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name change for Eupatorium- please tell me about this...

Posted by christinmk z5b WA (My Page) on
Sat, Jul 11, 09 at 21:57

Hi guys! I know nothing about Botony, but was hoping someone here might be able to answer my question. First of all, I hardly ever pay attention to brand new changes of name in the plant world, but happened to read about this on the Lazy SS Farm site. It noted that Eupatoriums (and many others in the Asteraceae family) were going to have a serious name change, like Actaea did a while back. I read a little about it on another site (link below, scroll down) but was hoping someone could explain this to me.

Is the genus 'Eupatorium' just going away completly? Or are there still plants in that genus? So my E. maculatum will be now Eutrochium maculatum? How about my Eupatorium dubium 'Little Joe'? Also a Eutrochium? And Eupatorium rugosum 'Chocolate' will now be Ageratina?

I do get the need for these changes(I think ;-) Some plants are lumped into the wrong genus when they should be with another, or in one all thier own. They are not genetically related. Right?
If this is so, why was Cimicfuga changed to Actaea? Was there another plant that was the 'real' Cimicfuga and the plants that did not belong with it were changed to Actaea? If that is not the case, why did they bother to change it all up?

Just curious, how long do you think it will be before plant sources/stores start selling Eupatorium under its new names?
Thank you!

Here is a link that might be useful: more info....

Follow-Up Postings:

RE: name change for Eupatorium- please tell me about this...

Unfortunately who ever wrote the text of the page you linked did not include citations so it is hard to say how recent the information is. Placing Eupatorium rugosum in the genus Ageratina goes back to a paper by King and Robinson in 1987, where they note that Ageratina has twice the chromosome number of Eupatorium and different pappus morphology. In 2000 Schmidt and Schilling released DNA evidence that supports this assertion, and suggest that retention of Ageratina in Eupatorium would require the inclusion of several other genera including Liatris for the genus to remain monophyletic.

The placement of E. maculatum and E. purpureum in Eupatoriadelphus (not sure where Eutrochium comes from...maybe a more recent paper?) is not as strongly supported by the Schmidt and Schilling paper because they found that Eupatoriadelphus was sister to Eupatorium, making the split arbitrary (the old lumper vs. splitter argument)

Some people are quick to use new conventions as they are published, while others may read through the data and decide to wait until more data becomes available if the current is not compelling. Personally I am inclined to keep old names unless DNA evidence shows that the older groups are not monophyletic.

RE: name change for Eupatorium- please tell me about this...

Thanks lycopus! Some of the scientific lingo you used went right over my head, but you did answer some questions.
So it is safe for me to keep calling them Eupatorium?

RE: name change for Eupatorium- please tell me about this...

There is nothing wrong with using the old names and for most people Eupatorium is probably what they are most familiar with. The old names are considered synonymous with the new ones.

A botanist would probably prefer to use the most recent nomenclature, provided they accept that it is appropriate. In a manuscript the first mention of a plant should be followed by the authority, for example Eupatorium rugosum Houtt. would be the old name and Ageratina altissima (L.) King & H. Rob. would be the newer name for White Snakeroot. So here King and Robinson (1987) is the publication being cited as the authority for Ageratina altissima.

Alternatively an authority for all plant names can initially be given if you want the following the naming conventions of one publication. This is useful if you are following a regional flora.

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