Singing mountain holly’s praise

My interest in mountain holly (Nemopanthus mucronatus) as a native plant for managed landscapes was piqued by the words of Thoreau: “Wild holly, the imp-eyed, red, velvety-looking berry of the swamps … is the most beautiful of our berries, hanging by slender threads from its light and open bushes amid its delicate leaves.” Writing over a century and a half ago, his admiration for mountain holly was derived from encounters with the shrub in the swamps and bogs surrounding Concord, Mass.

While still rare in our managed landscapes, mountain holly is not new to horticulture. In his “Ornamental American Shrubs” (1942), William R. Van Dersal echoed Thoreau’s admiration: “The foliage is handsome and a specimen heavy with fruit is a beautiful sight.” And Europeans have long deemed mountain holly to be a garden-worthy shrub.

Crimson berries clustered amid blue-green foliage are the striking early-September ornament of mountain holly, but there are subtler features to enjoy, including the purple of petioles and young stems and the thread-like pedicels, often over an inch in length, that support the pendulous berries. This latter feature is described by the genus name, derived from the Greek nema, thread, and anthos, flower. The specific epithet, mucronatus, refers to the tiny bristle at the tip of the elliptic leaf.

N. mucronatus is in the holly family (Aquifoliaceae) and, like true hollies, produces male and female flowers on separate plants. At least one male should be planted as a pollen source to ensure fruit production. Mountain holly flowers are inconspicuous, not an ornamental feature of the species.

Mountain holly can be found growing in damp woods, thickets, swamps and bogs from Nova Scotia to Ontario and Wisconsin and south through New England to Virginia. In the shady tamarack woods that surround the peat bogs of Maine it grows as a tall multi-stemmed shrub with widely spaced branches and deep blue-green leaves. Here it keeps company with winterberry (Ilex verticillata), lambkill kalmia (Kalmia angustifolia), bog kalmia (K. polifolia), labradortea (Rhododendron groenlandicum) and leatherleaf (Chamaedaphne calyculata). On the edges of the open bog, where nutrients are more limiting and light is stronger, you find colonies of shorter, more compact plants with yellow-green foliage.

I was surprised to find mountain holly growing atop Cadillac Mountain, where its stunted growth testifies to the thin soils and desiccating winds of that environment. But it flourishes there in colonies that look totally different from those of swamp and bog, an indication of its tolerance for a wide range of site conditions.

In our gardens, mountain holly grows best in shade, at least partial shade, and in an acid, moist soil. For example, I have seen cultivated mountain holly thriving in the cool shade of native birch (Betula papyrifera), moose maple (Acer pensylvanicum) and hemlock (Tsuga canadensis).

Unlike the berries of winterberry, which persist through the winter, the fruits of mountain holly are taken by migrating birds that pass through our area in late August and early September. One evening you are admiring the glowing red berries, the next day they are all gone, leaving you with the sense of loss, but also the knowledge that your garden has helped sustain the birds on their long southward journeys.

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