Tim,
Thanks for your suggestion -- worked exactly as you described. And it's a good enough solution, although it doesn't give me quite what I want, because, in the original legend, I get, for example, the species indicator ("CBL"), with a yellow circle with the year ("2009") next to it. After ungrouping, I'd ideally like to have just "CBL" plus the yellow circle, but I don't see a way that I can edit the "2009" out of the legend.
Rick