Non-native plants are continually being introduced into natural ecosystems. These introductions occur by accident, when non-native species hitchhike to the U.S. on ships, planes, cars, or people. Quite frequently, however, non-native species are intentionally introduced. A good example of this is the use of non-native species as ornamentals for lawn and garden beautification. Of all the non-native species in the U.S., a few will demonstrate extreme vigor and competitive ability in their new habitat, and are referred to as invasive species. Famous examples of invasive species include: kudzu, garlic mustard, Japanese honeysuckle, and multiflora rose. The debate is ongoing concerning what characteristics allow particular non-native species to become invasive. Whatever the cause, invasives represent a major threat to native biodiversity in the U.S. due to their ability to outcompete native species. Once established, invasives often form dense, monotypic stands that prevent native re-establishment in the area.

Multiflora and ginseng.jpg

Ginseng in multiflora rose tangle, from study. 

Credit: McGraw Labs, WVU

Despite being a plant that favors shady, deep deciduous forest woods (which tend to have fewer invasives than many other habitats), ginseng has not escaped exposure to, and impacts of, invasive plant competitors. Wixted and McGraw (2009) found that about two-thirds of ginseng populations contain at least one invasive species. In addition, about one-third of all ginseng individuals were found in close proximity to invasive plants. Further experimental studies with garlic mustard showed negative effects on young ginseng plants, especially in terms of survival of the youngest plants. Most invasive species’ interactions with ginseng have not been studied. Therefore, more research is urgently needed.

(1) Wixted and McGraw 2008?(Wixted, K. and J. B. McGraw. 2009. A Panax-centric view of invasive species.)
(2) Wixted and McGraw 2010. 
Competitive and allelopathic effects of garlic mustard (Alliaria petiolata) on American ginseng

(Panax quinquefolius).

What can you do to discourage invasive species?

(1) If you are a landowner, identify, learn about, and try to keep invasive species at a minimum.

(2) Stay tuned to your local and state extension to learn about invasive removal efforts and invasive threats in your area.

(2) Encourage holistic ecosystem management for the good of all biodiversity.

Wild American ginseng, emerging in spring with Japanese stiltgrass (Microstegium vimineum). Credit: batcavebotanicals, 2022