Stereodon cupressiformis (Hedwig) Mitten

Plants small to large, rusty green, golden green, yellow-green, or pale green. Stems 1-8+ cm, pale to yellowish green, brown with age, creeping to erect, , irregularly pinnate to nearly unbranched, attached shoots often regularly pinnate, branches 1-3 cm; hyalodermis absent, central strand poorly developed; pseudoparaphyllia filamentous, 1-3-seriate at base. Leaves , not to decidedly falcate-secund, ovate to oblong-lanceolate, gradually or abruptly narrowed to apex, 1.5-2 × 0.5-0.8 mm; base not decurrent, not auriculate; margins recurved to plane proximally, serrulate (sometimes weakly) distally, occasionally nearly entire; acumen slender; costa double and short or obscure; alar region well defined, basalmost cells larger, sometimes hyaline, yellowish or brownish; basal laminal cells shorter, wider than medial cells, not pigmented, walls not pitted; medial cells (50-) 60-80 × 3-4(-5) µm. Sexual condition dioicous; . Seta reddish, 1-2.5(-3) cm. Capsule slightly inclined, reddish, cylindric, 1.8-2.5(-2.8) mm; annulus 1-3-seriate; operculum conic to rostrate; endostome cilia 1-2(-3).

Varieties 9 (4 in the flora): nearly worldwide, except Antarctica.

Hypnum cupressiforme is an extremely polymorphic species, reflected in the more than 60 varieties that have been described. The species has a wide ecological amplitude as well as a nearly cosmopolitan distribution and is found in all climatic regions except the Antarctic. Taxonomic features reliable in most other species of Hypnum are plastic in H. cupressiforme. Within a single clone, it is possible to sort out several named varieties. Variety lacunosum Bridel was noted by H. Ando (1989) to be weakly differentiated in North America, and he tentatively cited specimens from Nova Scotia, Newfoundland, and South Dakota. Ando noted that var. lacunosum typically is robust, thick-complanate to julaceous, with leaves almost straight to weakly falcate and abruptly narrowed to a short acumen, but the North American material is not robust and is therefore problematic.