Lycopodium is the genus. I cheated though. Hover over this image with your mouse on her website and you will see. I will try to pinpoint the exact species.

The more I look at it, the more I think it actually might be a member of the Selaginella genus (another clubmoss genus).

Compare with Selaginella kraussiana, which looks very similar to the picture.

Here is a pic of Selaginella kraussiana 'Frosty Fern.'

Thanks, Scott. Shoot - I should have hovered over the image. I thought it was a very, very low ground cover. But looking at your two IDs is making rethink what I thought I was seeing in this picture. Again, thank you.

I am fairly confident it is a Salaginella (commonly called Spikemoss) of some sort (perhaps Peacock Moss, S. uncinata). They are in the class Lycopodiopsida and were perhaps once classified in the genus Lycopodium (hence the Lycopodium reference).They are fern allies but not true ferns though they do not produce flowers and reproduce with spores. Very ancient and fascinating plants. They are purportedly hardy to Zone 7 and need little sun but a great deal of moisture. They are usually sold as terrarium plants in nursery greenhouses.

Here is a link that might be useful: Peacock Moss

Another possibility that came to mind is Miniature Brass Buttons (Leptinella gruveri), but the detail of that picture makes it pretty hard to tell.

I think you are right about it being Peacock Moss -- and I'm a big fan. I have found that most tiny leafed ground cover seems to be listed as sun/part sun. And I've got quite a bit of shade. I also wouldn't have thought to look in the terrarium -- great advice. Thank you!

I think I have finally put this to rest based on the picture below at the attached website: It does appear to be Selaginella kraussiana 'Aurea' which is the most commonly available species and cultivar in nurseries. I actually have one that I keep as a houseplant. They work outside too (reportedly evergreen in Zone 7) but have to be kept moist, which can be challenging during hot Mid-Atlantic summers, even in full shade.

Peacock Moss (Selaginella uncinata) is fairly fast-spreading, so if you have a large area to cover in the shade, it can be used as a shade lawn, though again moisture can be a challenge.

Here is a link that might be useful: Selaginella kraussiana