There is an invasion of leatherleaf mahonias on the Inner Harbour campus forest where I work, and it is alarming. It all started when some were planted in landscaping for the lodge. They appeared to be an odd variety of holly, and though someone liked them enough to plant them there, to me they were like an off note in a chord- they did not fit in the natural environment. For several years, these plants have grown slowly and spread greatly. When birds spread the plants’ seeds through droppings, plants appeared in profusion in the immediate area (41 by my count), and they also appeared in isolated spots as far as a mile or more away. The spread was similar to what one would expect of privet. Invasives such as the leatherleaf mahonia can be beautiful, have 
interesting features, and be beneficial in many ways, but they should only be grown where they can be responsibly contained.
The leatherleaf mahonia is a member of the barberry family, Berberidaceae. It was introduced to America from China in 1848 as an ornamental. Known as Beale’s barberry, its scientific name is Mahonia bealei. The largest specimen I have seen measured 6.5ft., across the street from Kennestone Hospital in Marietta, GA. (see last picture). Most sources state that 
leatherleaf mahonia is a shrub that only grows 8 to 10 ft. high, but Flora of China, vol. 19, page 773 states that this plant’s height can reach 26 ft., which is the size of a small tree. After observing this plant’s aggressive nature and coarse form, I am convinced that it can grow to tree size under the right conditions. Preferring dappled sun, it does not like deep shade and it can get burned in too much sun. Once established, the leatherleaf mahonia is drought resistant. It can be found in well-drained forests and forest margins, on weedy slopes, and along streams and roadsides. There is no mistaking the irregular, vase-shaped form of leatherleaf mahonia.
While the leatherleaf mahonia is growing at a 
very slow rate, its shallow, suckering root system with basal sprouts is trying to colonize thickets. Seedlings are light green or purple, and develop thin, tan to gray, fissured bark. Stems are upright and stiff, with irregular branching. If a more dense shrub is desired, the tallest stems may be pruned back in early spring to encourage new growth at the base.
Leaflets of leatherleaf mahonia look much like the spiny leaves of holly, but there are important differences. While holly leaves alternate on stems, a leatherleaf mahonia leaf has 4 to 10 pairs of leaflets, plus a larger terminal leaflet, along a rachis. The rachis occurs alternate on strong, upright stems, 
and it can measure 20 inches. The leaflets increase in length and decrease in width from base to apex. Leaflets are thick and rigid, with up to 7 spines on each leaflet. They are leathery, stiff and prickly, with dark green to blue-green color. Leaf color below is a lighter yellow-green. Lush new foliage emerges rapidly after flowering in winter.
Fruit are formed on the leatherleaf mahonia from small, fragrant, bright yellow flowers that bloom, clustered, on 3 to 6-inch spires, or racemes. Flowers have both male and female parts, and are pollinated by insects in January and February. Oval, fleshy-skinned fruit containing 2 to 3 seeds grow to be .4- to .7-inch long. Color of fruit begins light yellow to green, as shown in this picture taken late January. In spring, fruit turns robin’s egg blue, and ends purplish black with a powdery sheen when ripe in summer. The picture below was made March 24, and birds have already picked over the fruit. Because this fruit and all Mahonia fruit varieties appear somewhat like grape clusters, many Mahonia varieties, such as the native Oregon Grape Holly, have the word grape in their common name.
Uses for the leatherleaf mahonia are varied. As a specimen, it has a unique, coarse overall appearance unlike anything else in the area. The plant blooms colorful bright yellow flowers in winter when little else blooms, and has berries for color later into spring and summer. Bees enjoy the flowers when little else is available. Because it has spiny leaves that are unpleasant to brush up against, several can be planted strategically to make a dense and effective security hedge or a natural security barrier under windows. The plant could be a great border or background shrub. The fruit is edible, but tastes very sour and acrid when eaten raw. It is used as a flavoring in porridge, muesli, and other dishes, and it can be made into jellies. Like other plants in the 
Barberry family, the leatherleaf mahonia contains berberine which has antibacterial medical effects. A decoction of leaves, roots and stems has been used as a tonic and to treat such ailments as dysentery, weak knees, backache, rheumatoid arthritis, TB, recurring fever, inflammation of the intestine, and more. Perhaps research will uncover important products from this plant that we can reliably use. Always be cautious and well informed before trying any plant as reaction, dosage and other factors are serious concerns.
Though it would be great to have the leatherleaf mahonia shrub or small tree for any of the reasons given in this article, it would be very hard to contain 
its invasive nature. Perhaps the cement and asphalt environment of city landscapes would most easily contain this plant. I have observed the countryside spread of this plant, and it is quicker than most would imagine. Seeds are spread very easily by animals, by water, and in other unforeseen ways. The leatherleaf mahonia is now on the invasives list for Mississippi, Alabama, Georgia, Tennessee, and South Carolina. A good article about this, with pictures, is https://articles.extension.org/pages/62638/mahonia-bealei-leatherleaf-mahonia. For whatever reasons the leatherleaf mahonia may be desired, it should be grown only if it can be responsibly contained.
