Well now, Wordwind, just how much do you want to find these boards? One way is to start with searching for various Universities, (U of NH) getting to the college you are interested (Agriculture)then the department (botany) and sending a message (there's usually a "Contact Us" button) to the department chair asking for boards in that field.
When I have had research to do, I've found the Profs were kind about steering me in the right direction -- although, be warned they may be slow in answering. For local colleges sometimes a phone call is faster! As an aside I've found Profs more amenable in mid afternon - (after a good lunch?)
Also, you can search for organizations that promote a specific subject National Potato Board, Nat'l Assn of Foresters, Ham Radio Operators of New England..... you get the idea.
It can be a bit tedious at times but there are also some great surprises!
And awaaay you go!
