In late fall and winter when most plants are dormant, lichens are still growing. You have probably noticed lichens on trees, rocks and even tombstones. Lichens can survive and grow in conditions of extreme cold and dryness, even in parts of Antarctica.
Lichens are a curious combination of a green algae and a fungus. They live in symbiosis, to the mutual benefit of both. The fungus gives the lichen its shape and structure. It slowly dissolves its host, usually tree bark or rock. It does this, harmlessly, to provide minerals to itself and to the algae. Whenever there is light and enough moisture, the algae photosynthesizes. This provides food in the form of sugar both to the lichen and to the fungus. I was taught a little ditty to remember what lichens are made of: Alice algae and Freddy fungus took a “lichen” to each other.
Lichens are pioneer life forms, and very ancient in origin. Robin Wall Kimmerer in her lovely book Braiding Sweetgrass states, “Umbilicaria [one of our northeastern lichens] is known to be among the first to colonize post-glacial forelands today, just as it did when the earth was raw and bare, ten thousand years ago–another era of great climate change.”
Lichens grow very slowly and live for many decades. Lichenologist Richard Weaver, writing in the publication Arnoldia in 1975, states that lichens only grow in areas where there is very little air pollution. In cities, lichens absorb sulphur dioxide and other air-borne chemicals, which kill the lichen. The closer one lives to the city the fewer lichens one sees. Weaver states that one can find very few lichens in Boston, even in the Arnold Arboretum.
Lichens are divided into three main types: Crustose, which form a crust on bark or rock, Foliose, which resemble leaves, and Fruticose in which the lichen has a shrubby look (examples are British Soldiers, Reindeer lichen, and Old Man’s Beard).
Foliose lichens are the most familiar type that we see on tree trunks and rocks everywhere in Westford. Several species grow in leafy round patches. They can reproduce vegetatively (broken pieces reproduce on a new surface} or by wind-blown spores. Another type, less common in Westford, is called Umbilicaria . There are at least twenty-four species of Umbilicaria in the eastern United States. Wikipedia identifies ours in the northeast as Umbilicaria mammulata. These lichens thrive at higher elevation. In Westford I see them on rocks on the Sassafras Trail in the North Hill area. They resemble burnt potato chips stuck to the sides of rocks. Their edges are loose and the lichen is attached to the rock only by the middle or as their Latin name implies, by their “belly button”. Umbilicaria can range in size from that of a pencil eraser to one or two feet in diameter. When dry, they curl up, go dormant, and look black and dead. When wet they unfurl, turn green and start growing. A fun trick to try is to pour a little water from a water bottle on some of these lichens when they are dry and watch them almost instantly open up and turn green. This amazing habit allows them to photosynthesize whenever conditions are right.
Umbilicaria is edible, but not very appetizing because it is high in tannin. It can be boiled with many water changes, and eventually will make a broth containing chewy lichens. It is said to be good survival food. This is the origin of its common name, “Rock Tripe”. Now that our spectacular fall foliage is over, maybe you can go out in Westford’s clean air and see how many types of lichens you can find.
Many thanks to all flora and fauna reporters for the month of November. Please send reports by December 26 for inclusion in the next Westford Wildlife column. You can call me at 978-692-3907, write to me at 7A Old Colony Drive, or e-mail me at firstname.lastname@example.org.
Late October Reports:
Ginger Dries, Sherwood Drive. October 5, a red fox and seven turkeys in yard. October 11, Carolina wren. October 10 and 24, black bear visited at the feeder near the house. October 28, first junco at feeder.
Marian Harman, at trolley line north side of East Boston Camps. October 29, large flock of robins (50 or more) in the trees, sparrows, cardinals, jays, woodpeckers, crows, a raven overhead. Two waterfowl doing lots of feather ruffling and making plaintive calls in the reeds (probably wood ducks). Lovely muted colors in the foliage, bright red winterberry in swamp. On Pilgrim Village trails. October 30, 57 degrees and drizzly. Six mallards, four brilliant males and two lovely females, paddling quietly on Keyes Pond. A beautiful healthy-looking red fox walking quietly through the forest. It walked along a log, stopped to look at me. It blended perfectly with the reddish oak leaves–made my day. A special gift on a dreary day. Lots of tiny flies with blue and white abdomens helicoptering around. I tried to catch one to have a better look at it, but couldn’t. When I got home I looked them up and found they are wooly aphid adults which grow wings in the fall in order to search out wintering spots.
Mary Downing, Lane’s End, near Hildreth Hills. Two years ago, saw a mountain lion leap across her yard. It had huge paws, was long and had a long tail.
Rosemarie Koester, Providence Rd. October Report: Our two bird baths are being used frequently. Lots of goldfinches, house finches and purple finches. A pair of cardinals, blue jays, a few doves, a few grackles, chickadees, numerous sparrows, several woodpeckers. Chipmunks, a few squirrels, rabbit, spiders around the house and garage, chipmunks came on deck and dug in flower pots. Mushrooms on old birch stump and Indian pipes. Heard a group of coyotes. A bear came through the yard again last week. He left the metal bird feeder on the ground and missed the goldfinch feeder. “They must be in a hurry to eat a lot before hibernating.” We have a ton of acorns from our oak tree in front.
Rich Strazdas, Villanova Drive. October 30, saw a beautiful bird on my bedroom air conditioner this morning–a starling in winter plumage [Rich sent photo-MH] They were foraging in my dormant veggie garden. “Who knew winter starts in October?”
Marian Harman, at Pilgrim Village. November 2, 30’s, sunny, beautiful. A pair of buffleheads resting on Keyes Pond in full breeding plumage–a lovely surprise. Ten mallards took off from Snake Meadow Brook. November 3, great blue heron standing in swamp by lake. Later, blue jays chasing a large, bulky very dark hawk, maybe a dark red-tail. November 7, otter scat near the pond (has fish scales in it). I smelled the light skunky smell of fox urine on the trails. Picked up a tick. November 8, first junco here, first white-throated sparrows here, first light snow. On Forge Pond, twenty-six mallards and five geese. November 10, a walk on Pilgrim Village trails. Surprisingly, the lady ferns are still bright green. A skim coat of ice on the brook. November 23, on Littleton Rd., mockingbird in swamp, and great blue heron overhead. Five mallards on Keyes Pond. lovely sweet fall smell of oak leave underfoot. Lots of foliose lichen on tree trunks. At the feeder, four chickadees, six white-throated sparrows, juncos, white breasted nuthatch, two downy woodpeckers, three doves, jays, two crows, four goldfinches, two female cardinals. November 23, a walk on Lowell Rd. Frances Hill Conservation land: Red-tailed hawk being chased by blue jays, two red-bellied woodpeckers, chickadees, titmice, downy woodpeckers. At 9 pm tonight, we heard our squirrel baffle clanging on the deck, and looked out into the dark. An animal jumped down, taking the suet with it, but leaving the basket on the deck. We couldn’t see the animal well–seemed large, but too small for a bear. Maybe a raccoon or a fisher.
Debbie Prato, Hayrick Lane. November 4, first junco, Carolina wren, purple finches, white-throated sparrows, Canada geese, twenty young turkeys swarm into the yard twice a day. November 25, we finally got a bear in this area.
Margaret Wheeler, Depot St., November 6. Two bucks in the narrow strip of woods between us and our neighbors on Churchill Court. When I started driving down our driveway, one of the bucks turned and watched me while I lowered my car window and took a picture. In the evening, Mark checked his game camera and found a video of a doe trotting from behind the garage towards the neighbor’s house, followed by a buck. [Margret sent a great video-MH] November 13, Mark’s game camera captured on video a bear walking through our woods last Wednesday at 8:30 p.m. [nice photo-MH]
Rosemarie Koester, Providence Rd. November 8, coyote howling in back yard. November 14, a bear came and took the finch feeder. November 17, dead opossum on Depot Street. Two deer running through woods in back yard this morning. November 14, saw my first junco just now. Late this year. Happy to see him. At the feeder that has a new type of seed, one pair cardinals, six blue jays, goldfinch, house finch, purple finch, several juncos, white-throated sparrows just arrived, a Carolina wren, chickadees, titmice, sparrows, downy and red-bellied woodpeckers. Two red-tailed hawks seen over Tadmuck Rd. Thirteen turkeys came two days in a row, chipmunks, six gray squirrels.
Doug Pederson, Woodland Drive. November 8, first snow, first junco, first white-throated sparrow. Cooper’s hawk in tree near front door.
John Piekos, Dunstable Rd. November 9, bobcat close up caught on trail cam. [nice, very close photo-MH]
Elana Schreiber, Fletcher Rd. November 14. Saw a beautiful animal that I thought was a coyote. It was grays and browns and about 55 pounds, and very furry. His tail was bushy. He came through the yard fast, so no photo.
Marian Harman is a member of the Westford Conservation Trust, a non-profit conservation organization. Our purpose is the protection of Westford’s trails and open spaces. The Trust welcomes new members and volunteers. Visit our website at westfordconservationtrust.org, or check us out on Facebook.