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Ulleungdo Hemlock

Tsuga ulleungensis

Accession Number
The alpha-numeric value assigned to a plant when it is added to the living collection as a way of identifying it.
Accession Date
The year the plant’s accession number was assigned.
Common Name
The non-scientific name for the plant.
Scientific Name
The scientific name describes the species of an organism. The first word is the plant's scientific genus and the second is the specific epithet. This two-word binomial is sometimes followed by other taxonomic descriptors, including subspecies (denoted by "ssp."), variety (denoted by "var."), form (denoted by "f." or "forma"), and cultivar (denoted by single quotation marks).
Plant Family
The family to which the plant belongs.
Propagation Material
The first part (material code) describes the material used to create the plant. The most common codes are "SD" (seed), "EX" (existing plant), "PT" (plant), "CT" (cutting), "SC" (scion), "SG" (seedling), and "GR" (graft). The second part describes the lineage the plant is derived from. The last part describes the year of propagation.
Collection Data
The first part indicates provenance (place or source of origin) using a letter code ("W" = wild, "G" = garden, "Z" = indirect wild, "U" = uncertain). The second part lists the plant source. For wild-collected material, the collector, collection number, and country are given.
The location of the plant on the landscape.
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Tsuga ulleungensis
SD - LINEAGE 1251-83
Ulleungdo Hemlock

In 2003, a researcher collected a sample from this tree and its nearby sibling. Genetic analysis revealed something surprising—the trees didn’t match other hemlocks bearing the same name.

Sometimes scientific discovery comes through serendipitous means. Seed for this tree arrived at the Arnold Arboretum in 1983. It was a gift from the Chollipo Arboretum, in South Korea, which had obtained the seed on Ulleungdo—a volcanic island in the center of the Sea of Japan. The seeds were labeled as southern Japanese hemlock (Tsuga sieboldii), and as this tree and its nearby sibling spread their branches on the grounds at the Arnold Arboretum, this name was retained.

Then, in 1997, an invasive insect known as the hemlock wooly adelgid (Adelges tsugae) arrived at the Arboretum. Its range had spread northward from its original introduction site near Richmond, Virginia, and as it did so, researchers increasingly began to study the insect, searching for ways to mitigate its devastation to North American hemlock forests. A graduate student from Yale University, Nathan Havill, came to the Arboretum in 2003 to harvest samples from the well-documented and diverse hemlock collection. One of his dissertation advisors, Michael Donoghue, suggested that to understand the insect, one must also understand the plants.

Havill’s genetic work suggested that these hemlocks from Ulleungdo were distinct from other southern Japanese hemlocks. This discovery prompted Peter Del Tredici, who is now a senior research scientist emeritus at the Arboretum, to dig deeper. In 2008, Del Tredici visited Ulleungdo with colleagues—both American and South Korean researchers—to collect from additional populations of hemlocks. For the resulting genetic research, Del Tredici turned to Garth Holman, a graduate student at the University of Maine, and in 2014, when Holman’s dissertation was complete, his results suggested that these Ulleungdo hemlocks warranted treatment as a new species. In 2017, the new name was officially published: Tsuga ulleungensis.

Del Tredici was not the first Arboretum staff member to visit Ulleungdo. The well-known plant collector Ernest Henry Wilson visited the island in the spring of 1917. His colleague Takenoshin Nakai guided him, and Wilson collected herbarium specimens of the hemlocks and took photographs of the trees. Both Wilson and Nakai referred to the trees as the southern Japanese hemlock (Tsuga sieboldii). Incidentally, even though these two species look almost identical to one another, Holman’s research showed that the Ulleungdo hemlock is more closely related to the northern Japanese hemlock (T. diversifolia).

Altogether, this story is testament to the research value of a well-documented plant collection. Without records of the origin of this anomalous tree at the Arnold Arboretum, the mystery of the Ulleungdo hemlock might have never been resolved.

South Korea

Viewing this plant in-person? Look for these defining characteristics:

  • 1
    Flat needles Jonathan Damery
  • 2
    Broad, v-shaped branching pattern Peter Del Tredici
  • 3
    Cones showing bracts with diagnostic rounded margins Peter Del Tredici

About Our Collection

Fun Facts

  • The Ulleungdo hemlock can be distinguished from the southern Japanese hemlock (Tsuga sieboldii) by the larger size of its leaves and petioles and the wave-like (versus finely toothed) teeth on the cone scale bracts.

  • Geological records indicate that the Ulleungdo region emerged from the ocean floor some 2.7 million years ago and that it has supported plant life for the past 1.7 million years.

  • Ulleungdo is known to harbor some 33 other endemic species or subspecies of plants.


Living Specimens
Specimens Dead or Removed
First Addition
Most Recent Addition
Tallest Specimen

Living Specimens

Plant ID Accession Date Received As Origin Source

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