On rock, alongside trail, near where the Purple and White trails connect.
Leaves ~1mm, sickle-lanceolate, long acuminate tip, minutely toothed on margins along length. Capsule ~1mm, red-black, plump, inclined, with yellow peristome teeth (cute!!!). Seta rough. Elongated cells in lamina and costa. Square alar cells. Costa ends past middle but before apex, similar in look to lamina.
Polytrichum commune var. uliginosum: elongate stems, tightly sheathing glossy leaf bases, leaves flexuose and recurved.
In this individual: marginal lamellae deeply notched to flat to rounded, lamellae 3-6 cells high
Genetic analysis suggests var. uliginosum is a separate lineage from var. commune:
https://onlinelibrary.wiley.com/doi/abs/10.1055/s-2000-5952
Growing unintentionally on artificial light, floating on a mass of rhizoids on water and attached to the intake filters in PetSmart fish tanks. Microscope photos show plantlets growing from gemmae, leaf shape, apical and axial gemmae with leaf primordia, and rhizoids. Plants strongly hydrophobic.
Found growing on disturbed soil next to a trail in the Great Swamp