Reindeer lichen is so called because it bears a certain resemblance to reindeer antlers.
A few miles north of Frederick, Md., Deborah Landau is leading me down a forested slope in the Catoctin Mountains.
It's cold — little more than 10 degrees Fahrenheit — but as we scamper down through the trees, it's clear not everything is frozen. There's water, bubbling up out of the ground, from under rocks and at the bases of trees.
"It's coming from out of the mountain, and this is where this stream is starting — it's beautiful," Landau says.
A wealth of lichen
The stream is beautiful, but we're in search of something a little more colorful; some green amidst all the brown and white of winter.
Landau is a biologist with the Nature Conservancy, a non-profit that owns the preserve in which we're hiking. She's promised me green, and as we scale the hill on the other side of the stream, the full spectrum appears to carpet the rocks underfoot.
"We have a really wide range," she says. "What you see here is this really soft carpet is called sphagnum moss. We also have some interesting lichens, some of them are called rock lettuce that presumably you can eat, but I've never tasted one."
There's also a bushier pale green variety, known as "reindeer" lichen for its antler-like appearance. Other types of lichen here look almost pinkish.
"You have the entire palette of greens," Landau says. "You have the vibrant greens and the pale greens. You have the nice soft fuzzy ones and the ones hugging on the rocks."
Winter survivors still thrive
These organisms have a few tricks for thriving in winter when others flora and fauna hibernate or die off.
Rock lettuce isn't likely to make it on to a menu near you any time soon.
"This plant grows very low to the ground, and it has its little microclimate between the rocks. We're facing south so it's taking advantage of all the warmth and all the sunlight it gets during the day," Landau says.
Many also have the ability to go dormant when it gets too cold, and regain their lushness with a single day of more moderate temperatures.
Landau says the Nature Conservancy targeted this land because of the diversity of plants on rocky outcroppings like this one, and that diversity has practical applications for everyone in our region.
"Having a healthy, rich, diverse system that is working with all the different component parts translates into clean air, and the clean water that we so desperately need," Landau says.
Clean air, clean water, and rock lettuce to eat. A little warmer and I could survive for weeks out here.
Actually, she said this stuff was edible, not palatable.
The other name for rock lettuce? Rock Tripe.
[Correction: A previous version of this story incorrectly indentified biologist Deborah Landau as Deborah Solomon. We apologize for the mistake.]
What's the coolest thing you've ever seen while hiking in the winter? And have you ever eaten rock lettuce? You can let us know how it tastes on twitter — our handle is @wamumetro — or email us at firstname.lastname@example.org.
[Music: "I've Got My Love To Keep Me Warm" by Les Brown & His Orchestra from Great Swing Classics in Hi-Fi / "We Need Some Money (Bout Money)" by Chuck Brown from Anthology of Go-Go: Non Stop Mix by DJ Cash Money ]