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Through these pages on plants - flowers, shrubs, trees etc - we have identified several that have been introduced and which have become naturalised. There can be a fine line between invasive and naturalised plants. Or simply confusing.

We happily plant flowers, shrubs and trees in our gardens from around the world, some of which have been specifically bred in nurseries. West Dunbartonshire has some great parks and gardens and is very proud of the historic estates such as Balloch and Overtoun than have amazing collections introduced by collectors on their travels. Having a non-native species is not the problem. The problem is that other plants and the ecosystem itself can be negatively impacted on if some of these get out of hand.

While all invasive plants are, by definition, also naturalized plants, not all naturalized plants are invasive plants. 

Wiki explains that in botany naturalisation is the situation in which an exogenous plant reproduces and disperses on its own in a new environment. 

David Beaulieu writing in The Spruce clarifies it further: 

So, to qualify a plant as naturalized, two conditions must be met:

  • The plant in question must be foreign ("exotic," "introduced," and "alien" are other names used to tell you that a plant is of foreign origin).
  • It must be able to grow on its own and produce a new generation without human aid (for example, without watering, fertilizing, dividing, pest control, or weed control done by human beings). That is, it becomes a wild plant in its adopted homeland. Not all plants introduced from foreign lands are tough enough to naturalize.
  • When a plant naturalizes in an area, this can be either a "good" thing or a "bad" thing, depending on your opinion of the particular plant.

A weed is simply a plant that is in the wrong place. 

That is a very subjective view. Many plants, the dandelion for instance, are amazing in "natural" environments, but a menace in our otherwise neat gravel at home. And plants that may sting, as nettled do, or poisonous to pets, as daffodils, conjour up very different reactions. 

If certain plants have always been here (and that includes any which have been around for many generations) we consider them indigenous. That does not necessarily make them acceptable in all environments, but we generally feel that they belong and even go out of our way to protect them in our wild areas, particularly if these areas are designated nature reserves. We accept that they have specific roles in a balanced ecosystem.

An invasive species is one that is not native that reproduces in a manner that negatively affects native plants and the ecosystem.  

By being neagtively affected, we mean that native plants cannot cope with the competition for space or nutrients in the soil and thereby get ousted. 

Invasive plants may have root systems that take over an area and deter native species. Or they may affect natural pollinators.

Unwanted and uncontrolled plants may spread through dumping of cuttings or even whole plants in wasteland. Or their seeds may be spread by wildlife including insects. But if there happens to be a watercourse anywhere near, they can be spread at an amazing rate.

Open the sub-tabs to see discussion about some of the invasive species that we find around West Dunbartonshire. 

Of particular note are :

BIND WEED : index.asp?pageid=732533

BUDDLEIA : index.asp?pageid=731811

HIMALAYAN BALSAMindex.asp?pageid=732739 

JAPANESE KNOTWEEDindex.asp?pageid=732740

MONBRETIA / CROCOSMIA : index.asp?pageid=732982


A very attractive riverside scene. Himalayan Balsam and meadow bindweed in tight embrace. But they are likely to become a threat to other native plants by the way they oust them.

GARDENERS WORLD : https://www.gardenersworld.com/plants/rhododendron-ponticum/

THE INDEPENDENT : https://www.independent.co.uk/climate-change/news/rhododendrons-invasive-species-temperate-rainforest-b2108031.html

SCOTTISH INVASIVE SPECIES INITIATIVE : https://www.invasivespecies.scot/index.php/about-us

THE SPRUCE : https://www.thespruce.com/naturalized-plants-flora-of-locale-2131090

WIKIPEDIA :  https://en.wikipedia.org/wiki/Naturalisation_(biology)

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