A big caveat about the plants section of NCBI taxonomy is that they chose (for genetic reasons) to use the quite incomplete APG system instead of the more universally used Chronquist system.  More about the differences at:
http://www.botany.hawaii.edu/faculty/carr/pfamilies.htm

Soaring Bear Ph.D. Pharmacology soaringbear at yahoo.com
http://soaringbear.com/nature/WeedsforNeeds.html
http://www.nlm.nih.gov/mesh/presentations/bear_2005_aug/index.htm
author of http://HerbMed.org & http://HerbInsight.com

--- On Sat, 7/11/09, Roderic Page <r.page@bio.gla.ac.uk> wrote:

I've been playing with expressing the NCBI taxonomy in TDWG RDF. The 
results are described at http://iphylo.blogspot.com/2009/07/ncbi-rdf.html
  (see also http://iphylo.blogspot.com/2009/07/ncbi-taxonomy-tdwg-vocabularies-and-rdf.html
  for some background).

It's still incomplete (I've not put links up and down the tree yet), 
but for now the focus is on expressing links to nomenclators that 
support LSIDs (such as IPNI and Index Fungorum) so that I can annotate 
the NCBI taxonomy via SPARQL queries.

One minor comment, the property "rankString" has been deprecated 
(apparently), but it makes sense to retain this as there may well be 
ranks that a classification has that aren't in the TDWG vocabulary. 
Hence, I'd be keen for this NOT to be deprecated.

Regards

Rod

---------------------------------------------------------
Roderic Page
Professor of Taxonomy
DEEB, FBLS
Graham Kerr Building
University of Glasgow
Glasgow G12 8QQ, UK