Learn the definitions of “invasive,”
“non-native,” “native,” “pest,” and “weed.”
Jump or scroll to: ~What is an invasive species? ~Are all non-natives invasive? ~Maryland Definition of Invasive Plants ~Takoma Park residents learn what invasives are
What is an invasive species?
“An ‘invasive species’ is a species that is:
1) non-native (or alien) to the ecosystem under consideration and,
2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.”
Federal definition established by Executive Order 13112, signed by President Clinton, February 3, 1999.
Click to go to the USDA National Invasive Species Council, What are Invasive Species? for more information on this definition.
Are all non-natives invasive?
No, all non-native species are not invasive. However, by definition, all invasive species are non-native.
Click to watch a 4-minute video on the definitions of “native,” “non-native,” and “invasives.”
Invasive species = non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health (U.S. federal definition)
Native species = has evolved in a given place over a period of time sufficient to develop complex and essential relationships with the physical environment and other organisms in a given ecological community (Darke and Tallamy, see “Native Tree” Defined)
Non-native species = not native (i.e., alien) to the ecosystem under consideration
Maryland Definition of Invasive Plants
Click to go to current MDA Invasive Plant List.
Maryland Department of Agriculture regulates the sale of invasive plants. Until recently, Maryland’s Invasive Plant Advisory Committee (IPAC) has used a weed assessment protocol to determine whether to advise the Secretary of Agriculture to classify an invasive plant as
- Tier I (a person may not propagate, import, transfer, sell, purchase, transport, or introduce any living part of the plant in MD) or
- Tier 2 (a person may not sell or provide landscaping services to plant the plant without informing the customer).
Relatively few invasive plants in Maryland “pass” this protocol to be declared Tier 1 or Tier 2 invasives. The current MDA Invasive Plant List is relatively short for that reason.
That situation is in the process of changing, due to the Biodiversity and Agriculture Protection Act — sometimes called the “invasive plant species bill” — went into effect in June 2024. A new invasive species list was supposed to replace the tier classification system by October 2024. The wording of the regulations based on the bill are still under discussion. Learn more about this bill…
Click here to learn more about classifying plants as invasive.
Takoma Park Residents Learn What Invasives Are
Bob Gibson gets educated about invasives versus non-natives
“…many of us in Takoma Park filled our gardens with plants to add beauty and greenery with little or no awareness that many of our choices were … invasive.”
Meg explains why so many Takoma Park yards are overrun with invasives
“Have you ever wondered why so many invasive plants pervade our yards? Consider my own experience.”
Friends of Native Trees in Takoma 