Winter Mosses (2009-2010)

Every winter, as the cold grip of dormancy overtakes our vascular flora, my attention is turned from phanerogams to cryptogams: bryophytes to be specific. While I am still a fogged in amateur, I am starting to hear voices in the mist. I’m seeing patterns and struggling less. Here is an example of how tricky moss identification can be. The two moss specimens below were collected from the margin of my driveway.

Accustomed to the macroscopic, my eyes failed to pick up on the subtly dramatic differences. What I assumed to be one “thing” was indeed two, each as evolutionarily relevant as a Blue Whale or a Dawn Redwood. Here is a closer look.

The specimen on the left is Weissia controversa. Barbula unguiculata is on the right (they are reversed in the first photo). Notice how much narrower the leaves of Weissia are compared to those of Barbula. The capsules of Weissia are also shorter. Having trouble seeing the leaf differences? Here they are after being wetted.

Both species are abundant throughout the Midwest and common in dry habitats on soil or occasionally rock.

Here are some photos of other mosses I encountered this winter that are common enough to keep an eye out for.

Ceratodon purpureus - on soil or base of trees; common. Can be readily identified by the densely tufted habit and the red-purple setae (stalks of the capsules). Notice how the tuft makes a green, tan, purple rainbow in longitudinal section.
Fissidens bushii - on soil in fields, glades and prairies; common. Reputed to be a calciphile. The genus Fissidens is pretty distinct in having strongly distichous stems.
Funaria hygrometrica - on disturbed soil especially burned areas; common. Plants can occur singly or in sparse colonies but not in tufts. The asymmetrical capsule distiguishes Funaria from similar genera such as Pohlia and Bryum.
Mnium affine -on soil in forests; common. One of the widest leaved Mnium species. Leaves with singly serrate margins that are serrate to the base. Recently placed in the genus Plagiomnium. But since I don't know why, I'm sticking with Mnium.
Physcomitrium pyriforme - on soil; weedy and common. Its spherical capsules make it very distinct.
Polytrichum commune - on dry acidic soil in woodlands and glades; common. Leaves are toothed and have reddish tips.
Thelia asprella - on the base of trees in mesic to dry woodlands and forests; common. Forms thick mats from extensive rhizomatous branches. Leaves are ornately papillose.
Thelia lescurii - on soil in fields and open woodlands; common. Much less branched and very low to the ground
At this rate I might be a decent field bryologist by the time I'm 200 years old. Regardless, I'm enjoying the challenge and gaining appreciation for the great and small of our natural world. Nothing can be more rewarding or humbling.


  1. Mosses - so beautiful to look at, so difficult to know.

  2. Can you share any good Missouri-specific references?

  3. Excellent...thanks for tying them to the communities.

  4. Justin - I think that your photos look great. It is amazing the moss diversity that can be found in the backyard.
    As to your comment about the Plagiomnium/Mnium debate, it depends on who you talk to. Crum and Anderson's Mosses of Eastern NA recognizes both but I know that I have seen them all lumped into Mnium in other publications. The main morphological difference is that Plagiomnium has single teeth along the margin and Mnium has double teeth sticking out in pairs from the leaf edge. I think that it is easy enough to tell whether or not there are teeth in the field, but telling double from single with a handlens can be a challenge.
    Cheers - Jessica

  5. Lee,

    There may be others but the only Missouri-specific reference I know of is "Mosses of the Interior Highlands" by Paul Redfern. It is a picture-less, technical guide that is best used in conjunction with other books. There is also the "Walk Softly" book that is supposed to be a field guide to MO mosses and lichens. It is full of misprints and misidentifications. It is also so incomplete that it is useless. Even more than vascular plants, mosses are understudied and under appreciated.

  6. Hi Jessica,

    I've wondered what you've been up to since Miami. Great things, it turns out. Your blog ( is phenomenal. I have already spent a good hour reading your articles and following your links. I'm sure to be a frequent visitor.

    Thanks for clarifying Mnium/Plagiomnium for me. Seems like a classic "six of one..." situation.

    All the best-Justin

  7. This post is inspiring! Great shots and descriptions!

  8. Thanks! I have a stockpile of mosses I've learned and photographed since this post. Perhaps it is time for part two.


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