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Plant Exploration in Japan

By Peter Zale, Ph.D., on July 14, 2016
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A view of Mt. Fuji at dusk from the home of our guide, Mr. Shigeharu Matsuda, in Yamanashi, Japan.A view of Mt. Fuji at dusk from the home of our guide, Mr. Shigeharu Matsuda, in Yamanashi, Japan.

Plant hunting often conjures images of remote, steamy jungles rich in exotic species new to gardens and science. While scientists from Longwood Gardens often participate in such expeditions to discover plants for our displays, the truth is that plant hunting and exploration can take on myriad forms. One of the most efficient ways of obtaining new and useful plants is to visit nurseries across the globe. Since many countries have well-established nursery industries, this type of plant exploration can be particularly useful for investigating the latest plant introductions from around the world.

As Curator and Plant Breeder at Longwood Gardens, I am currently exploring nurseries throughout Japan with Andrew Bunting, Assistant Director of Gardens and Director of Plant Collections at the Chicago Botanic Garden. With the help of our guide, Mr. Shigeharu Matsuda, we hope to introduce new plants that will enhance the displays at both gardens.

Peter and Andrew study the flowers of Cornus ‘Mountain Moon’ with Mr. Akira Shibamichi, owner of the world-famous Shibamichi Honten Nursery. Peter and Andrew study the flowers of Cornus ‘Mountain Moon’ with Mr. Akira Shibamichi, owner of the world-famous Shibamichi Honten Nursery.

Japan has a long horticultural history that has resulted in an appreciation for many kinds of plants and a constant supply of new germplasm (plant genetic resources). The diversity of climate and topography in Japan has produced a range of plant selections that can be used in all areas of the garden, from outdoor displays to conservatory plantings. Many Japanese plants are well-adapted to garden conditions in the eastern US, as the climate is similar, with hot humid summers and cool or cold winters. The goal of our trip was to visit and build relationships with some of Japan’s most famous nurseries, and bring home some of the newest and most beautiful plants being grown there.

One of our first visits was to the world-famous Shibamichi Honten Nursery, which is unsurpassed for specialty woody plants in Japan. Owner Akira Shibamichi, well-known to many US horticulturists for his numerous woody plant introductions, gave us a wonderful tour of his entire production and retail nurseries. He also showed us a property that he donated to the city of Angyo, which will be transformed into a public garden showcasing his many woody plant introductions.

Mr. Shibamichi showing us the property he donated to become a public garden to showcase his plant introductions. Mr. Shibamichi showing us the property he donated to become a public garden to showcase his plant introductions.

A particularly lovely pink variegated selection of Saxifraga cortusifolia. A particularly lovely pink variegated selection of Saxifraga cortusifolia.

It would be impossible to recount every detail of every nursery we’ve been to (enough to fill a book!), but I’d like to outline some of the trends we’ve seen. One of the strongest impressions is the overwhelming number of variegated plants—Japanese horticulturists have discovered a variegated version of basically every species native to Japan. If it hasn’t yet been found, it won’t be long before it is! The degree of variegated forms even within a single species can be staggering, including leaves with white or cream-colored margins, yellow leaves, leaves spattered with white specks, leaves streaked in myriad colors, leaves showing more than one kind of variegation … and the list goes on!

A variegated form of the handkerchief tree (Davidia involucrata). Variegated plants are particularly popular in Japan and have been selected at nurseries throughout the country. A variegated form of the handkerchief tree (Davidia involucrata). Variegated plants are particularly popular in Japan and have been selected at nurseries throughout the country.

A variegated winter-hazel (Corylopsis spicata) that caught our eye. Winter-hazels grow particularly well in the mid-Atlantic region and this will be a nice complement to the large collection at Longwood. A variegated winter-hazel (Corylopsis spicata) that caught our eye. Winter-hazels grow particularly well in the mid-Atlantic region and this will be a nice complement to the large collection at Longwood.

The umbrella plants (Syneilesis aconitifolia and S. palmata) are becoming more popular in American horticulture. They are easy-to-grow plants with a showy foliage and interesting late-season flowers. The number of variegated and different foliage forms is staggering. The form shown here is S. palmata ‘Ohgan-ba’, which means gold leaf. The umbrella plants (Syneilesis aconitifolia and S. palmata) are becoming more popular in American horticulture. They are easy-to-grow plants with a showy foliage and interesting late-season flowers. The number of variegated and different foliage forms is staggering. The form shown here is S. palmata ‘Ohgan-ba’, which means gold leaf.

And finally, a pink and white variegated form of the beautyberry (Callicarpa japonica). And finally, a pink and white variegated form of the beautyberry (Callicarpa japonica).

Driving around Japan at this time of year, some of the most obvious flowering plants are various hydrangeas. Popular in Japan, they’re planted in gardens, along roadsides, and almost anywhere that can accommodate them. Pictured here are a few of the many selections we have seen growing throughout the country. Most of them are selections of Hydrangea macrophylla and Hydrangea serrata, the latter being a reliably flowering species in southeastern Pennsylvania.

Hydrangea spp. Hydrangea spp.

We are also visiting botanical gardens to gain a broad perspective of horticulture in Japan, and to network on behalf of our respective gardens. The botanical gardens exhibit the same range of variation as the plants they have selected. We have experienced the traditional gardens that most people associate with Japan: elegantly pruned and sculpted pines, bamboo, perfectly trimmed azalea hedges that call to mind the boxwood hedges of Europe and Longwood Gardens, and perfectly placed pagodas and lanterns that complete the look and provide a unique sense of place. Other gardens bridge the gap between traditional Japanese gardens and the modern trend toward naturalistic gardens. At the Yukiguni Botanical Gardens there is a strong emphasis on Japanese native plants used in large numbers in a semi-cultivated, highly naturalistic setting. One of the most important garden visits was with Mr. Kodai Nakazawa, chrysanthemum specialist at the Shinjuku Gyoen National Garden in Tokyo. Since our Chrysanthemum Festival is such an important part of Longwood’s Conservatory displays, we visited to gain insight into his techniques.

Mr. Kodai Nakazawa, chrysanthemum specialist at Shinjuku Gyoen. Mr. Kodai Nakazawa, chrysanthemum specialist at Shinjuku Gyoen.

Chrysanthemums being grown for display in November. Unlike Longwood, all of these chrysanthemums will be displayed outside. The mild climate in Tokyo allows for the outdoor displays. Chrysanthemums being grown for display in November. Unlike Longwood, all of these chrysanthemums will be displayed outside. The mild climate in Tokyo allows for the outdoor displays.

The thousand bloom chrysanthemum is one of the highlights of the Chrysanthemum Festival at Longwood, and the same is true at Shinjuku Gyoen. Pictured here is one of the thousand bloom mums in production. The plants are produced in slightly different ways than those at Longwood, but the result is the same. The thousand bloom chrysanthemum is one of the highlights of the Chrysanthemum Festival at Longwood, and the same is true at Shinjuku Gyoen. Pictured here is one of the thousand bloom mums in production. The plants are produced in slightly different ways than those at Longwood, but the result is the same.

Shinjuku Gyoen is also actively breeding chrysanthemums. Each year they plant 2,000 seedlings, of which only a few plants are selected for further breeding and production. Shinjuku Gyoen is also actively breeding chrysanthemums. Each year they plant 2,000 seedlings, of which only a few plants are selected for further breeding and production.

This is a just a taste of everything we’ve seen. The total content of our trip would fill dozens of blog posts. And this is just the first of two plant exploration trips this year. In August and September, I’ll be traveling to the Republic of Georgia to participate in field collection to introduce new species to Longwood. I’m looking forward to sharing this expedition with our blog readers in September!

Photos by Peter Zale.

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