In the United States, each county has an office of the US Department of Agriculture Natural Resources Conservation Service; in my state, they are co-located with the Soil & Water Conservation Districts. You will find a great deal of information regarding native & non-native plants & invasive species-- as well as tons of other stuff from those offices. The "Poison Plants" book is VERY helpful, too. The USDA also has a plant website at http://plants.usda.gov/ that is a huge database.
Yes it is worthwhile to utilize these offices. That is what they are there for. This all happened to me before Dr. Deb's PP book came out.
I would like to have it anyways to look stuff up. Also, she goes into plants high in sugars, etc. which is also very important information to have. I cannot believe how much I have read on this forum regarding the ill effects of these grasses on horses.
Very important to find out exactly what our horses are eating.
I was shocked to find out I had a deadly plant growing, and we had quite large patches of it. I moved my horses to our neighbors place while we took care of the bulk of it as this was before we cross-fenced.
They had it growing in their corral and had no idea what it was. When I saw they had it, well it was like in a horror movie when the "psycho" music starts playing !!!! Luckily, their pasture land was ok. Even more lucky, the horses did not touch it as they had LOTS of other grazing.
Update: The issues (aggressive towards horses when being ridden and the dislike of being in the stall) seemed to be getting worse. My horse seemed constantly distracted and in a state of constant movement. I jokingly (sort of) asked my vet about getting a script for horse ritalin. We discussed hormone issues, pasture issues and training issues. I decided to do some more reading and thinking before making any decisions. I started to realize that the issues had gotten much worse since moving to our current barn. I walked the fields and didn't find much clover. I changed from doing full board to a self care situation. This allowed me to change her feed and hay. With in a week of changing her from a generic sweet feed (basically junk) to a ration balancer she was calmer. I rode with a friend on a horse we never met before and my horse only gave her one mean glance. In the stall she is calmer too. People are surprised when they realize she is in the stall- everyone says, "wow she isn't kicking". She still lives out 24/7 with a run in shed and hay all the time. I hope that the feed change has made the difference and that the issues do not return in the spring - then I will have to figure out where to keep her with out the grass issues.
Thanks for all the advice.