Ailanthus

Ailanthus (/əˈlænθəs/;[1] derived from ailanto, an Ambonese word probably meaning “tree of the gods” or “tree of heaven”)[2] is a genus of trees belonging to the family Simaroubaceae, in the order Sapindales (formerly Rutales or Geraniales). The genus is native from east Asia south to northern Australasia.

The number of living species is disputed, with some authorities accepting up to ten species, while others accept six or fewer. Species include:

Ailanthus altissima (Mill.) Swingle (tree of heaven, syn. A. vilmoriniana Dode[3]) – northern and central mainland China, Taiwan. Invasive in North America, Europe, Britain, and Australia.[4][5] Serves as central metaphor in A Tree Grows in Brooklyn.
Ailanthus excelsa Roxb. – India and Sri Lanka
Ailanthus fordii Noot. – China
Ailanthus integrifolia Lam. – New Guinea and Queensland, Australia
Ailanthus triphysa (Dennst.) Alston (white siris syn. A. malabarica[6]) – India, South-east Asia and Australia
Ailanthus vietnamensis H.V.Sam & Noot. – Vietnam
There is a good fossil record of Ailanthus with many species names based on their geographic occurrence, but almost all of these have very similar morphology and have been grouped as a single species among the three species recognized:[7]

Ailanthus tardensis Hably – from a single locality in Hungary
Ailanthus confucii Unger – Tertiary period, Europe, Asia, and North America
Ailanthus gigas Unger – from a single locality in Slovenia
Ailanthus pythii Unger – known from the Miocene of Iceland, Styria in Austria and the Gavdos island in Greece
Ailanthus kurzii Prain – endemic to the Andaman Islands, India