It seems an improbable notion of landscape architecture: Create a big pond to control the tide, surround it with 1,700 Japanese flowering cherry trees, and place near it a Roman monument to a president who never saw a Japanese cherry and didn’t care that much for Washington. And yet the Tidal Basin works as a beloved civic space, a two-mile promenade that calls us back year after year at blossom time.

Perhaps it’s the openness of the Tidal Basin, or the reflective quality of water, or the absence of skyscrapers, but the grand scale doesn’t overwhelm the abiding sense of serenity. What is it about a fleeting bower of creamy Yoshino blossoms that affects us so?

To me, it’s the poetic form of the tree and the subtle beauty of the delicate blossoms. The petals are white but seem the softest pink in some light, they are single in form, and at times are mildly fragrant and alivewith honeybees. They are at once fragile and as unstoppable as the sunrise.

(Click here to make your own cherry blossom origami.)

I asked Joe Krakora, the most Zen gardener I know, what he sees in them. He and his late wife, Polly, would go down to the Tidal Basin from their Georgetown rowhouse to savor blossom time at dawn. Krakora says he feels in a flowering cherry a force outside its physicality, “a space beyond the space” that invites reflection and spirituality. “It’s a Zen experience without knowing it’s a Zen experience,” he said.

Indeed, our whole relationship with Japanese plants is an unwitting Zen experience: Forget the flowering cherries for a moment — our landscapes, our lives are imbued with hundreds of garden plants from the Land of the Rising Sun.

The most striking example is the azalea, the blingiest bush in town, but others abound. Peruse your garden and what do you see? Chances are there’s a massing of the evergreen aucuba next to a camellia in full crimson bloom. Soon the lemon-yellow blossoms of the winter hazel will appear above the small white blooms of the ground cover pachysandra, while the pieris shrub will produce gorgeous red leaves along with cascading clusters of bell-like flowers.

Japanese plants have become integral to some of our most iconic American landscapes, not just at the Tidal Basin but at the White House, with its stunning Japanese maples and fall chrysanthemum displays, and at the U.S. Capitol and Library of Congress, where star magnolias offer the first bright flowering of March.

We may not realize it, but “an American garden without Japanese plants would be unrecognizable,” said Todd Forrest, vice president of horticulture at the New York Botanical Garden.

Most of our azaleas and many of our lilies came from Japan, along with the lacecap and mophead hydrangeas of summer. In April, the Japanese wisteria blooms along with crab apples bred with Japanese species, and in May, the rugosa rose opens with its intoxicating fragrance. This is the salt-tolerant shrub rose of the seashore.

From Japan came common evergreens, the boxwood-lookalike Japanese holly, the elegant and towering Japanese cedar, the Japanese yew and the Hinoki and Sawara false cypresses.

There are so many varieties of Japanese maple that whole nurseries are devoted to them. Gardeners turn to such Japanese beauties as the snowbell, the kousa dogwood, the umbrella pine and the stewartia. The ginkgo tree, thought of as Chinese, made its way first from Japan.

What would our gardens look like without Japan? Perhaps something like the cottage garden of Emily Dickinson in Amherst, Mass., where old-fashioned flowers were grown earnestly within a limited palette and in reticent display. She grew foxglove and lily of the valley, and would have known lilacs, hollyhocks and heliotropes, as well as varieties of daffodil and day lily. She might have known the blowzy peony — iconic to both the Chinese and Japanese — but she wasn’t a fan of something so beyond the bounds of New England modesty.

For the reclusive Dickinson, her garden became not just her muse but a conduit to the cosmos. To our modern eyes, it would seem pretty empty.

When I came to Washington years ago, I made the predictable mistake of trying to replicate the English gardens of my youth. The heathers turned brown in the heat, the wrong roses dropped their sickly leaves, the garden phlox grew white with mildew.

I noticed in friends’ gardens that their plants of Japanese origin seemed not only much happier but, in a way I didn’t understand at the time, much more at home.

As Washington celebrates the centennial of the cherry trees this spring — a gift of friendship from Tokyo Mayor Yukio Ozaki and first planted on March 27, 1912 — it’s worth asking, how did so many Japanese plants find their way into our gardens?

***

Anyone in search of the origins of Japanese plants in Western gardens soon comes to this conclusion: The floral floodgates opened relatively recently, as these things go.

Colonial Americans cultivated Old World plants such as apples, boxwood and parsley, as well as venerable New World beauties including Southern magnolias, bald cypresses and flowering dogwoods.

Until the 1850s, the rest of the world knew little about the flora of Japan, though its horticultural practices were advanced, and 18th-century residents of Tokyo, then known as Edo, and Kyoto would have known the glory of avenues of flowering cherry trees. Garden historian Christopher Thacker wrote that the Japanese garden was already “infinitely sophisticated while we in the west were still in bearskins.”

Japan had closed itself in reaction to Portuguese Christian missionaries who arrived in the 16th century. In the 1630s, the Japanese built a tiny island off the port of Nagasaki, named it Deshima and corralled the Portuguese there, before banishing them altogether.

The Japanese rulers allowed Dutch traders, who wanted Japanese goods, not souls. Deshima was the perfect place to contain them under guard. Only two Dutch ships a year were permitted to arrive.

For more than two centuries, successive members of the Dutch East India Co. provided the rest of the world with any knowledge of Japanese society, natural history and culture. Three of the company’s physician-naturalists became pivotal in introducing the West to Japanese flora.

In the 1690s, Engelbert Kaempfer, a German, planted a garden on Deshima and later wrote an account of Japanese life. Carl Thunberg, Swedish but convincingly Dutch to his wary hosts, arrived in 1775 for a 14-month stay and gathered plant specimens. He noted the astonishing fall coloration of a mind-boggling array of Japanese maples.

“Generations of Japanese horticulturists had cultivated and selected the extremes of variation displayed by these trees for garden and home ornament,” wrote Stephen A. Spongberg in his 1990 book “A Reunion of Trees.”

He noted that Thunberg was also smitten by magnolias, roses, lilies and honeysuckle. Thunberg sent dried, pressed plants back to botanists in Holland, but gardeners interested in growing these beauties had to wait a century to get their hands on them.

It was the third physician who did the most to unlock Japanese floral secrets. Philipp Franz von Sieboldarrived in 1823, though he was nearly turned back after a Japanese inspector detected his German accent. He convinced the inspector that his dialect was from the mountainous region of the Netherlands (a nation that rises to a lofty 1,056 feet).

He stayed in Japan for six years and on his return published books that established him as the leading Western authority on Japan.

Siebold was allowed to work in Nagasaki, off the island, and through Japanese friends received plants from wide and far. He gave us the mophead hydrangea and named it for his Japanese wife, Taki. He traveled to Tokyo to ceremoniously pay Deshima’s rent to the shogun. Along the way, he observed the wild and cultivated plants. Every little house had a sacred garden, some ornamented with bonsai.

“These dwarf trees are reared in flower-pots ...” he wrote, “and when they bear luxuriant branches upon a distorted stem, the very acme of perfection is attained.”

He also observed the delight with which Japanese gardeners grew excessively large vegetables, including a radish weighing 50 pounds.

Siebold’s adventure sounds like a plot from an opera. When his tour was over, he sailed away (not allowed to take his Japanese wife and daughter with him), but a gale blew his ship back. Porters found contraband in Siebold’s luggage, notably a map of Japan, considered a state secret. He was imprisoned for a year, then banished.

Back in the Netherlands, in Leiden, he established a Japanese garden and wrote books detailing every aspect of Japanese life. He had brought back 2,000 woodblock prints depicting the exotic, hidden civilization.

Of Siebold’s eight books, none was more important to botany than “Flora Japonica,” a lavish two-volume work first published in 1835. It contains descriptions and hand-colored lithographic plates of 150 Japanese plants, the final 22 not issued until 1870, four years after Siebold’s death.

The book gave botanists the first full measure of the trove of the Japanese garden at a time when Western interest in this inscrutable land was reaching a peak. It also unlocked the mystery surrounding the uncanny similarity between plants in Japan and the eastern United States.

Rare as the book is, I simply had to track down a copy and see it with my own eyes.

***

I made an appointment at the rare-book library at Dumbarton Oaks, Harvard’s international center for scholarship in Georgetown. Librarian Linda Lott led me to the reading room, a Classical revival annex to the Federal mansion.

Although the library’s “Flora Japonica” is a copy, a facsimile from the 1970s, it is precious and must be treated with the same respect as the original. Lott laid out before me a pair of white cotton gloves, ribbons to mark pages and a large felt wedge on which to rest the opened volumes.

In the stillness and finery of the library, examining the volumes in itself became like some sacred Japanese ceremony.

Even in the stylized flat fashion of the botanicals, the plants leap from the page with an eerie familiarity. There is the leatherleaf rhododendron, with its fabulous trusses of rose-colored flowers; the spike winter hazel, one of the first shrubs to flower in spring; and, of course, the flowering cherry.

Gingerly turning the thick pages, I came across two lithographs I found particularly moving. One was of the camellia, presented in a deep carmine red in various stages of bud and flower. The image lost none of its poetry in its scientific value. The other was a big, sky-blue mophead hydrangea, the Hydrangea Otaksa (now called Hydrangea macrophylla).

Who knew that this common plant of Atlantic beach homes commemorates the love of a young, lost wife? Siebold returned to Japan in 1859, and saw Taki once more, briefly. They had both remarried. One can only imagine the thoughts that went through his mind. It was clear that though he had left Japan years before, the country never really left him. His last words, reportedly, were, “I am going to a beautiful, peaceful country.”

When “Flora Japonica” appeared, those lucky enough to have seen it may have thought Siebold exaggerated the beauty of the plants, but a young American botanist named Asa Gray saw something else.

***

Gray sailed to Europe in 1838, when he was 28, to meet some of the great botanists of his day. In Munich, he met Siebold’s co-author, J.G. Zuccarini, who gave Gray a copy of “Flora Japonica” as a gift. Gray, who spent his career at Harvard, saw the strange kinship between many Japanese species and those native to the eastern United States.

He developed a view that tallied with the evolutionary theories of Charles Darwin. The two corresponded, and Darwin told him of his theory of natural selection a year before releasing “On the Origin of Species” in 1859. In the same year, Gray published his own theory that plants from Japan and the eastern United States share a common ancestry.

One obvious example was Virginia creeper, an American native, and Boston ivy, from Japan. There were obvious parallels, too, between Japanese and American pachysandra, rhododendron, viburnum and stewartia, to name a few. Gray concluded that the glaciers of the Pleistocene period cleaved such species, and they evolved separately afterward.

“Gray’s work showed that Darwin was right about the transmutation of species,” wrote A. Hunter Dupree,author of “Asa Gray: American Botanist, Friend of Darwin.”

This was all very interesting botanical brainstorming, but to get long-lost Japanese plants into our gardens, something else had to happen.

Enter Commodore Matthew Perry and the U.S. Navy. Or, more precisely, enter Commodore Perry entering Edo Bay with four vessels, two of them coal-fired steamers that appeared as menacing dragons. The conversation went something like this: “Enough of this isolation nonsense.” Perry returned eight months later and negotiated a treaty.

Almost immediately, plant collectors arrived from America and Europe to capitalize on the pent-up demand for the Japanese plants.

In the 1860s, an American living in Yokohama, George Hall, sent back seeds and plants of ornamentals, including Japanese maples, yew and false cypress. Others brought back Boston ivy, Japanese hemlock and dogwood. A Scots American named Thomas Hogg returned with stewartias, snowbells and katsura.

Within 30 years, the floodgates of Japanese flora were fully open. Japan, now in its Meiji Restoration, repudiated its feudal past, embraced Western science and technology, and created an industrialized society.

The Meiji government invited hundreds of foreign specialists “to teach production and marketing procedures,” as well as to establish their own Japanese-based nurseries, according to Thomas Elias, an expert on Japanese horticulture and former director of the National Arboretum.

Elias wrote in a scientific paper published in 2005 that four Japanese nurserymen established the Yokohama Nursery Co., in 1890, which became a leading exporter of Japanese plants, seeds and bulbs to the United States.

***

I ventured to the Special Collections room at the National Agricultural Library, a lonely-looking high-rise where the Capital Beltway glances Route 1 in Beltsville.

Donning another pair of white gloves, I carefully removed the documents from their protective brown envelopes. The contents are still mouth-watering for any green-thumbed gardener. At the time, they must have seemed a treasure chest of novel ornamental plants. Japanese apricot, magnolias, Japanese irises, witch hazel, cycads, bamboos and grasses, Japanese cedars, the list goes on and on.

F. Takaghi, owner of Tokio Nurseries, “begs to assure the public that his stock is genuine as marked and first class in every respect.” It took 30 days to get the plants from Yokohama to the Atlantic seaboard, via ship and rail.

Yokohama Nursery’s 1898 catalogue ran to 73 pages and included 77 varieties of woody and herbaceous peonies, 34 varieties of camellia and 24 varieties of azalea.

The 1902 catalogue, bound in red silk, featured an illustration of a Japanese cherry and is a thing of beauty in itself. It had grown to 80 pages, and its offerings included 124 varieties of chrysanthemum and 40 species and varieties of lilies. Lilies, showy, scented and providing valuable blooms in the heat of summer, had become wildly popular; by the end of the 19th century, the value of lily exports was three times that of all other plants, according to Elias.

Yokohama’s 1903 catalogue included a sweet and prescient if ungrammatical reference to the newly offered Yoshino cherry: “No park without this tree seems not perfect.”

This was a view shared by David Fairchild, an esteemed plant explorer for the U.S. Department of Agriculture who was in Japan the previous year and was struck by the beauty of the trees. He shipped about 30 varieties home for the department and in 1905 ordered 100 trees for his estate in Chevy Chase.

Their fame spread, and first lady Helen Taft was convinced they were the plant to use in her plan to beautify Potomac Park. The first gift of trees from Japan, some 2,000, arrived in 1910, but they were sickly and bug-infested and had to be burned. A healthier batch of 3,020 arrived in spring 1912. (The spread of Japanese flora has not been without its problems, particularly with plants that became invasive: among them, Japanese honeysuckle, the paulownia tree and kudzu.)

In 1914 and 1915, Ernest Wilson brought back more flowering cherry trees, conifers and 50 varieties of Kurume azaleas that would transform the American garden.

Collectors returned to Japan after World War II. On the remote southern island of Yakushima, John Creech, collecting jointly for the National Arboretum and Longwood Gardens in Kennett Square, Pa., found a species of crape myrtle named Lagerstroemia fauriei. This small tree had beautiful plant architecture, striking cinnamon bark and a resistance to powdery mildew. Hybridizer Donald Egolf used it to create a series of varieties in widespread use. The most common, almost to the point of ubiquity, is the Natchez cultivar.

I called the late Egolf’s successor at the federal Agricultural Research Service, Margaret Pooler, and asked her to show me what Japanese plants she was using in her breeding programs. At the National Arboretum in Northeast Washington, she led me into an unheated greenhouse where cherry trees had been coaxed into early bloom. Growing in large pots, their branches were covered in large, bell-like blossoms of the deepest magenta.

Since the current cherry breeding program began in the 1980s, she has introduced two varieties and is about to release a third. All three are the cherry tree versions of “American Idol” winners: Hundreds of competitors have been dropped along the way. It can take 20 years between making a cross and introducing a plant to the nursery trade.

What is Pooler looking for? Cherry trees that are disease-resistant, happy in poor soil, novel in size and flower color, and easy for nurseries to grow.

Around the Tidal Basin, Joe Krakora and I see perfection. Pooler sees possibilities. She has 20 cherry species and 400 hybrids growing at the arboretum, all ready to lend their genes to breeding programs that will continue for decades to come. Such is the bounty of Japan.

“I’m building on the work of Don Egolf, and people are going to be building on the work I did,” she said.

If Asa Gray were to return today, he would see in virtually every garden a reunion of his plants long separated but now together again, generating that joyful space beyond the space.

“We have Chinese plants and European plants,” said Forrest, of the New York Botanical Garden, “but if you subtracted any geographic source, none would be so missed by American gardeners as Japanese plants.”

Adrian Higgins is a Washington Post staff writer. To comment on this story, send an e-mail to wpletters@washpost.com.