Lest we become completely overwhelmed and demoralized by horrendous events happening around the world, the news media have also been reporting, as they usually do around the holidays, on the benefits of gratitude. According to one article I read, recent studies show that expressing gratitude will improve heart health and help us live longer. Or was that coffee? Either way I’m all for it. I read another article suggesting to those of us without the glass-is-half-full gene, which is a “mutation,” according to the author, that we might start our journey along the path to happiness with baby steps. Be grateful for the little things.

Like lichen. I hardly ever notice lichen in the dry summer months when it’s dormant and obscured by foliage. Now that we’ve had some rain, and more light is reaching stems and trunks and rock walls, the lichen is waking up and promising to offer a few extra colors to embellish winter’s monochrome. Some of what grows on stone is orange and yellow, while most of the tree-dwelling lichen is a dull grey green that glows a brighter sea foam or deepens to moss on dark and damp days. It takes the form of lacy speckles, flat rounded patches that flake like lead paint, and fuzzy tufts of reindeer moss that litter the sidewalks after a good wind.

Despite appearances to the contrary, lichen does no harm. It’s a passenger, not a parasitic devourer of tree flesh. And “it” is actually two things, a fungus and an alga, a dynamic duo, in a symbiotic relationship. The fungus provides support by hitching a ride on bark, rocks, and anything else that stays put long enough for it to grow at a snail’s pace, and collects moisture and minerals from the air. The alga uses the moisture and nutrients in its work to convert sunlight into food it subsequently passes back to its partner. And together, aside from being beautiful in the eye of this beholder, they provide sustenance for insects and animals, nesting material for birds, and when it sloughs off, nitrogen for the soil. Because pollution restricts lichen’s growth, it is an excellent gauge of decent air quality too.

The presence of lacy lichen undergarments on your trees and shrubs is an indicator of slow growth: plants that hold onto their bark for a while before shedding it offer lichen an opportunity not unlike rent control. Most trees grow more slowly as they age, and others are naturally slow even in their youth; lichen on their limbs is no cause for alarm. On the other hand, an abundance of lichen on an otherwise fast growing species can signal compromised health, such as root stress perhaps due to soil compaction or flooding. We gardeners should be grateful for the message even if some of us aren’t inclined to appreciate the messenger.

I am. My paths towards happiness—the one around my garden, and the one I take over the river and through the woods—are festooned in lichen. It will be a sight for my winter-sore and color-starved eyes, and serves as a reminder to breathe deeply. It’s one of the little things I’m going to remember to feel grateful for.

Kristin Green is a Bristol-based gardener and author of 'Plantiful: Start Small, Grow Big with 150 Plants that Spread, Self-Sow, and Overwinter'. Follow her blog at trenchmanicure.com.