(CNN) Congressional Cemetery is the final resting place of more than 68,000 so called 'permanent residents' with a distinguished list that includes J. Edgar Hoover - the former FBI director - and John Philip Sousa - the famed composer. But the caretakers here have a problem: invasive species that threaten this historic landmark.

So instead of using harmful herbicides, they came up with an inventive solution: goats.

On the menu for the grazers: poison ivy, poison oak, poison sumac, kudzu and English ivy.

"They're plants that are not native to Washington, DC." says Paul Williams, President of Historic Congressional Cemetery, "What happens is that goes up and it kills our trees. And then the trees fall onto the cemetery, damaging our headstones."

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