Over one hundred years ago, Professor Asa Gray of Harvard University, in a series of papers, expounded an interesting aspect of plant distribution: the distinct relationships existing between the floras of eastern North America and eastern Asia, particularly China and Japan.
Many genera of plants, such as Magnolia, Liriodendron, Hamamelis, Wisteria, Pachysandra, Chionanthus, and Catalpa, to mention only a few, are found only in these two distant regions and nowhere else in the world.
Various geological and paleogeographic factors, especially the effects of the last glaciation, brought about this unique relationship among plants.
Because of this basic relationship of the vegetation and similarities in climate and other physical conditions, most plants of eastern Asia thrive in eastern North America. The flora of eastern Asia is also the richest in temperate regions.
Due to continuous botanical exploration and introduction in the last two hundred years, we have today more species of Asiatic origin growing in American gardens than from any other region.
The preponderance of Asiatic plants in American gardens can be best illustrated by the frequent occurrence of the name “japonica” among garden plants, such as Cryptomeria japonica, Wisteria japonica, Lonicera japonica, et cetera.
The last named plant is the ubiquitous and frequently troublesome Japanese honeysuckle.
Western Botanists’ Influence
Many plants, however, bearing the name japonica, are not native to Japan but were introduced from the mainland in former times; for example, Anemone japonica, Camellia japonica, and Sophora japonica.
These, along with many others like the tree peony, herbaceous peony, garden chrysanthemum, Japanese apricot, and other familiar garden plants, were brought from China to Japan centuries ago and have long been firmly established in Japanese gardens.
When Western botanists like Kaempfer, Thunberg, and Siebold first studied the Japanese flora in the 17th century, they believed all these plants to be native to Japan and hence bestowed the name japonica on many of them.
Most of these plants were introduced into European gardens by early traders. Thus, when the American colonists began to plant their gardens in the New World, a large number of familiar garden plants from China and Japan were already available to them.
During the 17th and 18th centuries, plants like chrysanthemum, hollyhock, cockscomb, peony, day-lily, camellia, crape-myrtle, honeysuckle, azalea, and many others of Asiatic origin were already popular garden plants in America.
Ginkgo Tree
The ginkgo tree, for example, now so familiar in American cities as a street tree, originated in China and was long cultivated in Japan. The first tree on record to bear fruit in America was the one in Germantown, Philadelphia, in the garden of John Wister, built in 1744.
The tree was reportedly received from Japan as a seedling, a gift from the Japanese Emperor to Wister, and is believed by some to be the earliest one in this country.
Japanese Flowering Cherry
Among the many garden plants of Japanese origin, perhaps the most popular and well-known is the Japanese flowering cherry, the national flower of Japan.
Many forms are now planted in the West; these vary from handsomely drooping forms (Prunus subhirtella pendula) to gorgeous double forms (Primus serrulata lannesiana).
The famous trees planted along the tidal basin of Washington are mostly Prunus yedoensis, the cherry most generally planted in Tokyo and elsewhere in Japan. Its flowering is the occasion of a popular festival.
Japanese Maple
The Japanese maple is among our garden’s most striking and showy small trees. This distinct contribution from Japan now graces nearly every American garden throughout the country, bringing brilliant coloration to the doorway in spring and autumn.
The maple is a favorite tree of the Japanese, and hundreds of named varieties are grown in their gardens. Perhaps no other tree under cultivation has as many forms as the Japanese maple.
Many beautiful forms of camellia originated in Japan, especially the sasanqua camellias
Azalea
Japan is the home country of many of the well-known forms of azaleas. Azaleas are extensively cultivated there, both as garden plants and as potted dwarf plants. By intensive selection and hybridization, many garden varieties are derived.
The many so-called Indian azaleas are all introduced from Chinese and Japanese gardens, raised there by hybridizing Rhododendron indicum and Rhododendron mucronatum, two Japanese species, with allied species.
Another important Japanese species is Rhododendron obtusum. A large number of named varieties, varying in shade from white to deep red, are grown in Japanese gardens, including the well-known Kurume azaleas.
Japanese Irises
The Japanese irises, belonging to a single species, Iris laevigata, form a distinct group of garden irises.
Irises are among the most beloved plants in Japan, and they appear frequently as a decorative motif on their exquisite lacquer, chinaware, and other objects.
In Japan, there are numerous named varieties of Japanese irises, perhaps even more than in the “German” iris group of European origin.
These highly ornamental plants, with their distinct slender leaves and large flowers, have become favorite garden subjects all over the temperate world.
Japanese Plants
These are only some of the more widely known plants of Japanese origin. In the American garden, numerous other species of Japanese origin are in common cultivation.
Among the trees, there are the:
- Familiar umbrella pine
- Japanese red pine
- Japanese black pine
- Cryptomeria
- Hinoki cypress
- Sawara cypress
- Japanese magnolia
- Katsura-tree
- Kakri persimmon
- Zelkova
- Paulownia
Among the shrubs are such common ornamentals as:
- Japanese yew
- Japanese quince
- Japanese spirea
- Kerria
- Rhodotypos
- Japanese oleaster
- Japanese witch-hazel
- Japanese holly
- Japanese spindle-tree
- Fatsia
- Aucuba
- Ardisia
- Callicarpa
- Pieris
- Enkianthus
- Styrax
- Japanese dogwood
- Japanese snowball
- Weigela
Japan contributed such vines as Japanese wisteria and Japanese honeysuckle and such ground cover plants as pachysandra.
Herbaceous plants of Japanese origin include Japanese lilies, daylilies, lilies, and various species of lycoris. The common Easter lily came originally from the Ryukyu Islands.
Popularity of Japanese Plants
The popularity of Japanese plants in American gardens is mainly due to the many choice garden forms developed in that country.
With great patience and perseverance, Japanese gardeners and plantsmen have developed many desirable horticultural forms over the centuries from species originating in their own country and other parts of Asia.
The so-called Japanese morning glory can best illustrate their dexterity. This plant was first introduced to the American trade from Japan in 1895.
There are many forms, sometimes very curious oddities, with various variations in flowers and foliage.
The Japanese took a great fancy to this plant, “Asagao,” the culture of which amounted to a popular craze in about 1830. This plant is still very popular in Japan, and seeds produced in Japan are sold in many countries.
Yet this plant, Ipomoea hederacea, is not native to Japan but to tropical America and the warmer parts of North America.
The Japanese morning glories are only selected and improved strains produced by oriental ingenuity out of this occidental species.
44659 by Hui-Lin Li