Life on the Edge

The forest edge is a messy place. Filled with briars, shrubs, small trees, and saplings, this transition area does not have the aesthetic appeal of a cathedral forest or an expansive mountain bald. Yet the variety of life along the forest edge is remarkable and useful. Three edge plants in particular- the sourwood tree, the elderberry shrub, and the purple-flowering raspberry- represent the diversity found there and the practical value humans have found in these species over the ages.

Sweet sourwood

The sourwood tree (Oxdendrum arboreum) is widely associated with the Appalachians, from the old Appalachian fiddle tune “Sourwood Mountain,” to the familiar sourwood honey sold at roadside stands. Its core habitat in the southern and central Appalachians is obvious on the tree’s range map, although its territory extends into much of the southeast. Sourwood honey is perhaps more familiar to most people than the tree itself, and the irony of such a popular, sweet substance produced from a tree with “sour” in its name is evident (the name refers to the bitter taste of the leaves). Nectar from its small, white flowers yields a light, almost clear honey that is coveted for its smooth taste. The tree, however, has ornamental qualities that should not be overlooked. Its small to medium mature height; dense, glossy foliage; and symmetrical shape make it ideal in many landscaped settings. While individual sourwood flowers are tiny, the bell-like blooms hang in lineal groups, giving the tree a “dripping” appearance in mid- to late summer. Sourwood’s deep red foliage in the fall also adds to its appeal.

Elderberry for longevity

While elderberry (Sambucus canadensis) is a native New World shrub, a similar species of the same common name grows in Europe and is considered by some botanists to be the same species, only a different variety or subspecies (several exist worldwide). The name comes from an archaic word “aeld” meaning to kindle a fire; a reference to the fact that the stems have a distinct inner pith that is easily removed and quick to burn, leaving a hollow stem through which one can blow to stimulate a flame. Both Native Americans and Europeans have found numerous practical uses for the elderberry stem. The scientific name Sambucus is derived from the name of an Old World musical instrument called the sambuke, which was made from elderberry stems. Indians used the stems to make clapper instruments. Other uses through the ages have included pegs, arrow shafts, and blowguns.
Perhaps the most common use of elderberry today is processing the late summer fruit into jelly and wine. Other parts of the plant (including unripe fruit), however, contain a cyanide-type substance that is poisonous if ingested. Nevertheless, gardeners in the past found this substance to be useful as an insect repellent when released by crushing the leaves, and the toxicity of the leaves has been employed as a purgative, and for various external afflictions.
Recent medical and nutritional research could add a whole new meaning to the name elderberry, i.e. a berry with health benefits that enables persons to live to an elderly age. Studies have revealed anti-cancer substances in various fruits and berries, including elderberry. Elderberry, however, is not widely cultivated commercially. The agricultural obscurity of the plant may soon change, as the U.S. Department of Agriculture is currently examining the feasibility of cultivated elderberry plants. Elderberry products, such as juice and herbal supplements, are currently available in many health food stores.

Native raspberry

As with the elderberry, native raspberry species are found in both Europe and North America. The purple-flowering raspberry (Rubus odoratus) is especially prominent in the Appalachians. Its leaves are reminiscent of maple, and it tends to grow in dense thickets on the forest edge. Rubus odoratus makes an attractive tall ground cover, but the fruit is rather insignificant, with a disappointing taste. Modern garden-cultivated raspberries, incidentally, were developed by crossing European species with North American varieties. Wild European raspberries tend to have superior fruit, while the North American ones are more hardy and adaptable. Indians and European settlers found the purple-flowering raspberry to be useful for its medicinal benefits, rather than as food. A poultice made from the leaves has an astringent quality that can be applied to various skin ailments such as burns and sores.
In both human affairs and the natural world, the periphery tends to draw a more varied collection of interesting characters than the core. Frontier towns, California, & modern East Coast cities have reputations for an assortment of eccentric personalities. Examples abound in nature too, such as estuaries- where freshwater rivers blend with the salty ocean, hosting a wide variety of marine life- and atmospheric frontal boundaries, where the clash of cold and warm air often results in violent weather. Mountains are well-known for vertical diversity of species due to varying elevation. A horizontal diversity of species can be found as well at the forest edge. Though often unattractively weedy and brushy when viewed collectively, individual species such as sourwood, elderberry, and purple-flowering raspberry make the forest edge an interesting environment.