In autumn the walnuts still hang green on the tree: lump after lump suspended, and once fallen, the outer skin rots away, leaving the hard shell—crack it and inside is the crinkled kernel, like a small, humble brain.

What the Green Husk Wraps Is the Kernel

On the tree, the walnut is green: a thick green husk whose juice stains the hand; tear it off and there is the hard shell, and inside the shell the kernel we know.

Strictly speaking, what we eat is not the walnut’s fruit flesh but the seed inside the nut. Green husk, hard shell, thin skin, kernel—peel through layer after layer before you reach the real thing.

— Botany Notes, self-inscription —

A green husk wraps a clever hollow;

one crack and a mountain appears inside.

A Beating and a Sunning

Walnuts ripen in autumn; when the husk turns from green to yellow and splits, they are ready to knock down. After picking, husk them while moist, then spread them out to sun, until they knock with a crisp sound and you can hear the kernel rattling inside the shell.

Undried walnuts do not keep—they mold and go off. So post-harvest handling takes more care than the picking itself: a walnut’s reputation is mostly given by those few days of sun.

Every Layer Is Material

The kernel is both food and medicine—moistening the bowels, tonifying the kidneys and nourishing the brain in materia medica records—and rich in oil, pressed as walnut oil. The woody partition between the two halves, called fenxin mu, enters medicine too.

The shells fuel fires and grind as abrasives; the green husk was once used to dye cloth. From fruit to shell, a single tree wastes nothing—things of the mountains are not used to throwing away.

• How to know it: Deciduous tree; pinnate compound leaves, leaflets large and fragrant; fruit with fleshy green husk and hard inner shell; flowers April–May.
• Season: Flowers April–May; fruit September–October; harvest when husks split, husk and sun-dry.
• Caution: Fresh husk juice stains hands—wear gloves; nuts must be thoroughly dried before storage to prevent mold and pests.

It Grows Slowly

The walnut tree is a slow one: seedlings take years to bear, which is why cultivation uses grafted stock to shorten the wait. Deep-rooted, sun-loving, and fond of deep, well-drained soil, it spreads best where the earth is deep.

A walnut tree can live decades, and the older it grows the more it bears. Those who plant it are often planting for the next generation: set it in this year, and the harvest waits many years. “A tree planted by one’s forebears” is precisely this kind of tree.

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Keywords: walnut · post-harvest sunning · fruit tree · fenxin mu