A naturally occuring circle of
redwood trees
(Sequoia sempervirens).
The redwoods of California flower, and produce cones each year. The cones, between 2 and 3 cm long, contain the seeds of the next generation of redwoods-- or so you might think. Each mature redwood tree can produce as many as 250,000 seeds annually (each about the size of a tomato seed), but most redwood seeds do not sprout and grow into trees. A normal rate of germination rate may be anywhere from 0.23% to a mere 1.01%.
Instead, many redwood trees are
clones-- they sprouted from the base of a
mature tree, and are able to use the
nutrients and
roots from the original tree. When the mature tree dies, or is logged, what is left is a circle of younger trees,
colloquially known as a 'fairy ring.' Surprisingly, genetic analysis of these rings have found diverse
gene stocks in the rings: non-clones (
seedlings) "complete" the circle.
Sources:
Becking, Rudolf W. 1996. "Seed Germinative Capacity And Seedling Survival Of The Coast Redwood (Sequoia Sempervirens)" Conference on Coast Redwood Forest Ecology and Management . 18-20 June 1996, Humboldt State University, Arcata, California. <http://www.cnr.berkeley.edu/~jleblanc/WWW/Redwood/rdwd-Seed.html> (30 August 2004)
W. J. Libby, T. S. Anekonda, J E. Kuser. 1996. "The Genetic Architecture Of Coast Redwood." Conference on Coast Redwood Forest Ecology and Management . 18-20 June 1996, Humboldt State University, Arcata, California. <http://www.cnr.berkeley.edu/~jleblanc/WWW/Redwood/rdwd-The-7.html> (30 August 2004)
California Department of Parks and Recreation. "About Coast Redwoods." <http://www.parks.ca.gov/default.asp?page_id=22257> (30 August 2004)