During digitization of several hundred thousand plant specimens from the Northeastern United States held in the Academy of Natural Sciences herbarium (PH), a specimen of green comet milkweed, Asclepias viridiflora, was found that had been collected from the Gettysburg Battlefield within months of the momentous battle in July 1863. The specimen was collected by Academy botanist and horticulturist Thomas Meehan, whose brother Joseph Meehan had served in the Union Army and was present at the battle of Gettysburg. This paper explores the connections of the Meehan brothers to Gettysburg, the condition of the battlefield just after the battle and some 40 years later, and the possible reasons for the collection of this historical specimen.