The argument often made for using scientific plant names is that it provides consistency. If you ask for Alchemilla mollis that is what you’ll get. The problem is you keep finding different people referring to the same plant with different names. The exact opposite of what is wanted and causing confusion and irritation to many gardeners – what we want is clear stable names with no grey areas. Unfortunately “grey areas” are hard wired into the system of naming livings thing.
The names of all living things, plants, animals, bacteria, politicians (possibly), etc are an attempt by mankind to order the world around us. To look at the state of things that may not seem to obvious a human obsessions but our history is littered with mans attempt to bring order and explanation to the world around him. To this end biologists try to group things in collections of related examples. This lead to plants and animals being divided into separate kingdoms and these were further divided and subdivided so like species were grouped into genera and like genera into families and so on. As this was going on it became clear that the range of species around us had changed over time, or evolved, and so it made sense to reflect these ancestral links in the arrangement of species, etc.
This hit two major stumbling blocks. The first and most obvious was the lack of
information about these ancestral forms. The vast, vast, VAST majority of species are extinct and lost forever. It needs a very unlikely set of circumstances for a plant or animal to be preserved as a fossil and even then the amount of detail preserved is still very limited. The other problem was how species evolve themselves. Initially it was believed that species were distinct with clear boundaries of some sort separating different species. Then came; Charles Darwin and Alfred Russel Wallace. Few people cannot have heard of Darwin but Wallace deserves his share of the credit for the theory of evolution Darwin explained in his book “The Origin of Species”. What the 50 year old Darwin wrote about was a bloody life and death struggle between all living things. This was the driving force behind the gradual change from one form into a new one. No longer were species entirely separate entities but a snap shot on their evolutionary journey.
So we find ourselves in a situation where it is impossible to have a clear definition of what a species is and nearly all the information we need to arrange the extant species in their places in the evolutionary map is lost for ever. I can best describe the situation thus: imagine you photograph everyone walking down you local high street one Saturday, lay all the pictures out and with only the pictures to go on try and work out not only who is related to who but how closely. I can guarantee you will disagree with who ever you are working with and have to frequently change your mind.
Now for the next question – why don’t we end up changing plant names more often?