WASHINGTON — At the Japanese Embassy's Japan Information and Culture Center, a recent slide lecture on gardening began with Yotaro Ono stepping on stage in samurai regalia. He pulled out the feudal warrior's best friend, a curved sword, and began slashing the air with it.

Ono then staged a series of kata, mock fights with his opponent, a martial artist from Idaho named Anthony Abry. The cries were alarming but, thankfully, Ono had switched to a wooden sword.

I was spellbound, not just by the unexpected display, but by the fact that three days earlier I had met Ono in his blazer and slacks at the National Geographic Society. In the Explorer's Hall museum on M Street NW, the 63-year-old landscape architect from Kyoto has created his vision of a warrior's garden, on display through April 29.

Ono is designer and martial artist. In an interview he spoke of the linkage between art and war and the fact that great samurai such as Miyamoto Musashi applied the same mental rigors to garden-making, writing haiku and painting as to dispatching a foe.

It occurred to me that Ono could combine his talents in other ways: He could cut a swath through America, taking out all the tacky, misbegotten "Japanese" gardens that afflict the landscape. You know what I mean: The scattered, neglected gravel that needs a raking, a weeding and a way to exclude the cat. The puny stone lantern fashioned from a concrete mold and tipping to one side. Or the sad little arched bridge planted between isolated garden beds.

Please understand, I'm a huge fan of successful Japanese-style gardens in the West. They can, when well done, create a space where plants and structure come together to form a composition artistic and serene. This is surely the ideal of any garden. But to achieve that you have to start with design integrity and reject the idea that a Japanese garden can be evoked when characteristic elements are used merely and excessively as props.

At heart, said Ono, the garden is a vehicle for creating a feeling. "For example, if you were born by the sea and you live in the city, remember what you felt" in childhood, he said. Or go for a walk in the country and observe, carefully, how nature arranges trees or the placement of rocks, or pebbles in a stream. Then synthesize that in the garden but in a simplified, even abstract way, he said.

One of the most common mistakes, he said, is in thinking that every space must be planted or decorated. He moves to a copy of a famous painting by Musashi, of a shrike perched on a branch. The bird is surrounded by air. It is only through considering void that we comprehend mass.