Recognizing the Hong Kong Orchid Tree
January 16, 2024
By Karen M. Maxwell, Horticultural Specialist & Horticulture Programs Coordinator
The Hong Kong Orchid tree is among many people’s favorite winter blooming trees here in Southwest Florida, and it has become the generic name attributed to several species of Bauhinias, but there are some substantial differences. If you wish to plant a ‘poor man’s orchid’ tree in your yard, be sure to understand what sets various Bauhinia species apart, lest you get mad at me thinking I recommended that messy, invasive tree for your garden!
Most gardeners can recognize a Bauhinia species by its unique leaf shape – as one of my dear former co-workers recently pointed out, “you mean the butt tree.” The round leaves are cleft at the end making it appear lobed and the genus epithet is attributed to two brothers, Swiss botanists Johann and Casper Bauhinia. All 300+ species of Bauhinias (boh-HIN-ee-uhs) are native to the Eastern Hemisphere and many species have found our Zones 10-11 much to their liking.
A Hong Kong Orchid Tree is a naturally hybridized cross of Bauhinia variegata (Orchid Tree) and Bauhinia purpurea (Indian Purple Orchid Tree) and after it was accidently discovered in China, it was introduced to Hong Kong and celebrated by naming it after the wife of then Governor Blake of Hong Kong. Until the discovery of Bauhinia x blakeana (remember ‘x’ means hybrid), Buddhists believed the original Orchid Tree was sacred and they planted it extensively next to shrines and holy temples.
Don’t let sorting out these bauhinias give you a headache. A few identification keys will help provide easy recognition. Both the Hong Kong Orchid and one of its parents, the Orchid Tree, always retain their leaves at the same time they are blooming; additionally, the Orchid Tree blooms in Autumn, well before the Hong Kong Orchid which is blooming now (in winter).
Similarly, the Hong Kong Orchid and Orchid Tree produce striking five-petal pink flowers, each with five prominent stamens and each are prized for their fragrance. The most important key difference is that immediately after blooming, the Orchid Tree (B. variegata) is distinctively identified with its prolific seed pods (and no leaves). They quickly dry out and twist like corkscrews forcing the pod to burst and toss seeds far and wide – and with a high germination rate, they earn their reputation as an invasive plant here in our Zone 10. Most reputable nurseries will not sell the Orchid Tree (B. variegata) in our area but if you want to be sure, just look at the flower.
The B. variegata produces a superior petal, where one of five petals is dominantly larger than the others (similar to the Royal Poinciana flower). This is a method of attracting birds and other suitable pollinators by providing a marked highway to locate its nectar. In defense of this invasive tree, it does possess many ethnobotanical qualities used extensively in other parts of our world – particularly in medicine and in cuisine. The leaves, flower buds, and young seed pods are cooked as vegetables and often used in Indian cuisine. The edible flowers will provide an elegant touch atop salads. The next time you want to impress your guests, instead of an orchid or nasturtium flower, throw a Bauhinia flower on their greens.
Bauhinia variegata ‘Candida’ is a white variety of the Orchid Tree and it too produces seed pods; however, as with many plants with a white cultivar, they do not flower as profusely, and it follows that fewer seed pods develop as well. To recognize this cultivar, look for a white flower with green veins on the backside. This tree is currently growing between our Japanese Garden and the Caretaker Cottage.
On the other hand, the Hong Kong Orchid tree (Bauhinia x blakeana) is a sterile tree, producing no fruit or seeds, making it the prize of the Bauhinia genus. Reproduction of this tree is solely by vegetative cuttings or air layering and, it is said that all Hong Kong Orchid trees originate from the tree introduced to the Hong Kong Botanic Gardens where it was planted in 1908. In 1965, it was named the official tree of Hong Kong. Dr. David Fairchild brought it to the United States in 1925.
All of the above species of Bauhinias can grow into trees as tall as 40 feet, with random branching, crisscrossing back and forth but if pruned immediately after flowering, these Bauhinias can be easily maintained to a suitable size or shape. If you have an Orchid Tree (B. variegata), or any of the seeding varieties, this is also the time to remove the long pods.
Most Bauhinia species do very well on alkaline soils, particularly in areas with limestone. They are very intolerant of salt and they can also show signs of potassium deficiency that a balanced, quarterly feeding will prevent. Bauhinias are heat loving and fairly drought tolerant once established, but if they do not receive adequate water, the leaves will begin to brown at the edges, so during long hot, dry periods, provide additional water. These trees are true tropicals and will not survive freezing temperatures.
The Bauhinia collection at the Estates also includes Bauhinia tormentosa, a native to India, with the common name of St. Thomas Tree – it produces yellow flowers. The smaller, shrub-like Bauhinia monandra or Napoleon’s Plume, has beautiful clusters of pink flowers and is found in the Bulb Garden. A stunning red flowering Bauhinia located in the croton garden behind the main gate, the Red Orchid Tree or B. galpinii is native to South Africa and blooms throughout our summers and maintains a manageable size under 15 feet and is a spectacular specimen in bloom. A vining variety, the Climbing Bauhinia (Bauhinia corymbose), produces lavender flowers and is hardy to about 20 degrees. This evergreen bauhinia is a butterfly favorite, so look for this one in the butterfly garden near the Garden Shoppe.
Whichever Bauhinia you choose for your garden, they will always have the same shaped leaf and when they bloom, the flowers will be outstanding! To learn more about gardening in Florida, sign up for the Introduction to Florida Gardening classes. Register early because they fill up quickly!
BOLO (Be On The Lookout)
IN THE GARDEN:
The Golden Shower Tree (Cassia fistula) should begin its showstopping blooms soon.