When the dark days of winter set in, Mahonia gives a blast of sunshine in an otherwise drab garden. The type species Mahonia aquifolium above is named after Bernard McMahon, a horticulturalist who was born in Ireland (circa 1775) and settled in Philadelphia in the United States. He is best-known for his work The American Gardener’s Calendar. His namesake plant works hard at those times in the gardening calendar when winter colour is hard to find.
There are around 70 evergreen species in the genus. Mahonia belongs in the Berberidaceae or Barberry family. Not all botanists agree on the current classifications. According to Christenhusz, Fay and Chase in Kew’s Plants of the World (2017), the distinction between the 2 genera Berberis and Mahonia is vague. Mahonia is currently included within Berberis in the Berberidoideae subfamily.
Colourful Flowers and Fruits
The evergreen leaves resemble holly leaves and can change colour as they age and/or in response to cold weather. The berries can put on a show too, further emphasising the original inflorescence structures: long terminal clusters or spreading racemes.
Oregon Grape is somewhat untidier than other Mahonia species. It also has the unfortunate tendency to produce suckers. A dwarf or standard species like Mahonia media Winter Sun may be more suitable for your garden.
Mahonia has a long history of medicinal use, especially in Chinese medicine. According to Jian-Ming He and Qing Mu (2015) in Volume 175 of the Journal of Ethnopharmacology, it has the following applications:
Chinese medicine considers that most Mahonia species relieve internal heat, eliminate dampness, remove toxins, suppress pain, promote blood circulation, inhibit coughs and alleviate inflammation.
Mahonia contains berberine. It is commonly taken orally as a treatment for diabetes, high cholesterol and high blood pressure in Western medicine. It is sometimes used to treat burns and sores as well. It has a host of other applications, although research is ongoing. Usage is not suitable for everyone without medical advice and supervision.
Dispelling the Myth
There is a myth that you must grow native plants in your garden for wildlife. While it is undoubtedly desirable to have native plants, relatively little is in flower to supply nectar in December. The local wild flower specimens were very scrawny and few on the ground today. It was a sunny day. The reported high temperature was 9ºC, although it felt slightly warmer in the sun. Three to four Bumblebees were feasting on Mahonia inflorescences.
According to the Bumblebee Conservation Trust, the hardy Buff-tailed Bumblebee (Bombus terrestris) is still active at this time of year, while other bumblebees are in hibernation. Mahonia is one of their favoured plant species.
Two animations of active Bumblebees on local Mahonia inflorescences appear below:
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