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Wilcox-Bushley Homestead
Boulder Lichens

Lichens General Information

 

Lichens are not a single entity but a community of organisms coexisting in the same body.  Members of this community vary but it usually consists of at least 4 major organisms: algae, fungi, bacteria and yeast.  Imagine 4 different kinds of animals living in the same home! Over 19,000 lichen species have been discovered (Lücking et al., 2017). Among the 19,000 species, the fungi, algae, yeast, or bacteria can be in various combinations which contributes to their amazing diversity. 

 

Lichens are unique in their capacity to tolerate extreme environmental conditions such as low temperatures, lack of water, and bright sunlight (Spribille et al. 2022). They can withstand conditions far more extreme than when either the fungal or algal partner exists on their own. Like a human community each partner contributes something that benefits the group.  In lichens, the algae produce sugars through photosynthesis that feeds the fungi, and the fungi produces a protective layer that prevents the algae from drying out and dying (Spribille et al.2022). Fungi also protect the lichen from herbivory, UV radiation, and the fungi obtain nitrogen that it gives to the algae promoting its growth (Spribille et al. 2022). Bacteria and yeast seem to help keep the lichen healthy by providing some nutrients, protecting against stress, and they decompose some of the older lichen body parts (Aschenbrenner et al. 2016).

 

Lichen growth forms

Field guides rely on the shape and physical features of the lichen body for identification.  The primary feature is the growth form.  All lichens begin with the germination of a single spore and grow outwards in a circular pattern. For lichens adhering to a rock or tree this will be the most common shape you see, but the circular body or thallus does not describe the growth form.  Growth form refers to how the lichen is attached to its substrate (rock, soil or tree) and whether the body of the lichen is two-dimensional (appearing flat) or three-dimensional (appearing bushy).

 

  1. Crustose lichens are lichens where the outside edge of the lichen cannot be lifted from the rock or tree.  To remove this lichen you would need to take a chip of the rock or tree bark.  In this growth form the fungal partner grows between the mineral grains of the rock or within the layers of bark.  These lichens look like paint that was splashed onto the rock surface or tree bark.

  2. Foliose lichens are lichens have an outer edge that you can lift and peer underneath.  The color and texture of the underside are important features used in identification. Undersides can be white, tan, or black.  Texture can range from smooth to hairy with some having vein-like structures.

  3. Fruticose lichens are three-dimensional lichens. They have upright reproductive structures that vary in shape and color and are sometimes bright red.

 

Here are photos and line drawings of the three major lichen growth forms.

​Image source https://ohioplants.org/lichenbiology/

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On the large glacial boulder in front of the QR post there are numerous crustose and foliose lichens.  Use the magnifying lens on your iphone or phone camera to help you find and see the following 4 species.  Do not touch or remove a portion of the lichen.  Simply use your eyes to make observations.

 

Crustose lichen -looks like a splash of paint

  1. Brown Cobblestone.  Look for this lichen on the side of the boulder facing either the field adjacent to the woods or the WB house.  This lichen looks like a fist-sized brown patch of paint and has a surface that is broken into small tile-like squares.

  2. Sunken Disk. This lichen is gray with warty patches on its surface. Little brown sunken disks can be found on its surface, hence its name.

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Brown Cobblestone

Sunken Disk

Foliose Lichens – have an outer edge that can be lifted from the rock or bark.

 

  1. Rock Greenshield. This light green lichen can be found near on the side of the boulder facing the road near its base. Its upper surface is smooth and shiny, with wrinkles.

  2. Peppered Rock Shield. Closer to the top of the boulder you can find this lichen best by looking for a narrow lobed pale green lichen with small brown circular structures on its upper surface. These structures are the reproductive organs of the fungi which forms the main body of lichens.  Fungal spores are released from these structures. 

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Rock Green Shield

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Peppered Rock Shield

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Phone: (860) 674-8545
Mail: P.O. Box 1, Farmington, CT 06034
Location: 119 Coppermine Road, Unionville, CT 06085

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