Ground pine. Nice big patch I'd somehow overlooked. This is common in Pennsylvania as a whole, but I've never seen it just over the line in the Delaware Piedmont; it doesn't do well where there are earthworms. (Very common on the Coastal Plain, though.)
Shining clubmoss. If you look closely, you'll see that this is sprouting from a gemma! Saw about five young shoots around this size in the immediate vicinity, on a steep oak-heath slope bare of leaf litter. I checked upslope and there were no colonies, so it's not clear where the gemmae dispersed from.
In sphagnum bog
Leaves in horizontal plane. ..one side with much shorter leaves.
Growing on the beech forest floor.
Lycopodiopsida is a class of plants often loosely grouped as the fern allies. Traditionally the group included not only the clubmosses and firmosses, but also the spikemosses (Selaginella and relatives) and the quillworts (Isoetes and relatives). However, the latter are now usually separated off into a separate class, Isoetopsida.