I just searched the archive for "nectar" and "source" and got some
interesting info.  Has anyone written about methods for tracking bees'
sources?  For pollen I think the logical thing would be to collect dropped
nuggets of pollen and examine them under a microscope.  Each family of
plants should have a recognizable shape and size of pollen grain.  A guide
with photos of various pollens would be helpful. 

I live and keep bees in urban Chicago.  There are many ornamental trees,
shrubs, flowers, and some weeds.  Bees never seem short of pollen here, so
nectar is more the issue.  Has any method been developed to positively
identify what flowers the bees are going to?.  Some plants are not obvious
but may be discovered by accident.  For example, the Bee-L archive mentions
the very inconspicuous flowers of Boston Ivy (Parthenocissus tricuspidata).
 It's a large and abundant urban plant that blooms in June.  

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