The Tree That Built the Silk Road — Korea's Mulberry and Its Thousand Uses

 The Tree That Built the Silk Road — Korea's Mulberry and Its Thousand Uses

For several hundred years, the Chinese Empire guarded this tree with the kind of intensity normally reserved for military secrets.

The knowledge of how to raise silkworms, how to feed them the leaves of this specific tree, and how to unravel the cocoons into thread — all of it was a state secret. Exporting silkworm eggs or mulberry seeds was punishable by death. The monopoly on silk production funded dynasties. Silk traveled west along the trade routes we now call the Silk Road, arriving in Rome at prices so extraordinary that Roman senators debated banning the fabric as a drain on the treasury.

The secret eventually escaped, as secrets do. Byzantine monks smuggled silkworm eggs out of China hidden in hollow walking staves, sometime around 550 CE. The knowledge spread. But for centuries, this tree — 뽕나무, the white mulberry — was the biological foundation of the most valuable trade network the ancient world had ever seen.

It doesn't look like much in April, when the leaves are just coming out. It looks exactly like what it is: a medium-sized deciduous tree leafing out in spring. But the history embedded in those leaves is considerable.

 The Tree: 뽕나무 (Morus alba)

**Korean name:** 뽕나무  

**English common name:** White Mulberry  

**Scientific name:** *Morus alba* L.  

**Family:** Moraceae (뽕나무과)  

**Fruiting season:** June – July  

**Height:** up to 15m  

**Native range:** China; cultivated throughout East Asia, now naturalized worldwide

*Morus alba* is a deciduous tree native to northern China, cultivated in Korea for well over a thousand years — primarily for sericulture, the raising of silkworms. The silkworm *Bombyx mori* feeds almost exclusively on mulberry leaves, and white mulberry leaves are its preferred food. Without this tree, the Silk Road doesn't exist.

The leaves are variable to an unusual degree — on a single tree, you may find simple oval leaves, three-lobed leaves, and five-lobed leaves growing simultaneously. This variability confused early botanists and led to multiple species being described that turned out to be the same tree in different growth stages. The leaves are bright green and slightly glossy on top, paler beneath, with a toothed margin and a slightly rough texture.

The flowers are small and inconspicuous — the tiny clustered structures visible in these photos, appearing with the new leaves in spring. Male and female flowers are typically on separate catkins on the same tree. The fruit that follows — 오디 in Korean — is a multiple fruit, like a blackberry in structure, ripening from white to pink to deep red-purple in early summer.

 Silk, Silkworms, and Korean History

Korea's relationship with mulberry cultivation and silk production goes back at least to the Three Kingdoms period, roughly 1,700 years ago. Historical records show that sericulture was practiced across the Korean peninsula during this era, and mulberry orchards were a standard feature of the agricultural landscape.

During the Joseon dynasty, silk production was considered important enough that the royal court maintained dedicated mulberry orchards and the queen herself performed ceremonial silkworm-rearing rituals each spring — a tradition that linked the ruler's household directly to the agricultural and economic foundations of the kingdom. The ceremony was called 친잠례, and it was as much political symbolism as practical activity: the queen demonstrating, by handling silkworms and spinning thread, that the court understood and honored the labor that produced the dynasty's wealth.

Mulberry cultivation was so integral to Korean rural life that 뽕밭 — mulberry fields — became a byword for rural landscapes generally. There's a classical Chinese four-character idiom, 桑田碧海 (상전벽해 in Korean), literally "mulberry fields become blue sea" — meaning total transformation, the complete change of circumstances over time. The idiom made it into Korean because mulberry fields were as familiar a landmark as anything in the countryside.

 What Koreans Ate and Healed With This Tree

뽕나무 is one of those plants where Koreans historically used every part — and in this case, each part was used for something different.

**오디 (the fruit):** Ripe mulberries were eaten fresh, made into wine, fermented into vinegar, and dried for winter use. 오디주 — mulberry wine — is still made in Korea today, particularly in regions where mulberry orchards remain. The fruit has a sweet-tart flavor, stains everything it touches a deep purple-red, and has the distinction of being legitimately nutritious — high in vitamin C, iron, calcium, and resveratrol, the same antioxidant compound found in red wine that attracted so much research attention in the 1990s.

**상엽 (the leaves):** In Korean traditional medicine, dried mulberry leaves — 상엽 — were used to clear lung heat, relieve eye redness and irritation, and treat fever. They were also used for headaches and dizziness. Modern research has confirmed that mulberry leaf contains compounds including 1-deoxynojirimycin (DNJ) that inhibit carbohydrate-digesting enzymes, reducing the rate at which sugar enters the bloodstream after meals. This is directly relevant to blood sugar management, and mulberry leaf extract is now sold as a supplement in several countries for this purpose.

**상백피 (the root bark):** The dried root bark — 상백피 — is one of the more important materials in traditional Korean and Chinese pharmacopeia, used to clear lung heat and relieve cough and wheezing. Modern research has identified bioactive flavonoids and Diels-Alder type compounds in mulberry root bark with anti-inflammatory and antimicrobial properties.

**상지 (the young branches):** Dried young twigs — 상지 — were used to treat rheumatic joint pain and improve circulation to the extremities.

This is not a plant where one part was medicinally active and the rest ignored. The whole tree was used, and each part had its own application.

 오디 Season

If you're in Korea in late June and early July, mulberry season is worth knowing about. The ripe fruit falls easily from the tree and stains the ground beneath dark red-purple — if you see an inexplicable purple stain on a path under a deciduous tree, look up. There's probably a 뽕나무 above you.

The fruit is best eaten directly from the tree when fully ripe — deep red to purple-black, soft, intensely sweet with a slight tartness. Slightly underripe fruit (still reddish-pink) is more tart. Overripe fruit ferments on the tree and drops.

Children in Korean rural areas have historically known mulberry season the way children everywhere know which trees and bushes on their routes to school produce something worth eating in summer. 오디 stains fingers and mouths purple and was informally understood to be good for you — a folk nutritional knowledge that turns out to have been accurate.

 Finding It in the Field

The photos here show 뽕나무 in early spring, just as the leaves are emerging. This is when the tree is easiest to overlook — it doesn't announce itself with flowers the way cherry or apple does. The new leaves are a fresh, bright yellow-green, and the surface has a slightly wrinkled texture in the youngest leaves that smooths as they expand.

The variable leaf shape — some leaves lobed, some not, on the same tree — is actually a useful identification feature once you know to look for it. The combination of variable leaf shape, toothed margins, alternate arrangement, and slightly rough leaf surface makes 뽕나무 fairly recognizable once you've seen it a few times.

In rural Korea, older mulberry trees are common along field edges and roadsides — remnants of former orchards or self-seeded from bird-dispersed fruit. In cities, they appear in parks and as street trees. By midsummer, the fruit makes their location obvious to anyone paying attention to the ground.

 ⚠️ Disclaimer

This blog documents Korean plants and their traditional uses for educational and cultural purposes only. Nothing here is medical advice. Unripe mulberry fruit and the milky sap from cut stems can cause digestive upset in some people; ripe fruit is generally safe. If you're considering using any plant medicinally, consult a qualified healthcare provider first.

*Photographed in Korea, April 2026. All field photography by The Korean Herbalist.*

**Tags:** 뽕나무, Morus alba, white mulberry, 오디, Korean mulberry, silk road Korea, Korean traditional medicine, 상엽, sericulture Korea, Korean spring trees