[R] count data with nested mixed effects

[kohn at botany.utoronto.ca]

Dear R-Pros,
I have count data in which 6-10 points are nested within 17 larger units
(which are nested within 3 larger-still units) plus a number of
covariates.  It could be nested ANCOVA but for poisson family.  Could
someone kindly advise me 1) if lmer is the correct function for the
analysis? and 2) what synax expresses the error structure?  I have
consulted the package HTML documentation but am not experienced enough to
get it.
Many thanks,
Deborah