I reported this cottonwood in the Charles River floodplain in West
Roxbury, Massachusetts a year or so ago. I was never happy with the
height measurement so I went back and tried to nail it down. The
highest twigs are very difficult to isolate (aren't they all?) with a
decent view of the trunk through surrounding red maples and thicket.
 From two different vantage points I was able to come up with
consistent enough results, 110.34' and 110.45', naturally I'll take
the high measurement. I had a third measurement that promised to be
in the 112' + range but I couldn't get a clear shot to the base of
the trunk to finish the bottom sine figure.

Eastern Cottonwood
CBH 13' 6"
Height 110.45

Photos of the tree here:
http://www.flickr.com/photos/naturejournal/sets/72157615035370313/

Andrew Joslin
Jamaica Plain, MA