Liquidambar is a genus of four species of flowering trees; L. alcalycina; L. formosana; L. orientalis; and L. styraciflua.

Common name:  Common names of all of the species include ‘Sweet Gum’, with additions according to their native regions. Other names include ‘Chang’s Sweetgum’ (L. alcalycina),’Redgum’, ‘Satin Walnut’ and ‘American Storax’. Both the scientific and common names refer to the sweet resinous sap (liquid amber) exuded by the trunk when cut.

Native areas: L. alcalycina is native to central and southern China; L. formosana to China and other parts of S.E. Asia; L. orientalis to south-west Turkey, Greece and Rhodes; L. styraciflua to the eastern USA, Mexico and Honduras.

Historical notes: The genus was much more widespread in the Tertiary age, but has disappeared from Europe due to extensive glaciation in the north and the east-west orientated Alps and Pyrenees, which have served as a blockade against southward migration. It has also disappeared from western North America due to climate change, and also from the unglaciated (but nowadays too cold) Russian far east. L. styraciflua is the most common species used in the U.K. and was introduced from its native USA in the 17th century. It was awarded the RHS ‘Award of Garden Merit’ in 1975.

Liquidambar styraciflua

‘Lane Roberts’

‘Lane Roberts’

‘Worplesden’

‘Worplesden’

Liquidambar alcalycina

Liquidambar acalycina

Liquidambar orientalis

Features: All Liquidambar are large, deciduous trees, most 25–40 metres (82–131 ft) tall, with palmately 3- to 7-lobed leaves arranged spirally on the stems and length of 12.5 to 20 centimetres (4.9 to 7.9 in), having a pleasant aroma when crushed. Mature bark is grayish and vertically grooved. The flowers are small, produced in a dense globular inflorescence around 1-2 centimetres diameter. The fruit is a woody multiple capsule 2–4 centimetres (0.79–1.57 in) in diameter (popularly called a “gumball”), containing numerous seeds and covered in numerous prickly, woody armatures, possibly to attach to fur of animals. In more northerly climates, sweetgum is among the last of trees to leaf out in the spring, and also among the last of trees to drop its leaves in autumn, turning multiple colors. It is sometimes confused with Maple on account of its similar leaves.

L. styraciflua fruit and leaves

L. styraciflua fruit

L. styraciflua fruit

L. styraciflua bloom

L. styraciflua bark

Uses: All of the species provide incredible autumn colour. In the U.K. they are predominately used as specimens – against a fresh green lawn, their foliage colour really stands out – and as woodland trees. L. styraciflua makes a large tree with a pyramidal crown if its central leader is retained. Its attractive, corky bark is a feature at all times of the year, but it is at its most magnificent in the autumn, when it seems to burn with crimson and gold. Suitable for streets, avenues, parks and largish domestic gardens

There are now several cultivars of  L. styraciflua available:

‘Lane Roberts’– reliable in Britain, this is a medium-sized tree (10-15 metres mature height), with a tighter conical habit and larger leaves than the species. Good in groups for mass effect.

‘Manon Variegata’ – a must for those that like variegated trees, the foliage is best in summer, providing excellent contrast against darker leaved, evergreen backgrounds. Medium height (15- 20 metres mature height), it has regular pyramidal form with horizontal lateral branches.

‘Stella’ – with deeply cut, star-like leaves it is of medium height (10-15 metres) and has glorious autumn colour. best in larger gardens.

‘Thea’ – a broad -leaved and late to colour variety, ‘Thea’ grows conically to 15-20 metres tall. Similar to ‘Lane Roberts’ but taller. Distinctive purple foliage in the autumn.

‘Worplesden’ – unlike most other clones, this variety will often bear fruit in the U.K. This is the variety most often favoured for its autumn colour and form, growing to a mature height of 20 metres plus. It has deeply lobed leaves which turn yellow in September and then turn to orange before falling, but the outermost leaves gradually turn to magnificent claret red. The choice for large gardens.

Liquidambar acalycina

L. styraciflua ‘Lane Roberts’

L. styraciflua ‘Worplesden’

Liquidambar formosana

Growing conditions:  L. styraciflua does best in fertile, well-drained soils, and is the hardiest species, tolerating down to -15 degrees C.  The other species can all be grown in the U.K. but vary in hardiness; down to -5 degs C. There are also hardy forms such as the L. formosana Monticola Group, which could be considered for colder areas. Liquidambar should be planted in full sun in neutral to acid soil that is moist but well-drained- it does not thrive in chalky soils. The genus resents transplanting, but if this is unavoidable, prepare by root-pruning a year in advance.

Further information:

Wikipedia- Liquidambar

RHS- Liquidambar styraciflua

Horticulture Week- Liquidambar

Gardener’s World- Liquidambar

Barcham Trees Directory- Liquidambar styraciflua ‘Worplesden’

Old School Gardener