Why Is Kudzu So Hard to See in Seoul?

 Leave Seoul on a summer highway, and the landscape can suddenly become strangely green.

As the city disappears behind you, hillsides begin to look as though someone has thrown a giant green blanket over them. Trees seem to vanish beneath layers of leaves. Roadside slopes become thick walls of green. Sometimes the sight is so complete that it almost looks artificial.

And one of the main characters behind this spectacular summer landscape is kudzu, or 칡 (chik).

In Korea, kudzu is an extremely familiar plant. It is a climbing vine that grows widely in the countryside and mountainous areas. Its stems can climb over other plants and trees, while its enormous leaves spread outward to capture sunlight. In Korea, it is common enough to be part of the landscape rather than something people stop to identify. The plant can grow many meters long, and its purple-red flowers appear in August.

But this raises an interesting question:

If kudzu can cover entire hillsides outside Seoul, why don't we see it covering the city?

The answer is not that Seoul has no kudzu.

Kudzu can be found in Seoul's urban forests as well. But the conditions that allow it to create those enormous green carpets are much more common outside the dense urban core.

Kudzu loves sunlight and open space. It is especially successful along roadsides, forest edges, abandoned fields, and other disturbed areas. When it finds a suitable opening, it can spread rapidly and climb whatever stands in its way. In ideal conditions, its vines can grow as much as about 30 centimeters in a day.

Now think about what happens when you leave Seoul.

A highway cuts through hills and mountains. Roadsides open up the forest. Slopes receive plenty of sunlight. There are long stretches of land where vegetation is not being managed as carefully as it is in the middle of a city.

That is almost a perfect stage for kudzu.

Seoul, by contrast, is a highly managed urban landscape. Trees along streets and other public green spaces are maintained for safety, visibility, and the health of the urban environment. Forest-management agencies in Korea also regard climbing vines such as kudzu as a problem along roads and in forest areas because they can climb trees, block sunlight, and interfere with tree growth.

So the difference is not really Seoul versus no kudzu.

It is managed city versus open landscape.

There is also another reason kudzu is particularly interesting in Korea: it has a completely different cultural image from the one it has acquired in the United States.

Kudzu roots have long been used in Korea. The root, known as galgeun (갈근), has been used as food and in traditional practices, and kudzu is also associated with products such as kudzu tea and kudzu starch. Historical Korean records even list kudzu root among foods that could be used during times of famine.

In the United States, however, kudzu has become famous for a very different reason.

Introduced from Asia in the late nineteenth century, it was once promoted for purposes including erosion control and forage. It subsequently spread widely across the southeastern United States and became one of the country's best-known invasive vines. The U.S. Forest Service describes it as an invasive plant capable of forming dense blankets that overwhelm other vegetation and trees.

The same plant can therefore tell two very different stories.

In Korea, kudzu is something people may associate with mountains, summer greenery, traditional food, and an old familiarity with the countryside.

On a summer highway outside Seoul, however, it can look almost wild enough to swallow the landscape.

Perhaps that is why the next time you leave Seoul in August, it is worth looking beyond the traffic.

When the hills beside the highway turn into what looks like one enormous green carpet, take a closer look.

That carpet may not be the forest itself.

It may be 칡 (chik).