Field of Science

The Hairy Cap

Based on a request from last week, I have posted a photo of the hairy cap of Polytrichum commune. The technical name for this cap or hood is a calyptra (plural=calyptrae). It typically sits atop the moss sporophyte and covers the capsule. This highly hairy hood (try saying that 3 times fast) is a characteristic that is shared by members of the genus Polytrichum. Calyptrae may be found year round, but are most prevalent during the late summer and early fall in Polytrichum commune. The stalk, capsule and calyptra are attached atop the leafy portion of the moss. Check out the post from October 8th and imagine the structures shown today growing out of the apex of the leafy plant. If you have located the hairy calyptra you have found a Polytrichum.


  1. I just read about an effort to recreate (virtually) the world that used to lie where New York now stands "down to the varieties of moss". Made me wonder what mosses would have been where Torrey stood way back when .....

  2. I bet that the moss flora would have been great! I can imagine old growth trees that would have provided good habitat for mosses that grow on bark. Based on the forests of Connecticut I would also imagine that there would be a fair number of rocks throughout the forest, which would provide an additional mossy habitat. Mosses and lichens are pretty sensitive to pollution as well. Without many people and the pollution that we produce the number of species growing in our area would probably be much higher.
    Additionally I am interested to know where you read about the virtual re-creation of New York.

    (FYI - Torrey is the name of one of the biology buildings here at the University of Connecticut. The George Safford Torrey Life Sciences Building)

  3. It was in the New Yorker (1st Oct issue) - about a Wildlife Conservation Society project.


Markup Key:
- <b>bold</b> = bold
- <i>italic</i> = italic
- <a href="">FoS</a> = FoS