June 23, 2007 11:01 AM

A friend asked...

A friend who studies graphic design asked:
Speaking of,[plants] wikipedia tells me that "The classification of all flowering plants is currently in a state of flux." (as found in http://en.wikipedia.org/wiki/Carnivorous_plants). Is that true? Why's it the case? I haven't read the full wiki article so I apologize if it's answered like two sentences down.

My response:
Yes, it's in a major state of flux! As more is understood about plant genetics, we're understanding plants much better.

Now that we're looking at the genetic data, we can look at the plants in a new context, and find new similarities. Now we're making the family trees from genetic base pair similarities, then adding the physical traits to that genetic tree. We're even trying to figure out what genes give rise to what traits, but we have only started mapping this out for a few test plants (arabadopsis, corn, and rice).

You see, botanists have always based their classifications on traits. Now, with genetics, we have more distinct traits on which we base the relationships (our traits are super basic - A,T,G...). The guys in the 16th century would say, "These plants have similar leaves (bark, flowers, number of flower parts, etc)." Those were their traits. Then they would make a family tree.

Older trees, for the most part, are matching up with current genetic findings - but not always! We're learning that many plants are not as closely related as we thought - and many plants are closely related that we never thought to put together. For instance, look at Dr. Charles Davis' work at Harvard: they used genetic data to determine that a family of leafless saprophytic flowers (otherwise impossible to place) is nested within the Euphorbiaceae - a very diverse group of flowering plants that includes old-world cactus-looking succulents, the rubber tree, and poinsettia.
Link from Science Magazine: http://www.sciencemag.org/cgi/content/full/315/5820/1812?maxtoshow=&HITS=20&hits=20&RESULTFORMAT=&author1=Davis%2C+C&andorexacttitle=or&andorexacttitleabs=or&andorexactfulltext=or&searchid=1&FIRSTINDEX=0&sortspec=relevance&fdate=7/1/1880&tdate=6/30/2007&resourcetype=HWCIT
Link from Smithsonian Magazine: http://www.smithsonianmagazine.com/issues/2007/march/wildthings.php

My primary interest in plants is making genetic trees, then finding developmental similarities and differences, which will basically stand as tic marks on a tree. People can later compile these physical traits into a key, then use the key in the field to identify plants.

In the Specht lab, I'm working with ginger relatives (Zingeberales), and dessicant-tolerant (Cheilanthoid) ferns. This Fall, I'm hoping to work with woody tropical vines (Freycinetia and Pandanus).


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