15 June 2011

Why scientific names change, and why you should be happy about it

Gardeners LOVE to complain about plants changing their scientific names. I certainly do it as much as anyone else (I even sing about it) but, though I certainly wish the new names could be easier to spell and pronounce, I actually don't mind it too much. Let me explain.

Scientific classification of organisms changes are we learn more about them. Go far enough back in time, and people classified whales as fish. As we learned more about them, however, that classification became obviously incorrect. Whales may live in the ocean, like fish, but they breath air, are warm blooded, and produce milk. Whales, it is clear, are mammals, like us and dogs and elephants, not fish. So the official classification changed.

For as long as scientists have been classifying things, they've been doing it based primarily on what they look like. Taxonomists peer at tiny details of flower structure and pollen grain shape and decide "I think that's an aster" or "Salvia, for sure." Recently, however, there has been a revolution. We've started looking at plant's DNA.

DNA sequence is the ultimate answer for deciding what is most similar. Two plants may look similar, but look at their DNA, and you can see exactly how different they are.

The result has been chaos in the world of scientific names. The genus Aster has been split into a billion pieces. Your Sedum 'Autumn Joy' is now Hylotelephium. It is frustrating (though, you gotta admit, Hylotelephium is REALLY fun to say!) but there is good news. You can't get any more fundamental than DNA sequence, so once this wave of revisions is over, names should be more stable than they have been in the past.

The other good news is the new names actually accurately reflect plant's relationship to each other. And why should you care about that? Well, let me give you an example. Take Hibiscus syriacus, the hardy, shrubby Rose-of-Sharon. Many gardeners still know it as Althea, which is the genus of mallows. Althea, Hibiscus, who cares? Well, you should. Knowing it is a hibiscus, breeders realize that it is closely related to other species of hibiscus, and started trying to make hybrids. One result is this lovely plant:


Hibiscus 'Tosca' (image from Arrowhead Alpines -- where you can buy it!) This is a hybrid between H. syriacus and H. mutabilis with bigger flowers on a bigger, more vigorous plant! Knowing it as althea would only result in unsuccessful attempts to cross it with a mallow. Better names make for better breeding which means better plants for you in your garden.

13 comments:

Alison said...

Thanks for pointing this out. I read about this somewhere else recently (don't remember where), and it makes the changes a little easier to bear.

scottweberpdx said...

It always amazes me that they keep changing the names of things (recently learned that Joe Pye Weed is now Eutrochium). At least the point about DNA makes sense!

Carol said...

This makes perfect sense, and if it means better breeding, I'm all for it! (This will be my "link to post" the next time I point out a new botanical name.)

Tom said...

Call me a plant snob but doesn't it seem perfectly obvious that H. syriacus is closer to a H. rosa-sinensis than an Alcea? Either way they sure are pretty (now that I live somewhere that they'll grow!)

Greensparrow said...

Tom, yes, this example is pretty obvious -- it was just the one that came to mind because of a discussion I was having with someone who knows it as "althea." But in many cases it isn't obvious. I'm hoping that the new revisions of aster and sedum will spawn some exciting new breeding work with those genera.

Green Zebra Market Garden said...

I remember talking with my undergraduate advisor (a phylogeneticist) about "lumpers" and "splitters". I thought these people were just being picky, but your explanation makes much more sense.

Greensparrow said...

Green Zebra,
Well, there are still lumpers and splitters -- you can still have the same data and make different decisions what to call it. Phylogenetics will always be a bit subjective, but DNA sequence makes it a little more reliable.

Leslie said...

According to an article in the June 2011 issue of National Geographic Magazine:

"The list of [scientific plant names] names has … ballooned to 1.05 million, but of those, only around 300,000 are now confirmed to be unique species. Nearly half a million others, it turns out, are redundant.

"The scientific moniker for English oak has 314 synonyms, the common daisy 29, and the giant sequoia 18."

Hopefully changing the scientific names will also clear up this mess. When there are just as many Latin names for plants as there are common names, everyone just gets confused! Plus, I'd much rather learn just one name per plant. That's hard enough.

Scott said...

Thanks, Joseph, for the nice, clear post. As a name-changing taxonomist by profession, I sympathize with the need to learn new names (I have to learn them, too), but I love knowing that our classification more closely reflects the actual evolutionary history.

Tom said...

Sorry, I wasn't meaning to insult you if it came off that way. I actually didn't know Althea was ever it's latin name, I thought it was just another common name. I really would like to know what characteristics they used to separate it from Hibiscus originally... I am still trying to wrap my head around all the aster and sedum divisions though... I almost don't want to think about it!

Jenn said...

A pelargonium is not a geranium.
And hasn't been since 1738.

I'd really like the convention to come round on this one.

Yeah, it's a peeve. What can I say. Fits the discussion here, I think...

Bom said...

I enjoy learning the scietific names of plants that I have. I wish things could be simplified. Is there a way to gradually remove the synonyms?

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