Where are the main production areas of Yunnan iron walnuts distributed?

They are mainly distributed in Nujiang, Kunming, Xishuangbanna, Luoping and other places in Yunnan. The fruit's shell is hard and thick, and can be used to make various beautiful and durable handicrafts; in some places, special iron walnuts are also selected for use as playing walnuts.

I. Appearance characteristics

The Yunnan iron walnut tree is a large deciduous tree, and it generally takes twenty to thirty years to bear fruit. The trunk is 10 to 20 m tall, and the thickest trunks are more than 1 m in diameter. Every year during the second and third lunar months, it is exactly the time when the iron walnut tree produces flower clusters, and a cluster of small iron walnut flowers contains dozens of blossoms. But a cluster of flowers often produces only 1 to 3 walnuts. After the flower clusters fade, the walnut tree begins to sprout and grow small leaves, and the faded flower clusters gradually grow into small walnuts. Different Yunnan iron walnut trees produce fruits of different shapes; most are two-ridged, and there are also three-ridged, four-ridged, five-ridged, six-ridged, seven-ridged, and eight-ridged ones. Of course, those with more than five ridges are extremely rare. Every year when August arrives, it is the season when the walnuts mature. After Yunnan iron walnuts mature, the outer skin splits open on its own. The walnuts inside fall from the tree by themselves. After September, the walnut tree begins to shed its leaves. In the end, all the leaves on the entire tree fall off, and it looks bare and begins to overwinter.

II. Main value

Iron walnuts are mainly used for oil pressing; among them, the large ones, as well as those with three ridges or more than three ridges, are highly prized by walnut collectors across the country for use as fitness walnuts, that is, playing walnuts. Yunnan iron walnuts, through long-term persistent rolling and playing with people's hands. Generally through the four stages of softening and brightening, rubbing red, rubbing through, and developing a porcelain-like patina, they can become natural walnut artworks that combine playing value, collection value, display value, ornamental value, and fitness value. The fitness value of playing walnuts is very great. In the circle of playing walnuts, two poems circulate. The first is: “Walnuts never leave the hand, and you will live to ninety-nine. Surpass Lord Qianlong, and the King of Hell cannot take you away.” The second is: “Sun and moon spin in the palm, and time seems to flow backward. Qi and blood surge throughout the body, when will the hair turn white?” This shows how great the fitness value of playing walnuts is, absolutely no less than ordinary physical exercise. As long as you have perseverance, it may even surpass it. As playing walnuts, compared with Ma walnuts, Yunnan iron walnuts have the advantage that their appearance is endlessly varied; conjoined ones, half-wall ones, three-ridged, four-ridged, and even those with more than five ridges can all be found. They are large in size, high in density, high in hardness, and heavy in mass, feel heavy in the hand, and are not easy to break when dropped.

Regarding Yunnan iron walnuts, in the circle of playing walnuts, a poem circulates: “Yunnan wild iron walnuts, since ancient times one tree one brand. A natural artwork of China, from ancient times to the present, who does not love it?” This shows that iron walnuts, as a branch of playing walnuts, are deeply loved by walnut enthusiasts and have research value.