Tade: The Bitter Weed Behind a Japanese Proverb, and Its Tall Cousin in the Autumn Garden
In Japan there is a saying, tade kuu mushi mo sukizuki. Word for word, it means "even the bug that eats tade has its own taste". In English you might say there is no accounting for taste.
Tade is the Japanese name for a group of plants in the knotweed family, the genus Persicaria. Most people in Japan know the proverb, but far fewer could point to the plant itself.
We are a small tree care and landscape business in Mie Prefecture, central Japan. In autumn we often find one of these plants, a tall pink tade, growing at the edge of the gardens we look after. This page is about the plant from the proverb, and the cousin that people grow for its flowers.
The tade in the proverb is a hot plant
The tade in the saying is yanagitade, Persicaria hydropiper. In English it is called water pepper. Its scientific name says the same thing: hydro for water, because it grows by streams and wet ground, and piper for pepper.
Chew a leaf and it is sharply hot. The Yamashina plant collection of the Japanese drug company Nippon Shinyaku says visitors who try it are always surprised by how strong it is. The heat comes from a compound called polygodial, which is known to discourage insects from eating the plant.
And yet some insects eat it anyway. The collection notes that its own water pepper plants often show bite marks. That is the joke inside the proverb: a leaf so hot that most creatures avoid it still has its fans. People are the same. What one person dislikes, another person loves.
Tade on the Japanese table
Water pepper is not only a weed. In Japan it has long been used as a herb.
The best known use is tadezu, tade vinegar. The leaves are ground and mixed with vinegar to make a bright green sauce served with salt-grilled ayu, a river fish of summer. Tiny sprouts, called metade, are laid beside sashimi as a garnish. There are also red-purple leaf types grown for this, called beni-tade.
So the bitter plant of the proverb is also a small, familiar flavour of Japanese food.
The tall cousin: ookedate
The plant in our photo is a different tade. Its standard Japanese name is ookedate, Persicaria orientalis. It is also called oobenitade, a name used for the type grown in Japan, which has long, deep pink flower spikes that hang down.
It is an annual that can grow one to two metres tall in a single season, with large, hairy leaves. It flowers from summer into autumn. In our area of Mie we still see it in flower around the edges of fields and gardens as autumn arrives.
It is not native to Japan. It is found widely across Asia, from China and Korea to India and Southeast Asia, and as far as Australia. It is thought to have come to Japan in the Edo period as a medicinal plant. An illustration in Kinmo Zui, a Japanese picture encyclopedia published in 1666, is believed to show this plant. The Tokyo Herbal Medicine Association notes that Edo-period herbal books describe using it for boils.
Because its flowers are so bright, it came to be grown for ornament across Japan, and it now also grows wild in vacant land and along field edges where seeds have escaped.
The same plant in American gardens
Readers in North America may know this plant already. In old-fashioned American gardens it is called kiss-me-over-the-garden-gate, a name that suits a plant tall enough to lean over a fence. Monticello, Thomas Jefferson's home in Virginia, includes it in its plant encyclopedia under another old name, Prince's Feather.
The same tall pink plant that Japanese gardeners know as oobenitade has its own long history on the other side of the Pacific.
Another tade that coloured Japan blue
One more member of the family is worth knowing. Tade-ai, Persicaria tinctoria, is the plant behind traditional Japanese indigo.
In Tokushima Prefecture on Shikoku, the dried leaves are fermented to make sukumo, a natural indigo dye. Tokushima's indigo, called Awa-ai, spread to markets across Japan in the Edo period. According to Tokushima Prefecture, it still makes up most of Japan's production and supports the colour known around the world as Japan Blue.
A hot herb, a garden flower and a blue dye all come from the same group of plants.
If it grows in your garden
Ookedate is an annual, so each plant lives for one season. It comes back from the seeds it drops.
If you do not want it to spread, pull it out before the flowers set seed. If you enjoy it, leave a few plants. Just remember that dropped seeds will bring more plants the next year, and that a plant two metres tall can shade out smaller plants around it.
The flower spikes also dry well. Cut them a little before they are fully open, then hang them upside down in a shaded, airy place. The colour fades somewhat, but the spikes keep their shape.
Common questions
Is the tade in the proverb the same as the pink garden plant? No. The proverb refers to water pepper, a smaller plant with hot leaves. The tall pink plant is ookedate, a cousin in the same genus.
Is ookedate native to Japan? No. It is native to other parts of Asia and is thought to have arrived in the Edo period, first as a medicinal plant.
Can I eat ookedate leaves like water pepper? We do not recommend it. Water pepper and its sprouts are the tade used in Japanese food. Ookedate is grown for its flowers.
A plant that tells you about taste
The proverb says that tastes differ. The tade family itself proves it: one plant is valued for its heat, one for its flowers, and one for its blue.
Next time you see a tall pink spike leaning over a fence in autumn, you will know it is a cousin of the plant from one of Japan's most familiar sayings.
