Plants rusty green, golden green, yellow-green to pale green, medium sized to small, 2--10 cm, occasionally longer, prostrate to suberect. Stems pale to yellowish green, brown with age, epidermal cells not hyalodermous, central strand poorly developed, irregularly pinnate to nearly unbranched, shoots, attached shoots often regularly pinnate; pseudoparaphyllia filamentous, 1--3-seriate at base, but ending in elongated pointed 1-seriate tip. Leaves weakly to decidedly falcate-secund, ovate to oblong-lanceolate, generally gradually curved to insertion and tapered to a slender acumen, 1.5--2 × 0.5--0.8 mm, margins serrulate (sometimes weakly) in distal half, occasionally nearly entire, recurved to plane proximally; costa double and short to obscure; median cells (50--)60--80 × 3--4(5) µm; basal cells shorter and wider; alar regions weakly or not excavate, made up of a well-defined triangular to quadrate area of many subquadrate cells or reduced to very few quadrate cells (sometimes pigmented), the more basal cells larger, sometimes hyaline, yellowish or brownish. Sexual condition dioicous; inner perichaetial leaves erect, oblong-lanceolate, serrulate distally, not plicate; margins plane; costa obscure. Seta reddish brown, 1--2.5(--3) cm. Capsule reddish brown, slightly inclined, cylindric and slightly curved, 1.8--2.5(--2.8) mm, excluding conic to rostrate operculum, annulus 1--3-seriate; cilia of endostome usually 1--2(--3).

Varieties 9 in the world (4 in the flora): Cosmopolitan; absent in Antarctica.

Hypnum cupressiforme is an extremely polymorphic species, reflected in the more than 60 varieties that have been described. It has a wide ecological amplitude as well as a cosmopolitan world distribution and is found in all climatic regions. 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. Hypnum cupressiforme var. lacunosum Bridel was noted by H. Ando (1989) to be weakly differentiated in North America, and tentatively cited specimens from Nova Scotia, Newfoundland, and South Dakota. Ando noted that the 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.

Lower Taxa

• Hypnum cupressiforme var. cupressiforme
• Hypnum cupressiforme var. filiforme Bridel
• Hypnum cupressiforme var. julaceum Bridel
• Hypnum cupressiforme var. subjulacuum Molendo