Sounds like what you're looking for is a flora with dichotomous keys; something like Gleason & Cronquist's Manual of the Vascular Plants of the Northeastern United States and Adjacent Canada. In addition to the limitations you mention, an additional problem with field guides is that none of them contain all, or even most, plants that occur in an area. The best they can do is include most of the widespread, common species that you're likely to run into often. There are people who are either putting existing floras online or creating online floras. However, having spent some time doing it myself, let me assure you that it is indeed quite a lot of work. The online flora I've been working on (which will hopefully be finished in another couple of years) is at organmountainsflora.com. Other sources of online identification keys are plantsystematics.org (click the "keys" button at top left) and, although not nearly as sophisticated (being just a translation of written keys into html), Flora of North America. The FNA, when finished, will be the best authoritative source for plant identification in the US & Canada as a whole. Patrick

Looks like one of the Camphorweed, Heterotheca sp. Crushing the stems or leaves should produce a strong camphor-like odor, if that is it. Sometines called Golden Aster. Here's a website that has a number of Natives, by flower color and leaf arrangment, that you may find useful. Rb Here is a link that might be useful: Missouri Plants

I did a quick search for 'yellow wildflower' and found this great site at Colo State U with 22 pages of photos. I found several that had similar flowers and several with similar leaves, but none with both that I could tell. The leaf looks like a Rosemary in your photo, but I couldn't find anything in that category. The flower looks like Helianthus, but couldn't match the leaf. It's a lovely little plant, though. Good luck with your search. Here is a link that might be useful: Yellow wildflowers at CSU

You did it, fairy toadmother!! It most definitely is a corydalis, and the reason I wasn't seeing it as anything familiar in my books is due to the fact that only the pink variety was shown and that was a rather poor flower profile image without foliage. I looked at web pages of several different ones and corydalis flavula most closely resembles what I have here, although the range on that seems a bit off since it is listed for Connecticut and parts of the east. I will have to read more about this, but you definitely have given me an answer! Knew I could count on you forumers! Thanks!