The Latin species name of the American sweetgum tree, Liquidambar styraciflua, means something like “liquid amber”. In fact, this very apt name not only refers to the fact that the aromatic resin of the genus is used for the production of chewing gum (which is why the deciduous tree is also called “sweetgum” or “redgum” in its native land), but also to the bright red-orange color in autumn Foliage glows golden in the sun. Due to its decorative effect, the sweetgum tree is enjoying growing popularity as a medium-sized house and park tree.
What is the sweetgum tree known for and how is it used?
The sweetgum tree (Liquidambar styraciflua) is a North and Central American deciduous tree valued for its bright red-orange autumn leaves and aromatic resin. In Europe it is used as an ornamental and park tree, while in its homeland it is used as a raw material for chewing gum, furniture and cosmetics.
Origin and distribution
The American sweetgum tree has its home in North and Central America, where it is mainly at home in river valleys and on mountain slopes between the state of New York and the Central American state of Nicaragua - provided that the subsoil there is nutrient-rich, deep and rather fresh to moist.
The species belongs to the genus of sweetgum trees (Liquidambar), which was previously classified as a member of the witch hazel family (Hamamelidaceae). However, botanists now believe that the group forms its own, very small plant family, Altingiaceae, with only about 15 species. Sweetgum trees are therefore not only native to North America, some species also thrive in the Mediterranean region (Oriental sweetgum tree, Liquidambar orientalis) as well as in East and Southeast Asia (for example the Formosan sweetgum tree, Liquidambar formosana).
In Europe, however, the American sweetgum tree is primarily cultivated as an ornamental and park tree. The species came to the Old World as early as 1681, and many varieties with different growth and height are now available.
Usage
While the American sweetgum tree is mainly cultivated in private gardens and public parks as an ornamental tree, it is a valuable commercial tree in its homeland. Not only is the sweet-smelling storax, as the resin of the species is also called, an important raw material for the production of chewing gum and is used in natural medicine, but also the hard wood of the sweetgum tree, which is very similar in grain and color to walnut wood very popular in furniture manufacturing.
Furthermore, the aromatic-smelling amber tree wood and its resin also serve as raw materials for the production of perfumes, soaps and other cosmetics. Although the resin of the tree is called "Storax", the sweetgum tree is in no way related to the actual Storax tree (Styrax americanus) - it simply replaced it in the 18th century in resin extraction.
Appearance and growth
In their homeland, wild specimens of the sweetgum tree reach heights of up to 45 meters. This makes the species one of the tallest-growing deciduous trees, but in Central Europe it usually does not reach more than around 20 meters, even in regions with mild climates. In addition to the tall species, there are some significantly smaller varieties available that reach heights of between around four and a maximum of ten meters and are therefore also suitable as house trees for private gardens.
When young, the sweetgum tree has a conical, rather narrow growth, but can grow significantly wider as it gets older. The initially red-brown bark later turns grey-brown and develops a wide furrow as well as the cork strips that are characteristic of the species.
leaves
The sweetgum tree has another name, which it owes to its maple-like leaves: it is called the starfish tree because the five to seven-lobed, palmate leaves are strongly reminiscent of sea creatures. Laypeople often confuse the sweetgum tree with the native maple tree due to the shape of its leaves.
During the summer months, the up to 15 centimeter long, alternately arranged leaves are shiny green, but often take on their wonderful autumn color from the end of September. Nature seems to dig particularly deep into the color pot of the sweetgum tree, as the color palette ranges from yellow-orange to orange-red and carmine red to violet tones. This broad coloration can often even be observed on the same tree.
This makes the American sweetgum tree one of the garden trees with the most beautiful autumn foliage, which is also the main reason for its popularity as a house and ornamental tree. By the way, the leaves also give off their characteristic aromatic scent when you rub them gently between your fingers.read more
Bloom and flowering time
The rather inconspicuous blossom of the sweetgum tree appears in the wonderful month of May. The species is monoecious and develops both female and male flowers on the same plant. Male flowers resemble upright, greenish spikes and are about five to seven centimeters long. The female inflorescences, on the other hand, sit on chestnut-like, hanging balls. Pollination occurs via insects.
Fruits
At first glance, the spherical fruits of the sweetgum tree, which have long spines, resemble the fruit capsules of the chestnut. However, they are significantly smaller, with a diameter of two to three centimeters, and they are also made up of numerous woody capsules. Amber trees only produce fruit when they are around 20 years old. These stay on the tree for a long time and often only fall to the ground in spring.
The brown fruit bursts open on the ground so that the small seeds fall directly to the ground. However, most of it is not germinable and therefore cannot be used for propagation. You can recognize the sterile seeds because they are noticeably small and have a rather angular shape. Only a few seeds are fertile and therefore able to germinate. They are significantly larger, have an elliptical shape and membranous wings with which the wind carries them to possible new locations.read more
Toxicity
Although the gum tree resin is still an important raw material for the production of natural medicines and chewing gum, it is only harmless after it has been processed industrially. Otherwise, all parts of the plant are considered to be irritating to the skin and mucous membranes or even poisonous for both humans and animals, although symptoms of poisoning can occur particularly in children and small pets.
Which location is suitable?
As in its natural locations, a sweetgum tree cultivated in the garden also needs a location in full sun and as warm as possible. It is best to plant the tree in a place protected from wind and rain in front of a bright house wall or wall, which is also ideally facing south. Here the tree gets enough sun and protection, which it needs especially in the first few years - the species only develops its frost hardiness as it gets older. Wind protection is also important because the sweetgum tree loses its protective foliage quite early in the year.
On the other hand, even in a partially shaded to slightly shaded location, a spot is usually too dark. The species only produces its colorful autumn leaves in very sunny and warm locations.read more
Floor
The optimal soil for the American sweetgum tree is deep, loose and well-drained, moderately nutrient-rich to humus-rich and fresh. Ideally, you should plant it in loamy soil, as the species does not tolerate both poor, sandy soils and calcareous subsoils particularly well. While the sweetgum tree only grows very slowly on sand, it quickly develops unhe althy yellow leaves on chalky soil. Waterlogging in turn leads to rot and thus the death of the tree.
pot culture
Since the sweetgum tree is very sensitive to cold, wind and other weather influences in the first few years, you should first cultivate it in a large container and gradually get used to the climatic conditions. In the long term, however, the tall species cannot be kept in a planter without having to severely restrict its growth. Sweetgum trees grown as bonsai, for example, require a lot of attention and care.
Planting the sweetgum tree correctly
Plant the sweetgum tree as follows:
- Dig a planting hole.
- This should be twice as wide and deep as the root ball.
- Loose up the soil on the sides and bottom of the hole.
- Mix the excavated material with compost (€12.00 on Amazon) and horn shavings/horn meal.
- In heavy soil, install drainage, such as pebbles.
- Insert the tree so deep that the grafting area is covered with soil.
- Plant a supporting stake.
- Connect this securely to the trunk, e.g. B. with a raffia ribbon.
- Fill the planting hole and carefully tamp down the soil.
- Slurry the fresh soil with plenty of water.
- Mulch the root disc so that the soil does not dry out.
read more
What is the best time to plant?
Basically, the sweetgum tree can be planted in both early autumn and late spring. However, since young specimens in particular are quite sensitive to cold and wind, you should prefer spring.read more
The correct planting distance
Since sweetgum trees can grow up to 20 meters high and eight meters wide when fully grown, they need a lot of space. Therefore, the species is only suitable for a solitary position in the garden that meets these requirements - especially since transplanting it in later years becomes difficult or impossible. Furthermore, the sweetgum tree is very easy to cut, but depending on the variety it is also quite fast-growing and therefore difficult to limit in height and width with secateurs.
Underplants
Amber trees have loose growth and allow a lot of light to pass through their crown. That's why they can be planted well with ground cover plants and other perennials, as long as they don't compete too much. For example, onion flowers that bloom in spring, such as tulips and daffodils, are very suitable, but also monkshood, autumn anemones, forest bluebells and hostas.read more
Watering the amber tree
Specimens grown in pots obviously need to be watered regularly during the growing season as they cannot take care of themselves. Even freshly planted and young sweetgum trees can be given a spray from the watering can in dry weather. Older, already well-established trees, on the other hand, can do without additional watering.
Fertilize the sweetgum tree properly
The same applies to the supply of fertilizer: Only young trees benefit from spring fertilization with compost (€12.00 on Amazon) and horn shavings to accelerate their slow growth. However, for older, well-rooted sweetgum trees, additional nutrient supply is not necessary.read more
Cutting the amber tree correctly
Amber trees are very tolerant of pruning and can therefore be kept as a bonsai or as a pot culture for a few years. In contrast to fruit trees, however, regular maintenance or care pruning is basically unnecessary, as such a measure affects the natural growth habit. It's best to just let the tree grow and only remove dead, diseased and dense wood in the spring.read more
Propagate sweetgum tree
As a rule, sweetgum trees are propagated through grafting, but can also be grown from seeds. In contrast to refined specimens, seedlings are unpredictable in their properties, and only a few of the mature seeds are actually capable of germinating. For sowing, choose only large, elliptical-shaped seeds.
These need a cold stimulus to break the germination inhibition. Store the seeds in the vegetable drawer of the refrigerator for about two months or sow them in a covered cold frame in the fall. From spring onwards, the seeds require constant temperatures of 20 °C or more for germination and growth.read more
How do I transplant correctly?
Once planted, sweetgum trees should only be transplanted within the first three to a maximum of five years. After that, they usually tolerate a change of location very poorly.
Diseases and pests
Diseases and pest infestations only occur very rarely on the sweetgum tree. On the other hand, typical location and care errors, such as
- in too dark locations
- compacted or otherwise unsuitable soil
- if it is too dry
- if fertilization is insufficient
- as well as waterlogging
occur. Affected trees develop yellow to brown leaves that are shed after a while. In addition, they grow very poorly. Since sweetgum trees are very sensitive, they can die quickly, especially as a result of too little/too much water.
Wintering
In Central Europe, only the American sweetgum tree is sufficiently hardy; both the Oriental and the Asian Formosan sweetgum tree come from mild winter climates and are therefore not tolerant of frost. However, the American relative only develops its frost hardiness with increasing age, which is why some experts recommend pot cultivation and gradual hardening, at least for young trees. Later, when the tree is planted out, it will receive winter protection for the first few winters. To do this, cover the root area with brushwood, mulch or straw and, when temperatures are below zero, also wrap the trunk with garden fleece. However, the tree later develops sufficient frost hardiness.
Tip
It is best to leave the leaves that are shed in autumn: they not only serve as natural winter protection, but also provide the tree with valuable nutrients through the rotting process.
Species and varieties
Only the American sweetgum tree (Liquidambar styraciflua), which can withstand temperatures of up to minus 24 °C in sheltered locations, is hardy in this country. There are now some beautiful varieties of this species available that are wonderfully suitable for the home garden:
- 'Gumball': weak-growing variety with a maximum height of two meters and a spherical crown
- 'Oktoberglut': very popular variety with bright, colorful autumn colors and a maximum height of three meters
- 'Variegata': white and variegated foliage, maximum height of two meters, perfect for permanent container storage
- 'Worplesdon': slow growth, up to a maximum height of ten meters, fire-red autumn color
- 'Silver King': also variegated white foliage, bright red autumn color, maximum height of five meters
- 'Slender Silhouette': slim column shape with a maximum width of one meter, wonderful for small gardens
Other types of sweetgum such as the Chinese sweetgum (Liquidambar acalycina), the Oriental sweetgum (Liquidambar orientalis) or the Taiwanese sweetgum (Liquidambar formosana), however, are not suitable for planting in Central European gardens, but can be grown in sufficiently large ones Pots as well as with a lot of careful care in winter gardens or outside during the summer months.
