Native, Invasive, and Other Plant-Related Definitions

Native Plant

A plant that is a part of the balance of nature that has developed over hundreds or thousands of years in a particular region or ecosystem. Note: The word native should always be used with a geographic qualifier (that is, native to California). Only plants found in this country before European settlement are considered to be native to the United States.

Endemic Plant

A plant that is found only within the borders of California. We have a unique environment in California and it shows with a large number of plants that grow here and nowhere else. Many native plants would be considered Endemic but they also grow just slightly beyond the borders of our state.

Invasive Plant

A plant that is both non-native and able to establish on many sites, grow quickly, and spread to the point of disrupting plant communities or ecosystems.

Non-Native Plant

A plant introduced with human help (intentionally or accidentally) to a new place or new type of habitat where it was not previously found. Note: Not all non-native plants are invasive. In fact, when many non-native plants are introduced to new places, they cannot reproduce or spread readily without continued human help (for example, many ornamental plants).

Naturalized Plant

A non-native plant that does not need human help to reproduce and maintain itself over time in an area where it is not native. Notes: Even though their offspring reproduce and spread naturally (without human help), naturalized plants do not, over time, become native members of the local plant community. Many naturalized plants are found primarily near human-dominated areas; and, sometimes, naturalized is used (confusingly) to refer specifically to naturally reproducing, non-native plants that do not invade areas dominated by native vegetation. However, since invasive plants also reproduce and spread without human help, they also are naturalized invasives are a small, but troublesome, sub-category of naturalized plants.

Exotic Plant

A plant not native to the continent on which it is now found. (Plants from Europe are exotic in North America; plants from North America are exotic in Japan.)

Translocated Plant

A plant not native to the portion of the continent where it is now found. (California Poppies in New England are an example of a translocated species.)

Opportunistic Native Plant

A native plant that is able to take advantage of disturbance to the soil or existing vegetation to spread quickly and out-compete the other plants on the disturbed site.

Weed

Common Usage - A weed is a plant (native or non-native) that is not valued in the place where it is growing (USDA Animal and Plant Health Inspection Service (APHIS)). Definition - Any plant that poses a major threat to agriculture and/or natural ecosystems within the United States.

Noxious Weed

Common Usage - A plant that is particularly troublesome. Legal Context (Federal Plant Protection Act) - Any plant or plant product that can directly or indirectly injure or cause damage to crops (including nursery stock or plant products), livestock, poultry or other interests of agriculture, irrigation, navigation, the natural resources of the United States, the public health, or the environment. Note: USDA APHIS maintains a list of federally-recognized noxious weeds. It is illegal to import Federally listed noxious weeds or transport them across state lines.