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Name: Austin
Status: other
Grade: other
Location: CA
Country: USA
Date: Fall 2010

Question:
Hi there, I have a question regarding lichen and mosses. I have heard that lichen persists over many years, and that the reason we do not see it during the drier months (summer) is that it browns and blends in with its substructure. Is this true? Does this hold true for moss as well? Or is it only ephemeral, appearing during the wet seasons, and then dying and disappearing--and so the moss that grows in the following year, possibly in the same place, is completely new moss that has germinated?



Replies:
Lichens can persist for many years. Lichens reproduce both by diaspores, and by vegetatively spreading -- there is even a science of lichenometry to estimate the age of exposed rock surfaces based on the spread of a particular lichen.

http://en.wikipedia.org/wiki/Lichen#Growth_and_longevity

There are different colors and growth forms of lichens:

http://www.ucmp.berkeley.edu/fungi/lichens/lichenmm.html

some more noticeable than others.

Mosses reproduce both by spores and vegetatively spreading.

http://bryophytes.science.oregonstate.edu/page3.htm

Mosses tend to "green up" after taking up water from rain, so they may be more noticeable then.

Anthony Brach
Missouri Botanical Garden
c/o Harvard University Herbaria



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