Field of Science

The Tree Moss Climacium

This is a really cool moss that often grows in seepy, shady areas next to standing pools of water or streams. It's common name, tree moss, comes from the growth form of its leafy gametophyte, which resembling a tiny tree. Due to its tree-like appearance these plants have been used as the trees in model train displays. I have also heard that they were used as decorations in ladies hats.
Shown here is the species Climacium dendroides. I took some photos and wanted to share them because this is the first time that I have seen this species with sporophytes, and thus the first time that I have seen their calyptrae.

The calyptra (shown on the left) is pale yellow, smooth, and cucullate (splitting up a single side upon capsule expansion). I wanted to section some of them to look at their cuticle, but I lost this one. Then when I went back to the population that was collected for DNA extraction in the lab I found that all the calyptrae and sporophytes had already been used for a massive DNA extraction. Too bad. It would have been cool to get a look at their calyptrae using the electron microscope. 

A really spectacular feature of the sporophytes are their peristome teeth! The exostome (outer ring of teeth) are deep brown-red in color. They contrast well with the endostome (inner ring of segments) that are golden brown. The inner teeth are longer and when dry the outer teeth curve inward, as shown in the image below.

The genus name Climacium, comes from the Greek word klimax, which means ladder. The researchers who named this genus thought that the endostome had the appearance of a ladder. I think that it is a pretty accurate description. However, one would have to be tardigrade-sized to use them as a ladder!

Keep an eye peeled for this species if you are in deciduous forests that have some wet areas. I see the gametophytes regularly in Connecticut and seeing some sporophytes is definitely a treat!


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