Polytrichum piliferum
- A photographic image.
- http://www.helsinki.fi/~korpela/polytrichum_piliferum.html

Polytrichum ohioense
- Photographs of the gametophyte and a microscopic image of a leaf tip and capsule.
- http://vis-pc.plantbio.ohiou.edu/moss/Polytrichum.html

Polytrichum juniperinum
- Description and good photographic images of this species which has a worldwide distribution.
- http://www-biol.paisley.ac.uk/bioref/Bryophyta/Polytrichum_juniperinum.html

Polytrichum commune
- A photographic image.
- http://www.helsinki.fi/~korpela/polytrichum_commune.html

Polytrichum
- Photograph of gametophytes and sporophytes.
- http://botit.botany.wisc.edu/images/130/Bryophytes/Bryophyta/Hairy_cap_moss/Polytrichum_.html

Polytrichales
- A description of the order.
- http://home.manhattan.edu/~frances.cardillo/plants/nonvas/poly.html

Operculum
- Photograph of an operculum of a Polytrichum species.
- http://botit.botany.wisc.edu/images/130/Bryophytes/Bryophyta/Hairy_cap_moss/Polytrichum_operculum_.html

Hairy Cap Moss
- Photographs of Polytrichum species.
- http://botit.botany.wisc.edu/images/130/Bryophytes/Bryophyta/Hairy_cap_moss/

Genus Polytrichum (Haircaps)
- Photographic images of this easily identified moss.
- http://www.perspective.com/nature/plantae/polytrichum.html

Atrichum oerstedianum
- A photograph showing two shoots, one hydrated and one curled up and dry.
- http://www.science.siu.edu/landplants/Bryophyta/images/Atrichum.oerst.JPEG

Antheridia
- An image of male Polytrichum plants.
- http://botit.botany.wisc.edu/images/130/Bryophytes/Bryophyta/Hairy_cap_moss/Male_MC.html

Family Polytrichaceae
- Photographic images of several genera, including Dawsonia superba, the world’s tallest moss.
- http://www.hiddenforest.co.nz/bryophytes/mosses/familys/polytrichaceae/polytrichaceae.htm