I hesitated to answer when your first message came through, as I have no
specific information on what CPs grow in Minnesota. However, your climate
(at least in the lake region) is similar to ours here in Quebec and so I
think you could safely presume that the pitcher plant mentioned, as pointed
out by Chris Teichreb, Sarracenia purpurea (he suggests the northern
subspecies S. purpurea purpurea, but I'm not a botanist and couldn't
confirm that) is the one. It is the only pitcher plant I can imagine
growing in your climate and, considering it is found all across Eastern
North America (and I think your Lakes district would fall into that), I
would actually be surprised if it wasn't grow somewhere in your state.
Other wild carnivorous plants growing in Quebec (and which ought to be in
Minnesota as well) include several Drosera species (D. rotundifolia seems
particularly abundant in peat bogs and on moist sand and rocks), Pinguicula
(P. vulgaris, but it is hardly common here and is apparently found on moist
rocks) and various and sundry Utricularia, most of which are aquatic and
some of which are subterranean. The only Utricularia I've ever seen (I
don't usually go around sticking my head underwater to look for plants) was
one which sprouted all on its own in my half-barrel water garden, having
come from who know where.
Good luck in your research!
Larry Hodgson
Sainte-Foy, Quebec