Siebold Hemlock, Tsuga sieboldii

January 29, 2019

No white nor red was ever seen

So am’rous as this lovely green

-Andrew Morrell

As leitmotif to last time’s “who does your garden grow,” we turn next to Siebold Hemlock, Tsuga sieboldii. The genus Tsuga is small with just nine to eleven species, depending on taxonomic analysis, compared with the much larger genus Pinus, or pines. All hemlocks are medium-sized to large, evergreen trees, native to North America and Asia. Previously we have reviewed Canadian hemlock, by far the most prevalent species growing at Mount Auburn.

Siebold Hemlock, Tsuga sieboldii, also referred to as Southern Japanese hemlock may reach heights of 100-feet in the wild, but more often half that tall in landscape use. They have single, flattened, needle-like leaves, each about ½-inch-long, with smooth edges and a tiny notch on the tip. The undersides have two white stomatal bands. The seed cones when ripe are pale brown, one-inch-long.

Native to the Japanese islands of Honshu, Shikoku, Kyushu and Yakushima, they grow at elevations of 1,300 to 5,200-feet, in a moist, maritime climate. Rarely growing in pure stands, they commonly grow in mixed conifer forests with Cryptomeria japonica, Chamaecyparis obtusa, Sciadopitys verticillata, Pinus parviflora, Pinus densiflora and Abies firma. The Gymnosperm Database cites a tree stump found on Yakushima Island with 794 annual growth rings. Other researchers have derived ring-counted ages of 685 years and 639 years on other individuals. Ran Levy-Yamamori and Gerard Taaffe in their Garden Plants of Japan state, “On the Kii peninsula [of Honshu] …this conifer has been designated as a national monument.”

Siebold Hemlock, Tsuga sieboldii was named to honor Phillip Franz von Siebold (1796-1866), German born physician who became one of the most famous names associated with Japanese plants grown in Europe and later in the United States. Wanting to explore exotic countries he went to Holland, successfully obtained a position of surgeon major in the Dutch East Indies Army, initially posted in Java in 1822. The following year he was sent to Japan. This was still during the Military Shogunate rule (1603-1868), also called the Edo Period, when Japan isolated itself from the outside world. Only the Dutch were then allowed to trade with Japan, a 200-year monopoly, through Deshima Island, an artificial island in the bay of Nagasaki.

Working as physician for six years (1823-29) he introduced techniques and methods of western medicine and western scientific knowledge. Stephen Spongberg in his fascinating Reunion of Trees recounts, “…Through medicine and his skill as a surgeon, Siebold achieved fame and notoriety throughout Japan. He performed the first cataract operations witnessed by the Japanese, and his ability to restore sight to the near-blind increased his reputation and the reverence with which the Japanese came to regard him. Because he refused payments for his medical services and advice, the Japanese responded in their time-honored tradition of sending gifts in appreciation, and…his…collections of Japanese objects expanded.”

He founded a medical school and clinic, was allowed to marry a Japanese woman, Kusumoto Taki (1807-65), and permitted to move to the mainland above Nagasaki. There he created a botanical garden and arboretum. However, in 1829 he was expelled from Japan for the possession of Imperial maps of Japan and Korea (gifts) which was declared high treason for foreigners. He was forced to leave his wife and their daughter Kusumoto Ine (1827-1903) behind. Ine later became the first female physician of western medicine in Japan.

Returning to Leiden, Holland, he established a nursery specializing in Japanese flora, introducing over 730 plants, many still popular today including Malus floribunda, Sorbus alnifolia, Wisteria floribunda, Hydrangea paniculata ‘Grandiflora’, Hydrangea anomala subsp. petiolaris, Forsythia suspensa var. sieboldii and many others. In 1863 his nursery catalog listed 838 species and varieties. In 1858 his banishment from Japan was lifted and Siebold returned to Japan a second time from 1859-62.

In addition to live plants, he acquired 12,000 dried plant specimens of over 200 different species. Many of these herbarium specimens were classified in collaboration with Munich botanist Joseph G. Zuccarini (1797-1848) to author as Siebold & Zuccarini, Flora Japonica (1835-41).

Harvard University’s botanist Asa Gray (1810-1888) used Flora Japonica as he studied the close similarities of the floras of eastern Asia and eastern North America, which added to understanding of how different species arise. Gray’s disjunct species botanical work in turn was shared with Charles Darwin (1809-1882) to compliment his theory of species evolution, leading up to his 1859 publication of the Origin of Species.

I robbed the Woods-

The trusting Woods-

The unsuspecting Trees

Brought out Burrs and mosses

My fantasy to please-

I scanned their trinkets curious-

I grasped-I bore away-

What will the Oak tree say?

-Emily Dickinson

In addition to Siebold Hemlock, Tsuga sieboldii there is a long list of plants named to honor him:

Viburnum sieboldii, Siebold viburnum
Malus sieboldii, Siebold’s crabapple
Magnolia sieboldii, Oyama magnolia
Hosta sieboldii, Hosta
Forsythia suspensa ‘Sieboldii’, Weeping forsythia
Prunus sieboldii, Takasago cherry
Dryopteris sieboldii, Siebold’s wood fern
Berberis sieboldii, Barberry
Asarum sieboldii, Korean wild ginger
Primula sieboldii, Siebold’s primrose
Lychnis sieboldii, Siebold’s catchfly
Sedum sieboldii, October daphne stonecrop
Rubus sieboldii, Molucca raspberry
Stachys sieboldii, Crosne
Populus sieboldii, Japanese aspen
Calanthe sieboldii, Siebold’s calanthe orchid
Castanopsis sieboldii, Itajii chinkapin
Ostericum sieboldii, water dropwort

As well as:

Alnus sieboldiana, Japanese alder
Corylus sieboldiana, Japanese hazel
Euonymus sieboldiana, winged spindle tree
Euphorbia sieboldiana, Japanese spurge
Fraxinus sieboldiana, Siebold ash
Hosta sieboldiana, Hosta
Juglans sieboldiana, Japanese walnut
Salix sieboldiana, Japanese willow
Sambucus sieboldiana, Japanese red elder
Acer sieboldianum, Siebold’s maple

Siebold Hemlock, Tsuga sieboldii in the past few decades has received renewed interest. Since the late 1980’s North America’s Canadian hemlock, Tsuga canadensis as well as the Carolina hemlock, Tsuga caroliniana have been killed by hemlock woolly adelgid (HWA), Adelges tsugae. These two eastern hemlock species cannot adequately resist or tolerate the destructive feeding impacts of this introduced insect. The results have been widespread deaths of hemlock trees. Along with hopes of finding naturally resistant trees, researchers are also working at developing resistant crosses between North American and Asia species, as has been ongoing for decades with an analogous situation for our American chestnut. Thus far the results to hybridize Canadian hemlock, Tsuga canadensis with three different Asian species have not been successful, but ongoing attempts continue.

On a future visit to Mount Auburn look for a fine Siebold hemlock on Robin Path.

The way a crow

Shook down on me

The dust of snow

From a hemlock tree

Has given my heart

A change of mood

And saved some part

Of a day I had rued.

-Robert Frost

About the Author: Jim Gorman

Visitor Services Assistant View all posts by Jim Gorman →

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