The Golden Chain Tree, also known as Laburnum or the Golden Rain Tree, is a small deciduous tree or large shrub native to the mountains of southern Europe from France to the Balkans. It belongs to the genus Laburnum and is part of the pea family, Fabaceae.
In late spring, when in bloom, it produces cascading chains of pea-like, yellow flowers densely packed in pendulous racemes. These racemes can reach lengths of 10 to 24 inches. The tree blooms for about 2 to 3 weeks, depending on the weather conditions. In other words, flowers resembles golden chains or golden rain, which is where it gets its common names.
The Golden Chain Tree is a fast-growing plant, adding 2 to 3 feet to its height each season. The tree grows to a height of 15 to 30 feet and spreads equally. The leaves are trifoliate, similar to clover, and are generally oval with long petioles. The bark is smooth and olive green.
It prefers full sun in the first half of the day and partial shade in the afternoon. The tree is hardy down to USDA Zone 5 but is not recommended for zones USDA 7 and above due to its susceptibility to heat and humidity. The tree prefers organically rich, well-drained soils and should be pruned after the blooming period to maintain its shape and size. The seedpods should be removed as they appear to encourage more flowers the following year and prevent the tree from sapping its strength.
There are two main species of Laburnum: Laburnum anagyroides (Common Laburnum) and Laburnum alpinum (Alpine Laburnum).
- Common Laburnum (Laburnum anagyroides): This is the most well-known variety and the parent of many hybrids. It can grow up to 30 feet tall and has bright yellow flowers.
- Alpine Laburnum (Laburnum alpinum): This is a smaller species, only reaching 15-20 feet tall. It has yellow flowers with brownish-purple markings on the wings.
The most popular Golden Chain Tree grown in landscapes is Laburnum x watereri. Golden chain tree (Laburnum x watereri) is a hybrid cross between the common laburnum (Laburnum anagyroides) and the Scotch laburnum (Laburnum alpinum). These two species are native to the mountains of southern Europe from France to the Balkans, and they were first described by the Swedish botanist Carl Linnaeus in the 18th century.
The hybrid, Laburnum × watereri, was first created by the nurseryman Waterer at the Knap Hill Nursery in England in the 19th century. This hybrid is often preferred by many for its low seed production and long pendulous clusters of bright yellow flowers.
The Golden Chain Tree has been widely planted in other regions of the world as an ornamental tree. In the United States, for example, it is sometimes confused for the similarly named, similarly-looking golden rain tree. The tree is beautiful when in full bloom with fragrant golden-yellow, 10- to 20-inch floral sprigs in late spring.
It’s worth noting that all parts of the tree are extremely poisonous, including the seeds, leaves, bark, and flowers. The seeds contain cytisine, an alkaloid that is harmful to humans, goats, and horses, especially when not ripe.
The Golden Chain Tree is not only a beautiful ornamental plant but also has a history of use in woodworking, where its wood is valued for its strength and smoothness. It has been used in making musical instruments, inlays, and veneers on furniture.
Characteristics of Golden Chain Tree
- Size and Growth Rate: The tree grows to a height of 10 to 15 feet in cultivation, with a vase-shaped crown. It has a relatively fast growth rate, adding 2-3 feet to its height each season.
- Bark and Leaves: The tree has smooth bark and spreading branches. Its oval leaves are generally divided into three leaflets and have long stalks that attach the leaf blade to the stem.
- USDA Zones: It is hardy down to USDA zone 5 but is not recommended for zones that are USDA 7 and above.
- Root System: It has a shallow root system that doesn’t spread widely.
- Lifespan: Has a short-lived tree, often lasting only 10 to 20 years.
- Light Tolerance: The tree requires full sun to partial shade and does well in well-drained soil.
- Temperature and Humidity: It prefers a climate where both summer and winter temperatures are moderate. It does not do well in the heat and humidity of the deep South (south of USDA Zone 7).
- Problems: The tree can be susceptible to aphids and mealybugs. It also doesn’t tolerate heat well.
- Toxicity: All parts of the tree are extremely poisonous to humans as well as goats and horses, especially when not ripe. The harmful part of the plant is the seedpods.
- Water and Soil: It requires well-drained soil and does not do well in standing water. It is particularly susceptible to root rot.
- Propagation: It can be propagated from seed, root cutting, or stem cutting. The seeds should be started indoors at a temperature of 55 to 70 F, and they will germinate in 30-60 days.
- Flowers: The tree produces long, pendulous clusters of bright yellow flowers in late spring. These flowers are highly ornamental and have a sweet fragrance.
Golden Chain Tree Seeds
The seeds of the Golden Chain Tree are legumes with a large number of black seeds. The tree has a shallow root system that doesn’t spread widely, making it suitable for small spaces or container growing.
You can collect seeds from the tree itself after the blooming period, when the pods dry out. The seeds are contained within bean-like pods that should be harvested when they are mature.
Before planting, the seeds need to be prepared. This usually involves scarification, a process where the seed coat is damaged to allow water to enter the seed and begin the germination process. This can be done by pouring boiling water over the seeds and soaking them for 24 hours. Repeat this process for seeds that don’t imbibe. If the seed coat is still too hard, you may need to file or sand it to allow water infiltration.
Once the seeds are prepared, they can be planted. Sow the seeds 1/4″ deep in a pot filled with a well-draining potting mix. The seeds should be kept at a temperature of 55 to 70 F. You can expect the seeds to germinate in 30-60 days.
Once the seedlings have grown to twice the height of the pot, they can be transferred to a larger pot about 12 centimeters wide. When it’s late spring, move the pot outside and keep it adequately watered. When the seedling is well established, it can be transplanted into the ground. Choose a location that receives full sun in the first half of the day and partial shade in the afternoon.
Golden Chain tree problems
- Aphids: These tiny, sap-sucking insects can infest the tree, particularly young and stressed trees. They cluster on the undersides of leaves, causing them to curl, become discolored, and potentially stunt growth.
- Canker Diseases: Fungal diseases like Nectria canker can attack the tree, causing sunken areas and cracks to develop on the bark and branches. These cankers can restrict nutrient flow and weaken the tree over time.
- Powdery Mildew: This fungal disease thrives in cool, humid conditions and appears as white powdery patches on leaves and young stems. It can hinder photosynthesis and reduce the tree’s overall health.
- Leaf Spot: This is another fungal disease that can affect the Golden Chain Tree. It causes spots to appear on the leaves, which can eventually lead to leaf drop.
- Blight: Blight is a fungal disease that can affect the Golden Chain Tree, causing leaves to turn brown and fall off prematurely.
- Environmental Stress: The Golden Chain Tree prefers cool summers and mild winters. In excessively hot and dry climates, the tree can experience stress, manifesting as wilting leaves, stunted growth, and increased susceptibility to pests and diseases.
- Nutrient Deficiencies: If the tree lacks essential nutrients like nitrogen, phosphorus, or potassium, it can exhibit various symptoms. These might include stunted growth, yellowing leaves, and a decline in overall vigor.
- Root Issues: Although uncommon, poorly drained soil or planting the tree too deeply can lead to root rot caused by fungal pathogens. This can cause wilting, leaf drop, and eventually, tree death.
- Toxicity: All parts of the Golden Chain Tree are extremely poisonous to humans as well as goats and horses, especially when not ripe. The harmful part of the plant is the seedpods. This toxicity is due to the presence of cytisine, a highly toxic alkaloid.