When you think about the intelligent, courageous and, inevitably, flawed people who founded our country, a host of names come to mind. Bernard McMahon’s is not among them. However, McMahon—1775-1816—knew or corresponded with many of the political and horticultural notables of his era. He was a garden mentor to Thomas Jefferson, who may be considered America’s “founding gardener.” That association also led the third president to choose McMahon as curator of the plants collected by Lewis and Clark on their lengthy and daring western expedition.
McMahon, an Irish immigrant, was a nurseryman, plant collector and writer. His American Gardener’s Calendar was the first book of guidance aimed at gardeners in our newborn country. He sent American native seeds and specimens to correspondents in Europe and offered European horticultural delights to customers in America. And though early American gardening was necessarily derivative of European gardening, McMahon encouraged his readers to look close to home for worthy plants. Peter Hatch, writing in the January 1993 edition of Twinleaf, the journal of the Jefferson Center for Historic Plants, noted, “It was in the Calendar that American gardeners were first urged to comb the local woodlands and fields for ‘the various beautiful ornaments with which nature has so profusely decorated them’.”
It is no wonder, then, that botanist Thomas Nuttall, McMahon’s contemporary, named a new genus, Mahonia, after Bernard McMahon.
I wish more people would grow Mahonia and not just because McMahon should be honored and celebrated in his adopted country.
Every garden needs structure and evergreen shrubs are a great way of marking boundaries, defining specific areas and providing year-round color. The most common varieties of evergreen Mahonia, sometimes called “Oregon grape holly” do all of that and more. The “Oregon” common name usually refers to an American native species, Mahonia aquifolium, which is native to the West. Sometimes it is also used to describe Mahonia japonica, a native of China, with similar good looks and habits.
If you saw a single Mahonia aquifolium or japonica leaflet—dark, glossy green, with spiny edges—you would think it was a holly leaf. The resemblance does not go much further, as Mahonias and hollies are not closely related. Both genera bear leaves that are alternate on the stems. Mahonia differs from holly in that each “leaf” is really a compound structure up to one foot long, made up of anywhere from seven to 19 leaflets that are also opposed on the stems. Botanists refer to this form is called “pinnately compound”.
True holly leaves start out green and stay that way. Mahonia leaves emerge red and green up as they mature. Holly’s wood is light brown when cut, whereas Mahonia wood is bright yellow, like its relatives, the barberries.
Another very visible difference between true hollies and Oregon grape holly is the flowers. Holly flowers are most often small and white, giving way eventually to the bright red berries that adorn our holiday decorations. Mahonias bear showy panicles or flowerheads of small yellow blooms with a pronounced lily-of-the-valley scent. The bees love them in spring and so do humans.
Once the flowers have faded, the blue “grapes” of Mahonia’s common name appear. These are round to oval, blueberry-size fruits with a waxy or glaucous surface. Though sour, they are edible and can be made into jam if you are so inclined and can get to the bushes ahead of the birds.
Shade gardeners frequently despair about their landscape choices. They can rejoice in Mahonia, which thrives in partial shade. Once established in neutral to acid soil, it can also survive drought. Many true hollies grow into substantial trees; aquifolium and japonica grape hollies top out at three to seven feet. For those with smaller spaces, the ‘Compacta’ variety of Mahonia aquifolium reaches only three feet tall.
Mahonias suit woodland-type gardens, evergreen showcases and habitat landscapes. The aquifolium species is perfect for native plant gardens. I would choose Mahonia over barberry every time for boundary hedges. Like barberry, Mahonia increase by producing root suckers, but if you watch out for them and remove them promptly, the plant will not spread. If any pruning is necessary, do it after the flowers have faded.
Throughout America’s history, people have applied their own definitions to the word “patriotism” and those definitions sometimes cause conflict. If you want to define non-controversial patriotism—and good horticultural judgment–in your own garden, plant Mahonia aquifolium and honor Bernard McMahon.