Ptilium crista-castrensis is a moss species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 within the family Hypnaceae

Hypnaceae

Hypnaceae is a large family of moss with broad worldwide occurrence. in the class Bryopsida, subclass Bryidae and order Hypnales. Genera include Hypnum and Ptilium.-Ecology:...

, in the class Bryopsida

Bryopsida

The Bryopsida constitute the largest class of mosses, containing 95% of all moss species. It consists of approximately 11,500 species, common throughout the whole world....

, subclass Bryidae

Bryidae

Bryidae is an important subclass of Bryopsida. It is common throughout the whole world. Members have a double peristome with alternating tooth segments.-Classification:The classification of the Bryidae.Superorder: Bryanae...

 and order Hypnales

Hypnales

Hypnales is an order of moss.-Classification:...

.

Ecology

This species occurs on the floor of Canadian boreal forests as well as many forests of northern Europe; an example of this occurrence is within the Black Spruce

Black Spruce

Picea mariana is a species of spruce native to northern North America, from Newfoundland west to Alaska, and south to northern New York, Minnesota and central British Columbia...

/Feathermoss climax forest

Climax community

In ecology, a climax community, or climatic climax community, is a biological community of plants and animals which, through the process of ecological succession — the development of vegetation in an area over time — has reached a steady state. This equilibrium occurs because the climax community...

, often having moderately dense canopy and featuring a forest floor of feathermosses including Hylocomium splendens

Hylocomium splendens

Hylocomium splendens, commonly known as Glittering Wood-moss, Stair-step Moss and Mountain Fern Moss, is a perennial clonal moss with a widespread distribution in Northern Hemisphere boreal forests. It is commonly found in Europe, Russia, Alaska and Canada, where it is often the most abundant moss...

, Pleurozium schreberi and Ptilium crista-castrensis.