They are beautiful, have bright colours, grow quickly and can be purchased in garden centres. Why deprive yourself of it? But they are not part of our plant heritage, far from it !
They are always plants that man has sought from the other side of the world to adapt them to our regions, without really being aware of their possible impact on other species, those ones are well native. It is only by seeing them develop and replace usual vegetation very quickly that we realize the danger of their proliferation in nature outside the boundaries of our gardens. Because we are never the only ones involved in their dissemination: the wind mainly takes care of it, but small rodents and especially birds also transport the seeds to a neighboring area. The plant can thus quickly reach fragile natural areas.
If the introduction of these invasive species is easy, their eradication quickly becomes a nightmare. Some seeds can remain inert for a long time and germinate years later. Rhizome plants are incredibly prolific because even when ground, they can still give birth to new individuals. It is enough to consult on the Internet the many forums where Internet users launch SOS to be convinced of this.
Amateur gardeners must be informed because it is they who are now involved in their dissemination. And only they can limit their impact.
A plant is said to be invasive when its invasiveness is not due to ephemeral variations in climate or environment, but to its own qualities such as a rapid growth rate or the production of fatal toxins for neighboring species.
The Environment Department of the Communes' Community of the Pays d'Iroise
provides you with two excellent documents in french, that you can download by clicking on the pictures below :