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Diminutive Decorators
by Mary Jasch
Got lichens? You're breathing clean air!
Aside from being Nature's subtle pollution sensors and mini-decoration on rock, tree, and soil, with harm to none, lichens are mysterious pioneer species.
They eat rocks, make soil, produce brilliant purple dyes, and are used as shingles on bird nests. People use them in floral arrangements, antibiotics, litmus paper, and perfumes. Some are 4,500 years old.
On a recent crisp January day, Dorothy Smullen, ex-high school science teacher, Marian Glenn, biology professor at Seton Hall University -- both lichen aficionados --and this writer took to the woods at High Point State Park in northwestern New Jersey on a hunt for the little lovelies.
Just inside the gate we pull off road and look at tree trunks covered in lichens of different shapes, colors, sizes, and designs. The hunters take out hand lenses and glue themselves to oaks and ash. We hardly move.
The obvious lichens on bark are foliose (leaf-like with an upper and lower cortex). The other two forms are crustose (you have to scrape it off the substrate and need a compound microscope to identify it), and fruiticose (an upright form).
Lichens are the neglected part of the fungi kingdom and are more studied by botanists, Glenn says. A foliose lichen has a layer of green-celled algae sandwiched between two outer layers of fungus. The algae and fungus are mutually symbiotic, but “All these things are a question of perspective," Glenn says. “The fungus provides habitat for algae, so the algae couldn't live without the fungus. The fungus gets the benefit from the algae, which provides all of the nutrition by performing photosynthesis."
Cyanobacteria, which also fixes nitrogen, sometimes inhabits the lichen. Chemicals in the fungus absorb ultra-violet light and are sunscreens that protect the algae. Some scientists believe the relationship is a controlled parasitism in which the fungus devours the algae.
“You usually see lichens more heavily on the north side of a tree," says Glenn, a member of Bryological and Lichenological Society. “Red oak is a good tree for lichens." "On an ash tree growing in the city you wouldn't have any of this. When you come here, the trees have a completely different energy."
- Glenn
We head for the Cedar Swamp Trail and spy a boulder with two kinds of rock tripe - brown rubbery smooth rock tripe and bumpy toadskin.
Along the gravel road to the swamp, the hunters brake for a patch of mixed Cladonia species -- spiky little urchins with brown or red caps, some forked, some with powder horns strutting above their squamosa -- all worth crawling on your knees for. Soon, a pink lichen in the mold group! Tiny treasures! On a nearby tree, bright yellow crustose next to a silvery species laden with apothecia - tiny tart-like fertile structures that release fungal spores. Lichens on the roadway, lichens on soil that prevent wind erosion, on trees, rocks...everywhere.
When lichens are in an environment where they grow vigorously, they'll grow on almost anything. They want moisture and bright light, and have preferences for substrate, such as pH, nutrient quality, and the nitrogen-rich bark of ash, walnut, apple. Some prefer conifer bark for its lower pH. One species grows on rocks underwater in fast-flowing, clear, streams at high elevations.
The blue-grey color on Atlantic white cedar, Smullen says, is a Lapraria species consisting of powdery granules. Lichenologists debate whether Lapraria is only a juvenile stage that dies. But if so, how does it reproduce? And I thought it was just the color of cedar. A turkey-like peppered rock shield lichen covers a rock with moss. The sensitive-to-sulfur-dioxide hooded tube lichen hangs from Mountain Laurel. When it reproduces, its inflated lobes burst open like trumpet lips covered with powdered sugar. Tarts on a dying red maple wait to erupt.
“As a tree dies it releases nutrients, so lichens grow vigorously on branches that are dieing," Glenn says. “They need light, so branches with no leaves or needles support more lichens. They grow with only the water of the dew. The algae becomes hydrated and photosynthesizes for two hours before the dew evaporates."
On trees, lichens are epiphytes or they grow on each other.
On rock, they dissolve minerals and create soil. They provide a nice base so that if a moss spore or seed falls on a lichen rather than bare rock, it's more likely to germinate and grow. “A lichen may end up dying as a result of a spore germinating and covering it up. On that micro scale, we can understand how succession takes place," says Glenn.
Lichens aggregate soil particles. The hyphae penetrate soil, providing a netting that helps prevent erosion. They do this on a finer scale than plants do. Some lichens have root-like rhizines. Others are “soil crusts," forming a hyphael network on the soil surface.
The relation of lichens to air quality is its most determining survival factor. They grow in high nitrogen areas including trees in horse pastures where they pick up volatile ammonia, under bird perches and around feeders.
“Lichens are just out there," Glenn explains. “If you imagine trying to display sensors over an area the lichens are out there as air quality sensors. They are useful indicators of pollution. If the air is clean, as pollution develops, they drop out of less favorable habitats."
“The ruby-throated hummingbird makes its nest of cinnamon fern hairs, spider webs, then the female picks off the lobes of Punctelia and Flavoparmelia and camouflages the nest. The lichens also repels water," says Smullen, New Jersey Mycological Association member.
Lichens on boulders placed in the landscape are short-lived or grow very slowly, up to 1 millimeter a year. They grow best under a forest canopy. Plants, whether they're trees or grass, increase the moisture level through transpiration, as opposed to paved surfaces.
But for those who insist on having moss and lichen-encrusted boulders in their gardens, Glenn gives this advice:
1. try to reproduce the original micro-climate or those lichens will not last long
2. re-orient the boulder the way it was in the wild. If the lichens were facing north, face them north in your yard. Was the boulder in the open or under trees?
If you want lichens in your garden, place a rock where you can feed the birds who, in turn, will give it a little fertilizer. But if you want to see some real beauties, take a walk on a wooded trail, a little off the beaten path. Bring a hand lens and prepare to spend some time peeking at a colorful world in miniature.
LICHENS OBSERVED ALONG THE KUSER NATURAL AREA
and CEDAR SWAMP TRAIL, High Point State Park, 1/2/07 compiled by Dorothy Smullen
Foliose on bark
Flavoparmelia caperata common greenshield lichen
Punctelia rudecta rough speckled shield lichen
Punctelia subrudecta powdered speckled shield lichen
Parmelia sulcata hammered shield lichen
Pseudevernia consocians antler lichen
Hypogymnia physodes hooded tube lichen (sensitive to S02 pollution)
Physcia milligrana mealy rosette lichen
Phaeophyscia sp. (white medulla)
Parmeliopsis subambigua (collected as unknown - best id- pale underneath with brown short rhizines, pustular soredia clusters all over lobes)
Foliose on rock
Flavoparmelia baltimorensis rock greenshield lichen
Xanthoparmelia conspersa peppered rock shield
Umbilicaria mammulata smooth rock tripe
Lasallia papulosa toadskin lichen (pustules on surface)
Fruticose on soil
Cladonia rei wand lichen (brown apothecia)
Cladonia coniocraea powderhorn lichen
Cladonia chlorophaea mealy pixie-cup
Cladonia cristatella British soldiers
Dibaeis baeomyces Pink earth lichen or pink mushroom lichen
Crustose thallus and fruticose apothecial stalks
Cladonia ciliata?
Crustose on bark or rock
Candelariella sp. ?
Bacidia sp. ?
Ochrolechia sp. ?
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published January 30, 2007
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