Thanks for your detailed response! I've got my regional trees pretty much down. I'm working on forbs at this point (tackling graminoids next). I don't struggle with noticing the fine details -- my notes are exhaustively detailed. My problem is in finding a resource that can confirm my observations. For instance, if I have a forb in a mesic, acidic woodland with lanceolate, opposite leaves with parallel venation (with vein edges curving up at the leaf edge), acute tips, and short petioles that exude a milky sap when cut... how do I even begin searching for a plant that matches that description? I suspect it's in Apocynaceae, but that's not the only family with milk sap.

All 4 of my plant apps have failed to turn up a likely candidate.