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Native Plants
Questions and Answers
What is a native plant?
The federal Plant Conservation Alliance defines a native plant species as one that occurs naturally in a particular region, ecosystem, and/or habitat without direct or indirect human intervention. A plant endemic to Europe and introduced to North America is not native to this continent. Likewise, a plant native to one region of North America is not native to another region unless it originated there without help from us.
Purple loosestrife, of Eurasian origin, is displacing native wetland plants across much of North America.
Ecologically speaking, political boundaries such as national or state lines have no bearing on plant distribution. Plant ecologists have divided North America into 15 plant provinces (see Plant Provinces in North America map). The species in these distinct vegetation regions are determined by such regional factors as high and low temperatures in summer and winter, total annual precipitation, timing and nature of precipitation, elevation, and soil type.
What is local provenance, and why is it important?
Provenance refers to the specific place from which a plant or seed originated. Plants of local provenance—those whose native origin is close to where they will be planted—are apt to be better adapted, and therefore perform better, than plants of more distant origin because temperature, precipitation, and other factors vary within each plant province.
Growing plants that are not of local provenance can also affect the gene pool of a native species. The genetic makeup, or genotype, of a plant may vary from place to place. When a nonlocal genotype is planted, it can mix with the local plants and alter the local gene pool in a way that decreases the plant's ability to survive in the area.
Fireweed is a long-blooming native named for its tendency to colonize burned and disturbed sites.
Can a cultivar of a native plant be considered native?
Technically, a cultivar is a plant that has been selected for cultivation because of a particular attribute or group of attributes—a particular flower color, say. To ensure that these characteristics are retained, cultivars typically are propagated by cloning via rooted cuttings. A cultivar produced by cloning a wild plant may be described as native, but it is not necessarily of local provenance. So, whenever possible, avoid selecting cultivars of native species, unless they have been propagated from local plant stock. What's more, look for local genotypes produced from seed rather than by cloning, because they maintain the maximum genetic diversity.
Can native plants be invasive?
Yes, but they rarely are. Some species display invasive growth tendencies in their native regions in response to disturbances caused by us—for example, native grapevines may grow vigorously after timber cutting creates an opening in the forest canopy, flooding once shaded areas with sunlight. However, this aggressive growth spurt usually slows down as trees and other plants fill the gap in the canopy. The vast majority of the most severe and persistent invasives are not native to the region.
Plant Provinces of North America
North America's natural vegetation is divided into plant provinces, or regional vegetation types.
Key to Map:
Adapted from North American Terrestrial Vegetation, edited by Michael G. Barbour and William Dwight Billings (New York: Cambridge University Press, 1988).