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‘Ernest Wilson’ Silk Tree

Albizia julibrissin ‘Ernest Wilson’

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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Albizia julibrissin ‘Ernest Wilson’
SD - LINEAGE 13381
WILSON, E. H. 11245
‘Ernest Wilson’ Silk Tree

In 1918, Arboretum plant collector E.H. Wilson stumbled upon an interesting silk tree in a Korean hotel courtyard. Few thought this species could survive New England’s bitter winters, but Wilson collected seeds regardless. Surpassing expectations, one of that tree’s unique offspring now resides in our Explorer’s Garden, now over a century old—and still growing.

In 1918, plant collector Ernest Wilson and his family returned to the Korean Peninsula. Wilson was in the middle of a three-year plant collecting expedition, acquiring seeds and small plants for the Arnold Arboretum. During his family’s stay at the Chosen Hotel in Seoul, Wilson observed an unusual silk tree in the courtyard garden. Although this species is common in warm climates across Asia, he had seen none growing in cooler, central Korea. He gathered seeds, hoping that this individual might yield offspring similarly suited for chilly New England winters.

Wilson’s hunch paid off. In 1923, horticulturists planted a small sapling grown from these seeds in the Arboretum’s Explorer’s Garden. Expectations must have been low, as earlier attempts at growing silk trees at the Arboretum had ended in failure. However, this one survived. A surprised Wilson declared it “astonishing that this tree should be able to withstand New England winters.” That sapling is now over a century old, unprecedented for a species with a typical lifespan of just a few decades.

Cold tolerance and longevity turned out to be just two of this silk tree’s unique features. Unlike other specimens, Wilson’s introduction is shorter in stature, with a low hanging canopy. The tree also boasts stunning, bright pink floral highlights of a much richer hue compared to others. In 1968, the Arboretum named this distinctive silk tree cultivar Albizia julibrissin ‘Ernest Wilson’, in honor of his contributions.

This globe-spanning success story exemplifies the Arboretum’s renowned history of plant exploration and introduction. However, in some ways, it is also emblematic of a Western-centric chapter of plant collecting. The hotel courtyard garden origin of the mother silk tree implies that Korean horticulturists perhaps intentionally selected it for cold tolerance. Modern sensibilities suggest honoring the Koreans who at some point began the cultivation process (and cared for the tree he collected from) rather than Wilson alone.

Cultural changes apply to plant collecting methods as well. Although once an extremely fashionable garden addition, particularly in Europe and the American south, the silk tree quickly escaped cultivation. Today, many southern and south-western US states categorize the silk tree as an invasive species. Although not considered invasive in Massachusetts, Arboretum staff nonetheless learned from the example of other invasives that did take hold. Present-day plant collectors carefully consider invasive potential before introducing new species into our landscape. Importing foreign species and seeds is also now strictly regulated by the U.S. government.

In any case, the Arboretum’s six silk trees (including two specimens of the Wilson cultivar) serve a valuable function in our living museum. During cold winters, blanketed thick with winter snow, they teach us valuable lessons about biological adaptation, horticultural ingenuity, and global plant collecting. Late summer afternoons, on the other hand, offer a moment for philosophical musing. On these days, our silk trees’ pink and white flowers attract crowds of visitors and staff expressing admiration and, sometimes, disdain. As the wind blows, you can almost hear the silk trees talking as well, about the mysterious human love for plants, the fascinating complications of our desires.

South Korea

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

  • 1
    Pink and white silk tree flower
    Silky pink and white flowers William (Ned) Friedman
  • 2
    Feathery leaves William (Ned) Friedman
  • 3
    Long green pods and feathery leaves
    Long pealike seed pods William (Ned) Friedman
  • 4
    Multiple leaders, or central trunks Suzanne Mrozak
  • 5
    Low canopy Kyle Port

About Our Collection

Fun Facts

  • The English common name “silk tree” is a mostly Western hemisphere reference to this plant’s silk-like flowers. However, throughout much of its native range, this species is widely known as the “sleeping tree”. This refers to its leaflets, which fold together each night like a couple getting into bed.

  • “Mimosa tree” is an accepted common name in parts of the United States. This refers to the species’ historical (and incorrect) inclusion in the plant genus Mimosa. Although silk tree flowers look like a party, the colorful mimosa cocktail is named after a different plant: Acacia dealbata.

  • The plant’s genus name Albizia honors Italian nobleman Filippo degli Albizzi, who collected seed in Constantinople (present day Istanbul) and introduced the species to Italy in 1745. The preponderance of European botanical naming for much of the world’s plants broadly reflects patterns of European centric exploration and colonization.

  • Asian physicians historically prescribed silk tree tea (made from both leaves and flowers) as a healing remedy. However, in the West, the seeds are reported toxic.

  • The silk tree is renowned as a pollinator plant, attracting bees and hummingbirds during its long summer blooming period.


Living Specimens
Specimens Dead or Removed
First Addition
Most Recent Addition
Tallest Specimen
There are six silk trees in the Arboretum’s collection. Two of these are the cultivar ‘Ernest Wilson’.
Five of our silk trees were collected in South Korea. The sixth came from the Lushan Arboretum in China.
Our oldest accessioned tree is over a century old, while the youngest was accessioned in 2013. The average lifespan for this species is usually several decades, and it is known for being short-lived.
Silk trees are renowned for having weak wood. The main trunk on our centenarian tree broke apart many years ago. However, new growth sprouted from the base and continues growing today.

Living Specimens

Plant ID Accession Date Received As Origin Source