Monday, March 15, 2010

Making sense of conflicting information: the case of the wild radish

One of my interests in life is understanding the world around me.  When I moved to the San Francisco Bay Area, I was initially astonished at how different the botanical world was all around me.  I'd look at the hillsides and have NO idea what I was looking at!  Low flowering plants, trees, bushes... all of this amazingly beautiful stuff, and I didn't know a thing. 

So I did what I like to do... I started learning.  Went to the bookstore and picked up a few wildflower nature guides and identification keys, a sketch pad, a few colored pencils and went to the local hills and started figuring out what flowers were what.  I'd work through the keys (eventually learning what an "inferior ovary" was, and learning how to count stamens).  And slowly, laboriously, I started figuring it out.  

It took me a couple of years (literally!) to figure out 90% of the flowers, and I'm still working on tree identification, but the super-abundance of wildflowers is still my favorite thing to look for in the springtime.  

But this past Saturday I was struck by something really odd.  

Wild radish (Raphanus raphanistrum) is a very, very common flowering plant in the area.  It blooms very early in the spring, and grows nearly everywhere. 

It's in the Brassicaceae family, which means it's related to mustard, broccoli, cabbage (and all "cruciferous" vegetables--so-called because their flowers are cross-shaped).  

But I was seeing it with many different colored flowers.  Some were white, some were yellow, others blue and some even a kind of tawny-gold color. 

Huh?  Were these all the same flower?  Or were there four different species, all of which looked like wild radish?  

I spent a few minutes looking around.  The first place I checked was the Wikipedia article on wild radish, which isn't a bad summary, although a bit short.  

The next thing I did was a regular Google search on [ Raphanus raphanistrum color ] and discovered a pile of articles in Google Scholar (which contains many, many journal articles written by professional botanists). 

{ Why did I use the Latin name of the flower?  Largely because I wanted authoritative articles on the subject.  And I know that the Latin name is used by botanists and horticulturalists, that is, people who would know what's going on.} 

Now, to back up a second to one of the points of this blog... 

Sensemaking, as I think about it, is what people do when they're trying to understand something fairly complicated.  It's the combination of searching information out and then re-organizing what they've found in order to come to a deeper understanding.  

And that's what I started to do with respect to this question of "do wild radishes really come in more than one color?"  

I started with Wikipedia, which told me that they vary "...colour, usually from white to purple but sometimes light orange to yellow, often with colour shading within a single petal"  

Wikipedia also told me that wild radish is sometimes called "Jointed charlock" (a name I'd never heard before), but seeing that also told me that using the Latin name would be the right way to go on my next search.  (That's the problem with wildflowers--they ALL have multiple names!)  

Now, back to the Google Scholar results.  I started looking at the various papers that Scholar found.  The first one I clicked on was "Reproductive biology of petal color variants in wild populations of Raphanus sativus" by a botanist at UC Davis.  I know UC Davis is a good agriculture school with a strong botany department, so I'd tend to believe most of what I find from them.  

In that paper, the author writes that the flowers vary in color from "white, yellow, pink and bronze."  Bronze?  Ah, that's the technical term for what I'd called "tawny-gold."  I also learned that honeybees are the most common pollinators, along with syrphid flies in second place.  ("And what are they?" I think.  Oh ... save it for later.)  

But you see what's happening?  I'm learning more and more from every article I read about wild radishes.  I'd already confirmed my hypothesis about color variations, and now I'm starting to learn why and how such variations occur.  

The article I'm reading now ("Reproductive biology of petal color variants...") is suggesting that the color variations are what drives individual honeybees to prefer one color over another.  (Pink flowers only want to be pollinated by other pink flowers?) 

The next article I look at implies that petal color is determined by one gene site, and that no pure, pre-European contact versions of the wild radish exist... they've all been hybridized by now!  

I could go on.  This turned into one of those diversions that leads to an immense amount of background knowledge about local plants (which is one of the characteristics of people who spend hours identifying plants with a plant key in hand).  

But you see what I'm getting at:  Sensemaking often proceeds from a clearly defined goal ("do wild radishes have color variants in their flowers?"), towards something less defined  ("what's the value of color variants on the fitness of the plant?").  If all you wanted to do was to answer the question, I could have done that on Wikipedia and been done with it.  

Often, though, the beginning question leads to a richer, more nuanced, more informed version of the question.  Sensemaking is often also about how to reformulate your question into something that's richer and deeper, usually by learning about the topic area as you proceed.  

That's what happened in this case.  I now know a lot more about why flowers might want to have variations on their flower colors.  And that's probably knowledge I'll use again in the future.  

I'll see if I can't get some decent pictures of the color variations.  If I succeed, I'll post them here. 

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