A lot of thank-yous are in order for today’s entry. First of all, thank you to Wouter Bleeker of the Geological Survey of Canada for sending me today’s images via email. Wouter is responsible for the first two photographs, and his friend Mike Stubley is the photographer of the third. Also, thank-yous to local bryologists Terry McIntosh (speaker at next week’s Cedar Series Lecture) and Steve Joya for their attempts to identify these mosses without having samples in hand (identifying mosses from photographs is nearly impossible without a lot of close-up images). I’ll add one more thank-you in the last paragraph of this entry as well.

Since the identifications are tentative, today’s entry will instead be about the phenomenon shown in the images, on which Wouter wrote:

“For my field work I am up in the (sub)Arctic quite a bit, and here I attach some pictures of an interesting plant phenomenon: mobile moss or what we jokingly call “galloping moss”. These mosses are slowly creeping downhill, probably by daily frost-thaw cycles in spring and fall, and they seem perfectly happy with the movement. I have seen it in different moss species, including Sphagnum (not shown). Sometimes they stall out at a little crack or ridge, like in the first photo, only to start moving again after a while. If the hill side steepens, their leading edges may be overrun by the rest and things get a little messy, but otherwise all is fine. Some other species sometimes seem to catch a ride, as a small Saxifraga species in the second picture (upper right).”

“The most interesting aspect, perhaps, is that they leave this time-dependent trail from where they came, with the surface just vacated, bleached in the sun for 1-2 years or so, nice and clean; further back other algae and lichens slowly start growing back again. I don’t know the duration to full recolonization of the rock surface but this could be figured out and calibrated. It is probably on the order of 10-20 years. Just by coincidence, in the first two pictures the moss carpets are growing on stromatolitic limestone, formed by 1.9 billion year old cyanobacterial mats on a shallow, warmish, seafloor. These rocks are now exposed on the East Arm of Great Slave Lake, NWT. The third photo is from further north in the barren lands.”

Assuming the species identifications are correct, a few links: Grimmia ovalis (oval dry rock moss) and Niphotrichum ericoides in the Flora of North America, Niphotrichum ericoides (includes close-up photo) via the Natural History of Southeast Alaska, and Grimmia ovalis (with photographs) from the USDA PLANTS database.

On a different topic (and a different thank-you): my gratitude to Edmund Seow, Computer Systems Manager in the Faculty of Land and Food Systems here at UBC, for helping return Botany Photo of the Day (and the rest of the BG web site) back to normal. I think all issues are now resolved, and even though things will be changing again in April with the redesign of the entire UBC BG site, a problem-free web site for the next two months will be a huge relief.