Dave and Steve: The paper by McCrea and Levy provides for a way of
visualizing the UV component of flower reflectances on colour film
(slides). However UV and blue are not readily distinguished by this
method and as McCrea and Levy point out, their methods must be used
with great care and they outline the caveats thoroughly. Their
method does not use trichromaticity principles in a rigorous sense.
It is not clear that their method is any less cumbersome than any
other so far used.
 
Cheers, Peter