I'm finding it mainly in article titles and on sites that reference
medicinal uses.

This is a link to a PubMed reference that has the n.o. in the title:
http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum

And here is a link to a botanical site that I've been perusing:
http://botanical.com/botanical/mgmh/s/snaker56.html

When I search sites such as the USDA Plants Database, the n.o. doesn't
appear.

Thanks!