WHAT'S IN A NAME?

If you've despaired of why botanists keep changing the names of your favourite plants, columnist Ken Thompson explains the logic behind the taxonomic tinkering

- Ken Thompson

Gardeners, I think it’s fair to say, have a fairly fraught relationship with plant taxonomy. Botanists want the way plants are classified and named to reflect our best understanding of their evolutionary relationships. Gardeners just wish they would leave well enough alone.

In recent years, the whole subject has been revolutionised, in part, by our ability to look directly at plant DNA, which has often revealed that some of our earlier ideas weren’t quite right, and that plants’ names need to change.

Aster 

But change how? Sometimes we need new names, and a good example is Aster. When Carl Linnaeus was handing out our modern Latin binomial names, he picked the European aster as the ‘type’ species of his new Aster genus and called it Aster amellus.

Quite a few other European plants looked rather like the European aster, so these were added to the new genus. Later, botanists found an absolute cornucopia of asters in North America, including Aster novi-belgii, the New York aster, and Aster novae-angliae, the New England aster. These two are the plants that are most often called Michaelmas daisies, and these days it’s hard to imagine the autumn garden without them.

Aster just grew and grew, but suspicions developed that not all those plants belonged together, suspicions confirmed by the new DNA evidence in the mid-1990s.