Not sure what your native Selaginella sp. is, but the native Minnesota S. rupestris that I have seen grows in pure sand of stablized dunes.

Rick

Thanks Rick for the information.
I am interested to learn if anyone else besides myself and a few others who I know are growing any of the different species and how they are doing so.
Your information is important and I will quote it when I start working on a Species Profile Page for the flora I am currently working on.

Do these stabilized dunes have an early melt off of snow or any snow accumulation at all? I am presuming that the species is on dunes inland from the freshwater shores.
If you ever have a chance to visit them hope you have a digital and take some images. Get general habitat, close up of the colony, and a closer up of a plant. Post to a photo sharing site and send me the link and I will include it in the flora.

All I have right now is this one, which you are free to use for non-commercial purposes. Unfortunately, it is dumbed down to 237KB, but if you're interested drop me an email through GW and I can send you the file. I seemed to have misplaced my original photos, but I do have more. I'll keep looking.

Photo taken at Uncas Dunes Scientific and Natural Area, near Zimmerman, Minnesota. In this particular area, the ground was dominated by mosses and lichens, from memory I estimate 70% coverage, the rest exposed sand, and interspersed with 10-15ft. native Juniperus virginiana that give significant shade.

Thanks for sharing. It is definitely Selaginella rupestris. An email is on its way!!!