Poppies

The Amazing and Complex Lichen Community

Tuesday, Nov 1, 2022

The ecological definition of community is “an association of organisms in an area which are interdependent on each other.” We find examples of community throughout nature, from songbirds that forage together for protection to the dusky-footed woodrat whose home is shared with salamanders 
and mice.

Adorning almost every tree at Tilden Nature Area is a unique organism called lichen. Lichens are composite organisms containing a photosynthetic symbiont - algae or cyanobacteria - living on the filaments of multiple species of fungi. The fungal partners provide the structure for the photosynthetic partners, who in turn provide a food source.

One of the heartiest living things known, lichens are the first to populate bare rock exposed from landslides, thrive in the freezing arctic tundra, and grow in the world’s hottest and driest deserts. They have also been demonstrated to survive in the irradiated vacuum of space and, more recently, in a simulation of the surface of Mars.

Lichens are survivors because each member of their community provides for the other and fills a necessary role. Without the photosynthetic partner, the fungal partners, or the many other microorganisms that interact with them, lichens cannot exist. These community members need each other to survive and are stronger together.

Sunburst Lichen Hike

Interested in unique flora and fauna? Take an easy self-guided hike and discover why so many like the lichen! In the Tilden Nature Area there are several species of lichen, including the common sunburst, Xanthoria parietina. Ranging in colors of green to orangish red, sunburst lichen commonly grows on wood and bark, and you’ll often find it on our oak trees.

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Tilden Nature Area lichen hike
Sunburst Lichen Hike at Tilden Nature Area
  • Start at the traffic circle of Tilden Nature Area and continue along Wildcat Creek trail.
  • At Jewel Lake, make a left to cross the bridge and continue along the path around Jewel Lake.
  • Make a right at the Y to take Upper Pack Rat trail.
  • At the next Y, make a left to continue down Pack Rat trail and end back at the traffic circle.