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Invasiveness is subjective; it can vary from zone to zone, and garden to garden. In general terms, invasive plants are characterized as such because they exhibit one or more of the following tendencies:
1. Rapid, unchecked growth (which may require certain conditions; under adverse conditions, the plant's growth may be moderate);
2. Spreading by seed into areas where the plant is not desired and/or cannot be contained;
3. Spreading by runners or roots, which choke out or crowd other desirable plants (whether native or cultivated); and/or
4. Causing harm to the environment (For example, water hyacinth cuts off waterways in warm climates; kudzu vine smothers out and kills vegetation, including mature trees.)
5. An adjective describing an autonomous quality found in plants we don't like. When plants we do like spread themselves around the garden, we tend to place the blame squarely on ourselves. See green thumb
Any plant, especially one that is non-native to an area that grows too well in it and becomes difficult to control and/or can threaten native plants....
'Naturalized' is another word for 'invasive'. The terms ‘invasive’ and ‘weed’ are emotionally charged and based on subjective assessments. Depending on place and time a so-called ‘weed’ can become desirable and is even cultivated by the nursery trade.
Note the current popularity of Joe Pye Weed, Eupatorium purpureum, and Orange Butterfly Weed, Asclepias tuberosis). Japanese Knotweed, Fallopia japonica, and Elderberry, Sambucus canadensis, which makes a very functional sun-or-shade blind or hedge where other plants fail. If the objective is to 'naturalize' a species to form a blind or border then you want a plant that is fast-growing and ‘invasive’.
In a class on invasive species ecology and management the heated argument on this definition came out with one that was the most useful when talking about the environment;
Invasive species- An organism (plant) transported out of its native range (usually by humans, rarer by nature) and which has spread/is spreading/is able to spread into natural areas in a new range.
This is in contrast to Aggressive plants, which show an ability to outcompete other garden plants but which fail to disperse and survive to reproduction in the surrounding native environment. Note this definition eliminates the subjectivity of invasiveness, but a plant's status also should place it in a geographical context (zone, habitat, pH, etc.)
invasive by rhizomatous roots as well as seed. crowds out dired plants and impossible to pull . grows abundantly and saps all fertilizer from desired plants. runs underground, including under concrete. dollar weed is charming compared to this!
invasive by rhizomatous roots as well as seed. crowds out desired plants and impossible to pull . grows abundantly and saps all fertilizer from desired plants. runs underground, including under concrete. dollar weed is charming compared to this!
"Invasive species" is legally defined in the US by Executive Order 13112 “ as "an alien [non-native] species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” "Non-native" will depend on the ecosystem in question. Economic and environmental harm are difficult and expensive to assess and quantify. Harm to human health is easier to pin down. I don't know how many of the plants on this site that are characterized as being invasive really fit the legal definition. Perhaps "can become a weed" might be more appropriate, using "weed" in the sense of being unwanted. Gardeners understand that term perfectly.
