The Historical Phytogeography of Cirsium arvense, An Invasive Species in Pennsylvania

According to the Department of Conservation and Natural Resources, Cirsium arvense (Asteraceae family) is currently an invasive plant in the state of Pennsylvania. Invasive species pose a problem as they are detrimental to natural ecosystems and very costly to manage and eradicate. In this study, distribution of C. arvense in Pennsylvania was reconstructed using only herbarium records. Through detailed methodology, it was determined that there were no shifts in habit preference over time. With the data being specific to Pennsylvania, the objective was to determine if the distribution and habitat preference would align with the current literature on what is known about C. arvense. The data seemed to support the current literature in that C. arvense appeared to be widespread and prefers dry, disturbed areas like roadsides. However, with further analysis, the data was found to reflect trends in field collecting as opposed to the distribution of the species. One of the limitations of the study was collector bias in addition to procedural obstacles. From this study, valuable insight was gained about the future of botanical collecting techniques and the importance of phytogeographical studies.