Tag Archives: ailanthus altissima

Tree of Heaven: Invasiveness, Immigration, and Racism

I like to call Ailanthus altissima the tree of good or evil. Depending on your perspective, it is either the “ghetto palm,” an invasive pest, or the “tree of heaven,” a tough, hardy street tree once planted for its beauty.

Introduced into the United States from China in 1748, it was being planted as a street tree by the 1820s. Pollution-resistant, salt-tolerant, quick-growing, and with tropical-like foliage, what was not to love about this tree?

Ailanthus with green fruit
Typical greenish-yellow fruit of Ailanthus

Peter Del Tredici, senior research scientist at the Arnold Arboretum, held a tree mob on July 22 on a specimen of this tree (accession #695-80-B). Before eventually turning brown, most ailanthus trees have fruit that go from green to yellow. The tree that Del Tredici collected goes from green to red, hence the form “erythrocarpa,” which means red fruit. Del Tredici described the red on the tree as a spontaneous mutaton that appears sporadically.
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Last to Leaf Out

Spring has arrived early this year. The lilacs are in bloom. And most of the trees at the Arnold Arboretum have either bloomed or started to leaf out.

Lilacs at the Arnold Arboretum
Lilacs blooming at the Arnold Arboretum

A few species still wait cautiously. Among those that have yet to wake:

  • Ailanthus altissima — Tree of Heaven
  • Albizia julibrissin — Silktree/Mimosa
  • Catalpa ovata — Chinese Catalpa
  • Fraxinus excelsior — European Ash
  • Gymnocladus dioica — Kentucky Coffeetree
  • Rhus chinensis — Chinese Sumac
  • Robinia pseudoacacia — Black Locust
View from the top of Peters Hill
View from the top of the Arboretum's Peters Hill
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