Plant 202

Liquidambar styraciflua L. (Altingiaceae)



Liquidambar is a small genus of deciduous trees with smooth, shiny, maple like leaves. Liquidambar leaves are often mistaken for those of maples but are easy to distinguish because the latter are arranged opposite each other. Although there are only four species in the genus Liquidambar, they are remarkably widely distributed, with species native to Turkey, Central and North America and China. The fossil record reveals an even more widespread distribution, particularly in the Tertiary period (66-2.5 million years ago). Glaciation and climate change led to the genus's disappearance from western North America, Europe and the Russian Far East.

Liquidambar styraciflua is native to south-eastern United States and Mexico and goes by many common names in addition to sweetgum. One of its common names, alligator-wood, derives from its distinctive reptile-like, corky bark. The common name sweet gum derives from the pleasantly fragrant resinous sap that exudes from the bark when the tree is damaged. The sap, known as storax, has been used for hundreds of years to treat common ailments such as skin problems and respiratory congestion. More recently, storax has proven to have antibacterial properties and effective even against multidrug resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). In addition to the sap, the leaves, bark, and seeds of sweetgum also possess beneficial compounds such as shikimic acid, a precursor to the active ingredient in Tamiflu, an antiviral drug effective against several influenza viruses.

The species is grown predominantly as a medium-sized ornamental tree. It has a pleasing symmetrical shape and striking and long-lasting autumn colour. Leaf colour varies from pale yellow to smoky purple through a range of intense reds and oranges. Garden varieties have wonderfully evocative names such as 'Golden Treasure' and 'Moonbeam'.

The species was first introduced into the United Kingdom in the seventeenth century by the Oxford-educated clergyman and plant collector John Banister. Banister was sent to the United States as a naturalist and missionary by the plantsman Bishop Henry Compton. The first specimens were grown in the Fulham gardens of the Bishop's London palace.

Liquidambar styraciflua is one of the most important commercial hardwoods in the south-eastern United States. The timber produced is not particularly hardwearing but can be used for furniture making. The hardwood veneer, also known as satin walnut, has an attractive grain and can be produced in a range of beautiful natural colours ranging from bright reddish brown to almost white.

Further reading

Bean WJ 1973. Trees and shrubs hardy in the British Isles. Vol. 2. John Murray.

Lingbeck JM et al. 2015. Sweetgum: an ancient source of beneficial compounds with modern benefits. Pharmacognosy Review 9: 1-11.

Sarah Lloyd