R-squared in summary(lm...)

What is the difference between the two R-squareds returned for a linear
regression by summary(lm...)?  When might one report multiple vs. adjusted
R-squared?
Thank you,
Ben Osborne

Botany Department
University of Vermont
109 Carrigan Drive
Burlington, VT 05405

benjamin.osborne at uvm.edu
phone: 802-656-0297
fax: 802-656-0440