Simaroubaceae 

{{Short description|Family of plants}}

{{Automatic taxobox

| image = Ailanthus altissima2.jpg

| image_caption = Ailanthus altissima

| taxon = Simaroubaceae

| authority = DC.{{cite web |url=http://www.ars-grin.gov/cgi-bin/npgs/html/family.pl?1036 |title=Family: Simaroubaceae DC., nom. cons. |work=Germplasm Resources Information Network |publisher=United States Department of Agriculture |date=2003-01-17 |access-date=2011-04-19}}

| subdivision_ranks = Genera

| subdivision = See text

| synonyms =

• Ailanthaceae J.Agardh
• Castelaceae J.Agardh
• Holacanthaceae Jadin, nom. inval.
• Leitneriaceae Benth. & Hook.f., nom. cons.
• Simabaceae Horan.
• Soulameaceae Endl.

| range_map = Simaroubaceae distribution.svg

| range_map_caption = Distribution of the family Simaroubaceae.

}}

The Simaroubaceae, also known as the quassia family, are a small, mostly tropical, family in the order Sapindales. In recent decades, it has been subject to much taxonomic debate, with several small families being split off. A molecular phylogeny of the family was published in 2007, greatly clarifying relationships within the family.{{cite journal |first=Joshua W. |last=Clayton |author2=Edwino S. Fernando |author3=Pamela S. Soltis |author-link3=Pamela S. Soltis |author4=Douglas E. Soltis |author-link4=Douglas E. Soltis |year=2007 |title=Molecular phylogeny of the tree-of-heaven family (Simaroubaceae) based on chloroplast and nuclear markers |journal=International Journal of Plant Sciences |volume=168 |number=9 |pages=1325–1339 |doi=10.1086/521796|s2cid=86016778 }} Together with chemical characteristics such as the occurrence of petroselinic acid in Picrasma,{{cite journal|author=Tsujimoto, M. |author2= Koyanagi, H. |journal=Bull. Chem. Soc. Jpn.|title=On Nikagi Oil|volume=8|issue=5|date=May 1933|pages=161-167}} in contrast to other members of the family such as Ailanthus,{{cite journal|author=T. Stuhlfauth|author2= H. Fock|author3= H. Huber|author4= K. Klug|title=The distribution of fatty acids including petroselinic and tariric acids in the fruit and seed oils of the Pittosporaceae, Araliaceae, Umbelliferae, Simarubaceae and Rutaceae|journal=Biochemical Systematics and Ecology|volume=13|year=1985|pages=447–453 |doi=10.1016/0305-1978(85)90091-2}} this indicates the existence of a subgroup in the family with Picrasma, Holacantha, and Castela.

The best-known species is the temperate Chinese tree-of-heaven Ailanthus altissima, which has become a cosmopolitan weed tree of urban areas{{cite journal |author=Elizabeth Pan|author2=Nina Bassuk|title=Establishment and Distribution of Ailanthus altissima in the Urban Environment|url=http://www.hort.cornell.edu/uhi/research/articles/jeh4(1).pdf|journal=J. Environ. Hort.|volume=4|issue=1|pages=1-4|date=March 1986}} and wildlands.{{Cite journal|jstor = 3088649|title = Invasion of an Old-Growth Forest in New York by Ailanthus altissima: Sapling Growth and Recruitment in Canopy Gaps|journal = Journal of the Torrey Botanical Society|volume = 127|issue = 4|pages = 307|last1 = Knapp|first1 = Liza B|last2 = Canham|first2 = Charles D|doi = 10.2307/3088649|year = 2000}}

Well-known genera in the family include the tropical Quassia and Simarouba.

It is known in English by the common names of the quassia family or ailanthus family.{{cite book |last1=Brockman |first1=C. Frank |title=Trees of Norh America : A Guide to Field Identification |date=1986 |publisher=Golden Press |location=New York |isbn=978-0-307-63658-4 |page=8 |url=https://archive.org/details/treesofnorhameri00broc/page/8 |access-date=12 January 2025}}