Photo: Arne Ader
Canada goldenrod Kanada kuldvits Solidago canadensis
The Canada goldenrod grows since a long time in our gardens and as a late summer flowerer with a long flowering period the tall plant has been an ornament of garden beds for long. About 25 years ago we noticed the Canada goldenrod on the verges of our roads and on wastelands but also taking over in meadows. By today the invasive Canada goldenrod is one of 13 plant species whose seeds or seedlings must not be imported, sold or planted in Estonia – we have to do with almost as threatening a plant with regard to its spread as the Heracleum or hogweed, well known to all, that is being fought in our nature already for years.
Generally alien species can become threatening when they arrive into a new biotope where they become more aggressive or dominating, crowding out local species, thus transforming our own natural biotopes. In areas where for various reasons the expansion of some alien species is marked even native species may turn expansive (the species starts to proliferate for some reason). The reasons may be many and very varied. Scientists throughout the world are engaged in the study of invasive species.
In any case incoming alien species and their distribution must be monitored and the dates when the alien species begins to spread on its own, starts an expansion, must be noted.