One of the quite wonderful Lycopods (as they used to get called before much more work on their classification happened which re-arranged many spp. in different genera. These do remain still in the botanical family: Lycopodiaceae. ).
I need to look into the botanical key (again), and check the latest botanical name .
_Selaginella uliginosa_ has less tall, less clustered branches, with not so densely packed leaves..
And does not identify to _Pseudolycopodium densum_ (synonym: _Lycopodium deuterodensum_ ) .