Why Should You Plant Native Plants?
One of the most beautiful North American trees, the Paper Bark Birch, has long been a favorite ornamental tree for many people who live in all parts of the United States. Its natural range is the cool and often mountainous regions to the north, but it has nevertheless been planted well into the southern parts of the country. Shallow rooted, it is often constantly stressed by heat and drought in these warmer areas. The young trees grow fairly well for a few years—perhaps a dozen or so—but just about the time they reach their most beautiful and impressive size, the leaves at the top begin to turn yellow and wilt and then the twigs and branches die back progressively down the tree. The bronze birch borers have found the tree and are burrowing channels under the bark, killing the twigs and branches and ultimately killing the tree. This pest is found throughout the range of these trees, but a healthy tree can actually stop the growth of the borers by growing calluses where they have been damaged. Not so the stressed tree living outside its natural range.
The River Birch, however, including its popular cultivar ‘Heritage’, has a more southern natural range and is not so stressed by the heat, and it is resistant to attacks from the bronze birch borer. This is a perfect example of why it’s important to consider natives—and even more, “local” natives—when you are selecting plant material for your garden. A stressed tree or shrub does not protect itself, cannot heal itself as well, and actually produces a different set of chemicals which often attract pests. When you are planning your garden, or buying a plant to add to your outdoor space, consider where the plant is originally from, and whether you will be bringing an unhappy “stranger” into your local environment.
Consider, too, the native wildlife that will be passing through your yard, whose very existence may depend on what plants you are growing there. Butterflies especially need plants which they have evolved to depend on for food or shelter, and may be extremely dependent on a certain combination of locally native plants. The Monarch butterfly, for example, chooses either the milkweed plant, which is gradually being eradicated as a weed from its native open fields, or its ornamental relative, the native butterfly weed (asclepias tuberosa) which is now available from plant nurseries as an ornamental perennial plant, as a larval food host.
In fact, if you look at any published list of larval food hosts for butterflies, you will quickly become aware that they are almost all native plants, whether they are trees, shrubs or perennial plants (you may also find a few plants which are not native but are in the same plant family as a similar native, such as some fruit trees). The adults are certainly attracted to many non-native plants for nectar (think butterfly bush) but the female lays her eggs on a plant which she “knows” that her offspring, when they are in larval form and have chewing mouth parts, must eat.
Native plants supply food and shelter for many of our birds as well. Many of our non-migratory birds depend on the seeds and berries of perennials or shrubs. A listing of ornamental plants which hold their berries well into the later fall and winter (such as penstemon, coneflower, bayberry, beautyberry, and some viburnums) consists of many native plants. Admittedly, our birds will eat whatever seeds or berries taste good, so they care little whether a plant is native or not. But if you look at the balance of health for the plants and the welfare of our native beneficial wildlife, it seems that planting a native plant can benefit us all.
Kathy Noble, Landscape Designer
