Pogonatum urnigerum is a species of moss in the family Polytrichaceae, commonly called urn haircap.

[3] It can be found on gravelly banks or similar habitats and can be identified by the blue tinge to the overall green colour.

[4] It is an acrocarpous moss that grows vertically with an archegonium borne at the top of each fertilized female gametophyte shoot which develops an erect sporophyte.

[6] This species of moss is known to live in many locations across Europe and North America such as in: Greenland, Iceland, Canada, and the United States.

[7] In Asia, Pogonatum urnigerum has been found in Japan, China, Korea, Mongolia, India, Himalayas, Philippines, and Papua New Guinea.

This part of the life cycle consists of protonema (the preliminary stage where the propagule develops green thread-like filaments), the rhizoids (filaments growing beneath the bryophyte that help anchor the bryophyte to its substratum), the stem, the leaves, its reproductive structure (archegonium in female plants, antheridium in male plants), and the calyptra (a thin tissue that forms from the venter of an archegonium and protects the sporangium as it develops).

The sporangium has an operculum, epiphragm, columella, sporangial jacket, a spore bearing layer, and nematodontous teeth.

[10] Although nematodontous teeth are not hygroscopic,[11] they may aid in spore dispersal through small movements (they do not move much).

At maturation, the sporangium measures approximately 2-3mm in length, is cylindrically shaped, and light brown to red-brown in colour.

The first stage of protonema is chloronema which consists of irregular branching, transverse crosswalls, round chloroplasts, and no budding.

Once an egg has been fertilized, it develops a diploid sporophyte structure which is composed of a foot, seta, sporangium, and operculum.

Annual growth increments can be found on the stem of this species of moss that resemble the rings of trees.

When an egg in the archegonium of a female Pogonatum urnigerum shoot is fertilized, it matures and develops the sporophyte structure of the plant which sexually reproduces by producing and dispersing spores.

[15] Mosses belonging to the class of Polytrichopsida are known for several defining characteristics such as stem leaves with unistratose lamina, numerous lamellae, a costa, stereids, guide cells, and hydroids.

This class is also well known for a hairy calyptra that is present in many Polytrichopsida mosses which functions to protect the developing sporangium.

[16] The leaves of Pogonatum mosses are generally erect and are shaped lanceolate from mid-leaf to the tip and have a wider base.

[12] The sporangia of mosses belonging to this genus do not have stomata, they have thirty-two peristome teeth that are composed of entire cells and a hairy calyptra.