Oregon Grape

Oregon Grape,
aka Mahonia,
aka Mountain Grape,
aka Grape Holly,
aka Tall Oregon Grape,
aka Hollyleaf Barberry

   

Although the leaves look just like English Holly, Oregon Grape (Mahonia aquifolium) is really a barberry shrub. It grows seven to ten feet in height, & can be three to five feet wide. To limit its width, suckers can be removed as they appear, encouraging only the upward branches, creating very narrow upright specimens. If the species seems a bit big, there are smaller cultivars including "Compacta" & "Mayhan Strain" that are three by three feet or smaller. "Apollo" is a true dwarf that flowers heavily & makes an excellent evergreen groundcover under trees.

The dwarfs I'm fairly certain are always hybridized with the ground-creeping M. repens, either crossed in cultivation or even occurring naturally in the wild. A pure wild M. aquifolium is a very erect shrub, whereas specimens that grew from casual pollinization with M. repens will be more varied in form, being shorter, wider, clumpier, but only occasionally completely prostrate.

We have two specimens of M. aquifolium one planted under large evergreens in considerable shade, the other under the Paperbark Maple where it gets indirect sunlight at least. The above photo was snapped the day we brought one home & just before we planted it under the Paperbark Maple (it was not planted in front of that Camellia japonica the leaves of which can be seen behind it in the photo). It's a June photo so it's full of green berries that will not ripen until Autumn. I remember the day we bought this shrub, there were some very densely foliaged specimens we might have chosen instead, & the nurseryman seemed surprised we wanted this thin one, but after looking at scores of them offered by various nurseries, this was the first one that said "Take me home!" We later added the bushier one farther along the cliff edge, because to fruit well, they need to be able to crosspollinate with other mahonias.

We've also two specimens of M. repens in shady dry ground not far distant from the aquifoliums, both a little farther down the tiny cliff. Their conditions are a bit harsh because a large holly tree & a fir tree suck the ground dry, & the shade is so deep even weeds don't much grow on that slope. But if anythiung, the M .repens are doing even better, as they bloom first & better. All the four shrubs of the two species are doing just fine, though, whereas if they'd been in a sunny & well-watered location, they probably wouldn't do as well.

Mahonias only fruit if they can pollinate with nearby specimens of its own species, or with a compatible species, & these two species do cross-pollinate at will.

Oregon Grape is the state flower of Oregon. M. aquifolium is native of the Pacific Northwest from northern California through Oregon, Washington & British Columbia. The genus name honors Irish-American pioneer nurseryman Bernard McMahon (1775-1816), a pal of Thomas Jefferson who was a radical gardener for much longer than he was a president, & whose gardens persisting at Montecello to this day include much that was provided to Jefferson by McMahon.

The Philadelphia nurseryman became curator over the seeds & plants gathered in the west during the Lewis & Clark Expedition, & he was the author of the horiticultural classic The American Gardener's Calendar (1806). Botanist Thomas Nuttall named the western group of shrubs mahonias in remembrance of McMahon within two years of the death of America's first national nurseryman.

In the garden Oregon Grape is not at all fussy as to soil conditions. It grows in most any lighting condition from deep shade to full sun, though it definitely likes partial shade or dappled sunlight best. It gets redder in winter with more sun exposure, but has a better overall appearance year-round when provided with a bit of shade. With too much winter sunlight it will get spotty, ruining its bronzy coloration; ours being in deeper shade, they never get the winter spottiness, but instead have a bronzy winter cast to the green leaves that lasts until spring.

A first-rate hedgerow can be made from mahonia, for areas too shady to grow other hedgeable shrubs. It can be cultivated from seeds sewn winter or spring, or by digging up suckers & babying them in pots for a while. They'll also reproduce from autumn leaf-cuttings.

The fragrant flowers appear as early as January & last through May. In the most southerly part of its range into California, where it experiences fairly warm winters, it will bloom beginning in December. These flowers are edible & can be used raw in salads, or fried in tempura. The flowers can also be boiled to make a lemonade substitute.

Spring's yellow blooms have turned into green berries by June. The berries darken to a beautiful dusty or frosted blue beginning in July, but will not really be ripe until autumn, when the blue-black berries on red stems amidst bronzy leaves place this lovely shrub at the height of its ornamental powers.

The fruit occurs in bunches & really do look like small grapes, the size of large black currants. They are quite tasty right off the bush despite being seedy & acidic. Cooked, sieved, & sweetened for jams is best. As with most acidic autumn berries, if they are harvested in winter after they have gone through a couple of frosts, they taste much better, as the cold breaks down the pectins & increases the percentage of fructose. All mahonia species have edible berries, but M. aquifolium is one of the best, & is the most heavily productive.

Unfortunately for us, the birds very much agree the grapes are tasty. We have many autumn & winter berries that the birds only eat sporadically because most cold-season berries are simply too tart to be a first choice of meal. But for the mahonia, as soon as a short cold spell sweetens them a bit, the birds get them all. One day the bush is full of berries, the next it has none! Wherever this is predictably going to happen, they can be picked the instant they turn black, & "frosted off" artificially in the freezer.

The First Peoples of Oregon, Washington & British Columbia made a bitter tea from the root as a general tonic to treat weariness, loss of apetite, venereal infections, digestive problems, or gargled for soar throat & bronchial infections. The fruit was used as a mild laxative. And a yellow dye was made from a substance taken from the underside of the bark, violet dye from the berries, & green dye from the leaves.

As a medicinal plant, Oregon Grape extract has been shown to be useful in treatment of skin disorders such as soriasis & fungal infection. Acting on reports of a Vancouver Island Salishan woman who successfully treated dermatitis with bark of the Oregon Grape, a 1992 dermatological study was conducted in Germany to assess the value of this folk-remedy & its known active ingredients, berbamine, oxycanthine, & berberine. The outcome of the study became notoriously exaggerated when filtered through the wild promises of herbal remedy manufacturers, but even so, the medical value of mahonia is worth taking seriously.

   



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