Numerous Plant Quizzes - Annotated Photo

I recently posted the following photograph from Round Lake in Starke County, Indiana as a plant quiz and asked for identification of as many species as possible.


I've labeled the plants that I was able to ID from the photo and my memory of the site. You'll probably need to click on the photo to expand it to see the answers and the plants they are denoting. The key to the answers is below...

A – Solidago graminifolia v. nuttallii (Euthamia graminifolia)
B – Scirpus pungens (Schoenoplectus pungens)
C – Pycnanthemum virginianum
D – Eupatorium maculatum (Eupatoriadelphus maculatus)
E – Potentilla fruticosa (Dasiphora fruticosa)
F – Lysimachia quadriflora
G – Dryopteris thelypteris v. pubescens (Thelypteris palustris v. pubescens)
H – Rosa palustris?
I – Juncus dudleyi
J – Calamagrostis canadensis?
K – Eupatorium perfoliatum
L – Aster novae-angliae
M – Solidago riddellii (Oligoneuron riddellii)
N – Carex sterilis
O – Typha sp.

I don't see Onoclea sensibilis, Carex brunnescens (maybe this was guessed for Carex sterilis?), or Rudbeckia hirta (maybe this was guessed for the yellow composite in the background, which I think may be a Helianthus?), which were all suggested.

Pretty sharp group we have here! There were very few plants that I was able to identify from the photo and my memory of the site that were not identified by the group. Thanks for all of your comments.