We tend to think of plants as being either wild or cultivated. Our gardens, public and private – and indeed the countryside – are made up from a vast array of plants from around the world. A very small percentage of these are actually native to the UK. Many others have arrived here, or been introduced over many years, from Europe, China, Japan, America, Africa and Australasia.
Let’s start with what we consider to be our native or wild plants in the UK. These are now divided into four distinct categories. Note: we are only looking at the Vascular Plants here (Flowering plants, Conifers and Ferns), not fungi, mosses, lichens or algae.
True Natives: these arrived here after the last Ice Age by natural colonisation. Our true natives include our Queen of the Woods – the Silver Birch (Betula pendula) – our majestic Oaks (Quercus robur), down to (what you may consider as lawn weeds) the White Clover (Trifolium repens) and Dandelions (Taraxacum sp.)
Archaeotypes: these are the ancient introductions – plants that were introduced prior to 1500 AD. Many of these came from Europe and were introduced for edible or medicinal purposes, such as the Sweet Chestnut (Castanea sativa). Others may have hitched a ride – arriving here accidentally – such as Field Poppies (Papaver rhoeas). Many of these are now considered part of our native flora.
Neophytes: are the plants introduced since AD1500, usually by plant collectors and explorers, which have escaped from our gardens and become naturalised in our countryside. Some of these are now classed as ‘non-native invasive species’ – such as Japanese Knotweed (Fallopia japonica) and the aquatic New Zealand Pigmyweed (Crassula helmsii) – are a menace to our countryside and extremely difficult to control. Others, such as Michaelmas Daisies (Aster sp.) and Montbretia (Crocosmia sp.) add to the floral variety of our ‘wild flowers’. The Butterfly Bush (Buddleja davidii) is in this category. This has given rise to hundreds of named cultivated garden forms.
Casuals: the final group of plants that may be found in our countryside are the non-native and non-naturalised varieties. This is a small, but ever-changing group, particularly with the destruction of ‘natural’ habitats and climate change. Many of these may become reclassified as Neophytes if found to survive and spread in our countryside.
Using the above definitions to consider our native flowering plant flora produces a figure of just under 3,000 species. Natives (1407), Archaeophyte (149), Neophytes (1155) and Casuals (2490).
When it comes to garden and cultivated plants – all the non-native and exotic introductions currently growing in gardens across the UK – a complete inventory has never been attempted. Have a guess at the number of species – and I will continue on these next week.