Scientific Name: Dichroa febrifuga
Common Names: blue evergreen hydrangea; Chinese quinine
Plant Type: Perennial evergreen shrub; grows to 3-7ft
Environment: Light shade/part sun with regular watering. Hardy to about 20-25°F
Bloom: Spring through Summer
Uses: Good garden accent. Fruit attract birds. Medicinal.
Other: Similar to the blue forms of Hydrangea, the blue shade of the flowers is determined by soil pH (or more precisely, the availability of aluminum). More acid soils produce bluer flowers.
Native to the rich, mixed forests within a broad range of Southern Asia, from China to Tibet, India, Myanmar, Laos, Thailand, Vietnam, Cambodia, and to the islands of the Philippines and Java, this colorful accent is also a common resident of several themed areas within our Garden.
A close relative of Hydrangea, Dichroa offers a similar shrubby habit to seven feet tall and 5 feet wide with a subtle, yet colorful cluster of flowers at the tip of the stems, each individual a botanically “perfect flower” with pink, purple, or blue petals. Flowering season is quite long for blue evergreen hydrangeas and occurs late spring through summer, followed by a small, candy-blue to purple berry that extends the ornamental nature of the specimen through the fall season. Dichroa prefers part sun to light shade and moist, well-drained soil. If mulched to retain soil moisture, watering may be reduced to once or twice weekly. As with other hydrangeas, flower color can vary depending on both soil acidity and soil aluminum concentration. At low pH (pH<7.0, acid range), aluminum in the soil is in a more soluble form, that is, a form that is much more available to be taken up with water by the plant’s root system. At high pH (pH>7, alkaline/basic range), aluminum is in a form that is much less available for root uptake, as it forms insoluble compounds that cannot readily be absorbed by the root system. Acid soil with a higher concentration of available aluminum will produce deep blue flowers, while soils with a higher pH and lower concentration of available aluminum can range from purple to pink.
Published as one of the 50 most fundamental herbs in traditional Chinese medicine, it is reported that the root of Dichroa febrifuga has been used for as many as 2000 years to treat malaria. As recently as 2012, a scientific publication in the international journal Nature reported on the activity of the chemical compound febrifugine, derived from this species. Not only is there support for understanding the method by which this compound treats malaria, but febrifugine is also being studied for potentially related therapeutic uses to treat cancer and fibrosis. It has also traditionally been used to lower blood pressure, relieve chest congestion, and to endow resistance to tumors, flu, and intestinal bacterial infections. The species name, febrifuga, is derived from the Latin febris, or fever, and fugare, to drive away.
How is it that this unassuming, common plant can play such an important role in human health – past, present, and perhaps future? Other examples in the plant kingdom are all around us and not as uncommon as we may think. Among other important uses by humans, plants have been our medicine cabinet for millennia. Regardless of cause, when a species disappears from the planet we have the potential to lose much more than just a pretty flower.
IN BLOOM CONTRIBUTORS: Text by Corey Barnes. Photos by Mona Bourell and Joanne Taylor.