When I visited the EzTreeSee website at http://eztreesee.coli.uni-saarland.de/ and entered "Mary had a little lamb," I immediately encountered abbreviations that I had never seen before, to wit...
NNP VBD JJ NN
I've searched the net in vain for the meanings of these abbreviations. But that doesn't mean that there isn't a link.
So where can I find a list of abbreviations for the names of constituents identified in phrase-structure grammar trees?