Sometimes as I read my gardening books and magazines I come across a Latin plant name followed by a parentheses that says another name the plant was formerly known as—which is often more familiar to me. Why do the plant namers do this to us?
Answer: Changes in long-established names are a nuisance for everyone and may seem difficult to justify—especially where a familiar name changes to something that is hard to remember and to spell, and even more difficult to pronounce. However, there are usually good reasons for the change.
The “principle of priority,” as it is known, has established that the first written description of a plant is taken as its valid name. Familiar names can therefore sometimes fall from grace as new information comes to light from ever more obscure places around the globe. Herbaria in libraries in the former Soviet Union are now being studied by experts and we are having to accept earlier names for some plant familiar to generations of gardeners. The “new” name may mean nothing to us and may be very hard for some of us to pronounce—try saying Allium przewalskianum quickly.
Another reason for name changes is that modern scientists are able to detect ever more minute differences (and similarities) in plant characteristics. This means that sometimes new plants must be separated into a new genus: our old friend Senecio ‘Sunshine’ became Brachyglottis ‘Sunshine’, while the once-familiar genus Cimicifuga has disappeared into another genus, Actaea. As for the florists chrysanthemum, it was Dendranthema only to be returned to Chrysanthemum a few years later. Occasionally taxonomists run out of names and resort to using an anagram of an existing one: the genus Saruma has been created from the closely related Asarum.