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1927 Map of the Arboretum

Plant Introductions

Hamamelis x intermedia 'Arnold Promise' 195-2005*A in full flower in late winter. William (Ned) Friedman
Hamamelis x intermedia 'Arnold Promise' 195-2005*A in full flower in late winter.


This list of introductions spans the past 150 years of our horticultural contributions. This century-and-a-half of advancing the mission can be divided into three fifty-year eras, each defined by the unique character and interests of Arboretum leaders at the time. Entries share the anecdotes of an individual introduction, and together, they tell the story of the Arboretum and its plants through these three eras.

Fun Facts

  • The process of scientific inquiry at the Arnold Arboretum has led to the development of well-known introductions. Former director and scientist, Professor Karl Sax’s plant breeding research, which spanned the 1930s through the 1950s, resulted in Forsythia ‘Arnold Giant’ and Forsythia ‘Arnold Dwarf’. His work in the crabapple collection yielded Malus ‘Mary Potter’ and numerous other excellent crabapples, some of which are yet to have been fully evaluated and named.

    A black and white photo of Karl Sax with a dwarf apple tree.
    In this 1959 photo by Heman Howard, Karl Sax is seen with a grafted dwarf apple tree, one of his many research interests at the Arboretum. Archives of the Arnold Arboretum
  • Introductions of the Arnold Arboretum would not have been so successful and numerous without the keen observations and enthusiastic promotion by the Arboretum’s agents. Cultivars Malus ‘Dorothea’, found by arboretum horticulturist Donald Wyman, and Stewartia ‘Scarlet Sentinel’, found by director of the living collections and researcher Peter Del Tredici, were discovered as chance seedlings growing among the living collections. Wyman was a champion of Arboretum introductions, promoting and distributing plants far and wide. Del Tredici oversaw the Arboretum’s first formal Plant Introduction Promotion and Distribution program (PIPD) between 1996 – 2001.

  • Many introductions were developed in collaboration with Arnold Arboretum’s friends and neighbors, who observed plants with unique traits in their gardens. Magnolia × thompsoniana ‘Cairn Croft’, a cultivar of the first described hybrid magnolia, is a product of such a partnership. It was brought to the Arboretum in 1998 by Kevin Doyle, a horticulturist on an estate in nearby Westwood, Massachusetts. It was introduced by Peter Del Tredici, then senior research scientist at the Arboretum, in 2006.

    William (Ned) Friedman
  • Throughout the Arboretum’s history, expeditions have led to the introduction of many valuable ornamental plants, though sometimes the process of identifying a plant with potential and the importation of viable seeds can span decades. The original specimens of the seven-son flower, Heptacodium miconiodes, were sent as herbarium specimens by explorer Ernest Henry Wilson in 1907. During the 1980 Sino-American Expedition Stephen Spongberg, then director of the Arboretum, collaborated with a team of scientists and returned with viable seed from the Hangzhou Botanical Garden in China. Softwood cuttings from these seedlings were distributed throughout North America by the Arboretum in 1986.

    Jon Hetman

Arnold Introductions

Since the founding of the Arnold Arboretum in 1872, the institution has contributed to the expansion of the horticultural palette for American gardens, bringing to cultivation plants that have now become familiar and beloved. This mission of plant introduction has taken many forms over the past 150 years: Arboretum plant explorers have brought back species that had never been grown in North America, while horticultural researchers have bred, selected, and named novel forms originating at the Arboretum. Arnold Selects, the Arboretum’s new plant introduction program, blends the art and science of horticulture to share storied plants from the living collections.
Magnolia stellata 'Centennial' (170-2002*A). Tiffany Enzenbacher


  • 1977-present

  • 1928-1976

  • 1874-1927

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