Dichroa febrifuga

Few garden shrubs carry a resume like Dichroa febrifuga. In the ground this is a handsome, medium evergreen with lacecap heads of small blue flowers in late spring and, better still, clusters of berries in fall that ripen to an almost unreal iridescent, metallic blue, the kind of structural color usually reserved for beetles and tropical birds. A relatively recent introduction from China, the plant sits close enough to Hydrangea, in the family Hydrangeaceae, that the same trick applies: acidic soil deepens the flowers and fruit to true blue, while alkaline ground pushes them toward pink.

Both halves of the botanical name reward a moment of attention. Dichroa comes from the Greek for two-colored, a nod to those shifting blues and pinks, while the epithet febrifuga is plain Latin for fever-dispelling, and that second word opens onto two thousand years of history. In China the plant is chang shan, named for Mount Chang, and ranks among the fifty fundamental herbs of traditional medicine. The roots appear in the Shennong Bencao Jing, the oldest surviving Chinese materia medica, and again in Zhang Zhongjing's Han-dynasty Treatise on Cold Damage, prescribed above all against the recurring fevers of malaria.

The modern chapter is just as remarkable. In the twentieth century, chemists chasing the herb's power isolated the alkaloids febrifugine and isofebrifugine, and those molecules in turn inspired a synthetic derivative, halofuginone, that has since traveled far from the fever clinic, serving as an anticoccidial in poultry feed and as a research compound studied for fibrosis, cancer, and autoimmune disease. The tradition came with a hard catch that modern study confirmed, since chang shan is strongly emetic and toxic to the liver in more than small amounts, which is exactly why the plant belongs in the garden as an ornamental while the pharmacology belongs in the laboratory. Nothing here is medical advice.

Set against that heritage, the garden role is refreshingly simple. Grow Dichroa febrifuga as a lush, shade-loving shrub for a woodland border, a shaded courtyard, or a mixed planting where the metallic fall berries can be admired at close range, and keep the soil acidic for the deepest blue. The plant is handsome with hydrangeas, ferns, hostas, and aucuba, takes happily to a large container that can shelter under cover at the cold edge of the range, and asks only for moist, well-drained soil in morning sun or dappled shade.

Photo courtesy of Cambridge Botanic Garden.