These bald cypress trees (Taxodium distichum) have been planted along a pond in Lake Sullivan Park in Indianapolis. This is at the edge of the parking lot for the velodrome. Bald cypress trees lose their leaves in the fall, don't cut them down in the winter thinking they are dead pine trees. They are coniferous like pine and spruce but they are also deciduous like maple trees.
Bald cypress trees will grow these knees when they are in soil that has a consistently high water table like at the edge of this pond. Bald cypress will also grow quite well in dry soil too but they won't show these knees in that case. You can also find bald cypress with knees like this planted along the Central Canal in downtown Indianapolis.
Bald cypress cones. The bald cypress is native to Indiana but doesn't naturally occur this far north. These pictures were taken November 14, 2009.
Link to Taxodium distichum:
Link to Lake Sullivan Park: