Among well over a million botanical specimens preserved at the Academy of Natural Sciences of Drexel University – a collection which volunteers since 2016 have been transcribing online for the Mid-Atlantic Megalopolis (MAM) Project – is a sprig of Xanthorhiza apiifolia, or yellowroot.  Picked in Philadelphia around 1815 but only mounted in 1857, this specimen bears a label that speaks to the history of botany in the United States and the wider world.  The brief cursive caption indicates that the sample came from the eminent American botanist, Charles Wilkins Short (1794-1863), and that it launched his collection de novo.  It reveals, further, that Short collected the sample with three companions, two of whom were significant naturalists of the age: namely, William Bartram (1739-1823) and the Portuguese priest and polymath José Francisco Correia da Serra (1750-1823), known to his American friends as “the Abbé Correia.”   This paper treats Short’s yellowroot specimen as a point of departure for studying the life and career of José Correia relative to the trans-Atlantic scientific and political world of the late eighteenth and early nineteenth centuries.  It approaches this subject through microhistory, a way of studying the past that examines little things and ostensibly minor occurrences to grasp larger events and social phenomena.  Here, microhistory can help us to see how a shared love of botanical (as well as zoological and geological) research drew Correia into a scholarly network that included not only Pennsylvanians like Bartram and Henry Muhlenberg (1753-1815), but also an international set of Enlightenment thinkers ranging from Carl Linnaeus (1707-1778) and Joseph Banks (1743-1820) to Thomas Jefferson (1743-1826) and Antoine Laurent de Jussieu (1748-1836).  Just as powerfully, the experiences of Correia show how scientific research in this period could become entangled in political upheavals and subject to political pressures.  In Correia’s case, the Portuguese Inquisition and the French Revolution disrupted his life and propelled migrations that led him to Philadelphia, where for a few years he found refuge and intellectual companionship.  The label on Short’s yellowroot specimen obviously remains silent on these larger issues.  It nevertheless offers clues for investigation while suggesting the potential value of herbaria for historical research in and beyond the field of botany itself.