
Japanese honeysuckle (
Lonicera japonica) is an invasive plant that is common, especially in southern parts of Indiana. These fencerow trees are covered with
Japanese honeysuckle vines.
REVISION 1/17/2013: These vines are not Japanese honeysuckle, but rather they are wintercreeper vines (
Euonymus fortunei) which is another invasive vine that is a big problem in Indiana.
Both wintercreeper and Japanese honeysuckle vines keep their leaves throughout the Indiana winter, staying more or less green. These pictures were taken in Shelby County near Shelbyville, April 1, 2011.

A closer look at the wintercreeper vine seen in the previous picture.
Link to Euonymus fortunei: