut, also known as walnut and peach, belongs to Juglandaceae. Together with almonds, cashews and hazelnuts, it is known as the world-famous "four dried fruits". Walnut kernel is rich in nutrition, with more fat and carbohydrate per 100g protein 15 ~ 20g. It also contains calcium, phosphorus, iron and other trace elements and minerals, as well as carotene, riboflavin and other vitamins. It's good for the human body. It is one of the nut foods deeply loved by ordinary people.

Generally, it is as high as 3-5 meters, with grayish white bark, shallow longitudinal crack, flaky pith and thin tips of young branches (2-year-old branches are often hairless). There are also 20-25 meters high, with shorter trunks and wider crowns than other species. Bark is grayish green when young, grayish white when old, and shallow longitudinally. Branchlets glabrous, shiny, peltate glands, grayish green, and later brownish.

Extended data:

Growth habit

Walnut likes light, cold resistance, drought resistance and disease resistance, adapts to the growth of various soils, and likes fertile and humid sandy loam, water, fertilizer and sunshine. At the same time, the requirements for water and fertilizer are not strict, and it is not suitable for pruning after defoliation and before germination, which is easy to cause bleeding. Suitable for most land growth. Calcareous soil is common in deep soil on both sides of the valley.

Therapeutic value

First, reduce the risk of depression.

Walnuts are rich in omega-3 fatty acids, which can reduce the risk of depression, attention deficit hyperactivity disorder (ADHD), cancer and Alzheimer's disease.

Second, reduce the risk of breast cancer.

Eating 2 ounces of walnuts a day is unlikely to cause breast cancer and tumors.

Third, reduce the risk of diabetes.

Women who eat nuts five times a week have a nearly 30% lower risk of developing type 2 diabetes.

Unsaturated fat in nuts is beneficial to insulin decomposition.

Fourth, reduce stress.

Walnut oil in walnuts can reduce the static blood pressure, and the change of eating habits can better help our body cope with external pressure.

References:

Baidu encyclopedia-walnut