It is hard to miss Hong Kong’s flame tree, especially during its flowering season. Weeks after they began to bloom, the scarlet red flowers remain, casting vivid strokes of colour across the city. Look up and you will see large red petals on spreading branches; look down and you’ll notice how the fallen flowers form a red carpet on the floor.
The flame trees are blooming with extra intensity this year. Perhaps it is due to the early heat wave, dry spring or less stormy spring weather; whatever the case, the spectacular red flowers are catching more attention than usual. Delonix regia is the Greek name of the tree, which is known as the Phoenix tree in Chinese (fung6 wong4 muk6 凤凰木). Much beloved for its flamboyant flowers, the species was introduced to Hong Kong in the early 1900s, from Madagascar’s deciduous forest to this densely populated and already urbanised British colony. Perhaps when this Phoenix tree was first planted in Hong Kong, the city still had some resemblance to its original habitat – subtropical weather, abundant water and lots of space for the tree to expand. Nowadays, this wild flame must contend with the one of the world’s most dense and vertical urban environments.
Despite these challenges, the tree remains popular in Hong Kong. Dr. Allen Zhang, assistant professor at the Faculty of Design and Environment at the Technological and Higher Educational Institute of Hong Kong (THEi), says Delonix regia is planted by various landscape management companies everywhere from Hong Kong Island to Kowloon, the New Territories and the outlying islands. “The flame tree could adapt to Hong Kong’s environment very well in urban parks, public housing estates, and public spaces, but not as a roadside tree,” says Zhang. “Limited space results in oxygen deficiency, malnutrition and conflict with pavement.”
That’s because Delonix regia grows horizontally rather than vertically. Usually, its canopy hovers about five metres above the ground. The average mature spread extends beyond 15 metres, casting large shadows that are perfect for tropical and subtropical environments. Its buttress roots also spread, reaching them to plunge deep into the earth in order to secure the tree’s voluminous canopy. By nature, Delonix Regia requires a lot of horizontal space to mature – exactly what urban Hong Kong lacks. “Planting a Delonix regia in the urban area is like taking a giraffe out for a walk on Des Voeux Road,” says Gavin Coates, a senior lecturer at Hong Kong University’s Landscape Architecture Division, who worked as a landscape consultant for the city’s Greening Master Plan, which has planted more than 20,000 urban trees since 2004.
While this year’s bloom seemed to last for weeks, the spring’s fickle weather normally takes its toll on the Phoenix tree’s remarkable colours. Unpredictable weather makes maintaining such trees a nightmare. Their large flowers are easily swept out of the branches, which requires street sweepers to put in additional hours of work. More problematic is the tree’s tendency to be infected by Brown Root Rot, a plant cancer. A seemingly sturdy trunk may be entirely rotten from within. Without careful maintenance and regular examination, this flame tree may fall over and cause fatal accidents. One Delonix regia was registered on Hong Kong’s Old and Valuable Tree list, which documents particularly old, important or otherwise remarkable trees. Unfortunately, it was infected by Brown Root Rot and chopped down in 2013.
As a result, the government no longer supports planting this beloved tree in crowded urban areas, but the gorgeous flame trees are still widely planted in less densely populated parts of Hong Kong – and there are plenty of specimens that remain in central locations like Victoria Park and the South side of the island.
Despite its challenges, landscape architects are not giving up on this brilliant specimen, even in Hong Kong’s urban area. Zhang says that with sufficient space, careful maintenance, and regular examination, the flame tree has a lot to give back to the city, both ecologically and aesthetically. The tree provides much needed shade to the urban environment – and who can resist the allure of its spectacular spring awakening?