Maybe you can compare with Desmodium paniculatum on Discover Life Christine, there's a lot of photos showing all parts including the different leaf shapes.
http://www.discoverlife.org/mp...
There's a list of species .. (you will have to search again for Desmodium!)
http://www.discoverlife.org/20...
USDA maps showing locations ..
http://plants.usda.gov/java/pr...
