In short
- One of the finest autumn trees — the leaves blaze purple and red.
- Star-shaped, palmate leaves resemble maple but are arranged alternately.
- Best colour in a sunny site and on acidic, moist soil.
- Spherical, spiky fruit clusters hang on for a long time and drop in winter.
- A large park tree — needs space and is sensitive to limy soils.
Botanical data
- Family
- Altingiaceae (Altingiaceae)
- Height
- 15–25 m
- Width
- 8–12 m
- Habit
- Conical
- Growth rate
- Moderate
- Position
- Full sun, Partial shade
- Soil
- Loamy, Humus-rich, Sandy
- pH reaction
- pH 5–7
- Moisture
- Moderate, Moist
- Bloom
- April–May
- Hardiness
- USDA 5a–9b
- Propagation
- From seed, From cuttings
Characteristics
Young trees have a distinctly conical crown, broadening with age. The leaves are palmately lobed (usually 5–7 lobes), glossy and fragrant when crushed. Autumn colour can be multicoloured on a single tree. The fruit clusters are woody, spiky balls, popularly called gumballs in the USA. The bark of older trunks often forms corky ridges.
Growing and care
Watering
It grows naturally on moist soils and tolerates occasional flooding. Water young specimens in drought so they do not shed leaves.
Fertilizing
Moderately; mulching maintains the acidic, moist character that favours colouring.
Planting
Deep, fertile, rather acidic soil. On limy soils the leaves become chlorotic and the autumn colours are weaker.
Pruning calendar
Pruning group: Deciduous trees — pruning during dormancy
What and how to cut
Prune from late autumn to early spring, on frost-free days. Remove dead, diseased, damaged and crossing shoots, along with competing leaders, leaving one main leader. Prune sparingly. Make the cut just beyond the swollen branch ring (collar) at the base of the branch — not flush with the trunk and without leaving a stub; a wound like this heals over best.
In winter, during dormancy.
What not to do
Do not remove large limbs without a clear need, and for thick, tall trees leave the pruning to arborists. Do not prune in early spring when the sap starts to rise, or during frost. In a single season, do not remove more than roughly a quarter of the crown.
Companion plants
Good companions
They share a liking for acidic, humus-rich and moist soil and flower in spring in the tree's shade.
They use the moist, fertile substrate under the crown and enliven it in early spring, before the sweetgum greens up.
Bad companions
Sweetgum needs acidic, moist soil, so the conditions do not suit plants that prefer dry, limy substrate.
The evidence level indicates whether the relationship is backed by research, observation, or gardening tradition.
Toxicity
| For whom | Level | Notes |
|---|---|---|
| Humans | None | — |
| Dogs | Mild | — |
| Cats | Mild | — |
History and origin
The genus name Liquidambar (liquid amber) and the epithet styraciflua (flowing with storax) refer to the aromatic resin storax, extracted from the bark and used in perfumery and folk medicine. It has been valued as an ornamental in Europe since the 17th century.
Uses
An excellent specimen tree for large gardens, parks and avenues, planted mainly for its spectacular autumn colour. It needs space and an acidic, moist substrate; unsuitable for small plots and limy soils.
Trivia
- The aromatic resin (storax) was once used as incense, a balsam ingredient and chewing gum by American settlers.
- Despite the maple-like leaves it is not a maple — in sweetgum the leaves are arranged alternately, in maples oppositely.
Frequently asked questions
How does sweetgum differ from maple?
The leaves of both are palmately lobed and similar, but in sweetgum they are arranged alternately, in maples oppositely. Sweetgum also bears the distinctive spherical, spiky fruit clusters that maples lack.
Why does my sweetgum colour poorly?
The most common causes are too shady a site and limy soil. Sweetgum colours best in full sun on acidic, moist ground; on alkaline soil the leaves become chlorotic.
Is sweetgum suitable for a small garden?
Not really. It grows to 15–25 m tall and spreads widely with time, so it needs space. For smaller gardens choose slower-growing, columnar cultivars.
Sources
- Plants of the World Online (POWO)Database (GBIF, POWO…)
- RHS — Liquidambar styracifluaInstitution / botanical garden
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