A native plant is a species that has evolved naturally in a particular region for thousands of years. These plants are the biological foundation of the ecosystem, adapting to local climate, geology, and soil conditions without human assistance. They represent the original flora that supports the complex web of life in a given area. Understanding their role is important for recognizing the health and function of any local ecology.
Defining Native Plants by Time and Place
Defining a native plant relies on two primary ecological criteria: geography and time. A plant is considered native only if it occurs naturally within a specific geographical range, which can be as small as a local watershed or as large as an entire ecoregion. The concept of “native” is geographically precise, meaning a plant native to one state may be non-native just a few hundred miles away. The temporal boundary is equally important, establishing a baseline before significant human-caused alterations to the flora of an area. In North America, this baseline is generally established as the period prior to European settlement, when species distribution occurred only through natural processes like wind, water, or animal movement.
Distinguishing Native, Introduced, and Invasive Species
The terminology used to describe a plant’s origin can be confusing, but the distinction between species types is based entirely on their ecological impact. A native species has co-evolved with the local ecosystem, forming balanced relationships with surrounding organisms. An introduced species, also called exotic or non-native, is one that has been brought to a new area by human activity, either intentionally or accidentally. These introduced species can thrive in their new location without causing measurable harm to the existing ecosystem, often becoming naturalized.
The third category, the invasive species, consists of introduced plants that aggressively spread, outcompete native flora, and cause environmental or economic damage. Invasive plants succeed because they have left behind the natural predators, diseases, and herbivores that kept their populations in check in their original range. They displace native plants, reducing biodiversity and disrupting co-evolved relationships.
Ecological Interdependence and Specialized Relationships
Native plants are essential components of the local food web due to millions of years of co-evolution with local fauna. This process has resulted in highly specialized relationships, particularly between plants and insects. Many native insects, for example, have evolved to feed only on specific native host plants, often due to the unique chemical defenses the plant produces.
The classic example involves the Monarch butterfly, whose caterpillars can only consume milkweed plants because they have developed the physiological ability to sequester the plant’s cardenolide toxins. Similarly, many native bees are specialized pollinators, possessing the correct tongue length or behavioral pattern to access the nectar and pollen of only a few native plant species. Native plants are significantly more attractive to local pollinators than non-native alternatives.
Below the surface, native plants also maintain a specialized relationship with local soil biology, particularly with mycorrhizal fungi. These fungi form extensive underground networks of thread-like hyphae that connect to the plant’s roots. The plant provides the fungi with carbohydrates produced through photosynthesis, and in return, the fungi act as an extended root system, vastly increasing the plant’s ability to absorb water and mineral nutrients like phosphorus and nitrogen from the soil. This mutualistic symbiosis is integral to the plant’s resilience and soil health.
Sourcing and Selecting Authentic Native Plants
For those looking to support their local ecosystem, the process of sourcing plants requires attention to detail beyond just the species name. It is recommended to seek out local ecotypes, which are native plants grown from seed collected within a specific, nearby geographic region. These local ecotypes possess the genetic adaptations necessary to thrive in the microclimate and soil conditions of that immediate area, ensuring the best chance of survival and local ecological function.
A common pitfall is the selection of “nativars,” which are cultivars—or cultivated varieties—of native species that have been selectively bred for traits like compact size or different flower color. While nativars are derived from native stock, the selective breeding process can unintentionally compromise their ecological value. For instance, plants bred for double blooms may make pollen and nectar inaccessible to specialized insects, or those with altered leaf color may lack the specific chemistry needed to serve as host plants for larval caterpillars. Choosing the “straight species,” or the original form of the native plant, is the most reliable way to ensure the plant provides the full ecological benefit.