HOW many people look carefully at the plants and animals when walking through parks and green spaces?

Would you know a native species from a non-native? A native species is defined as anything which has been on this island since the last Ice Age (some 10,000 years ago).

But in recent years, invasive (spreading) non-native species from other countries have been introduced to Britain's countryside by man, largely with detrimental consequences.

Glasgow is no exception - in the city's many parks and rivers, a host of invasive species can be found.

Perhaps the most well-known is the grey squirrel, introduced to Britain from America as early as the 19th Century.

It is bigger than our native red squirrel and will eat almost anything, including young tree buds and bark, damaging trees.

It adapts very quickly to habitats, particularly towns and cities, and is a carrier of squirrel-pox which fatally affects the native red squirrel.

As a result, the grey squirrel now vastly outnumbers the red with a population in excess of 2million, compared to only 150,000. Did you know it is an offence to release grey squirrels in the UK?

Another alien invader is the American mink, brought to British fur farms in the 1920s.

The few mink that escaped to the countryside then, have now increased to approximately 100,000 today. These small chocolate-brown weasel-type animals are great swimmers, climbers and opportunists, finding and eating animals such as our native water vole which are in sharp decline.

However, the good news is that native otters are making a huge recovery as our rivers become less polluted and findings suggest mink are less prevalent in these areas.

Perhaps the most famous of the invasive plants is the Rhododendron Ponticum, originally found in the Mediterranean and Asia, and introduced to Britain in Victorian times as an ornamental shrub producing beautiful purple flowers.

Today it can be found carpeting parks, woodland estates, moorland and mountains. It grows densely and spreads by thousands of seed from just one flower head.

Last but not least, the majestic Giant Hogweed grows to some 10 feet tall producing huge circular plates of whites flowers.

It is a spectacular plant but the sap can burn the skin.