Urbanization has global impacts on ecosystems and transforms landscapes into man-made constructs. As urbanization continues to encroach on landscapes it is important to understand its effects on biodiversity and the long term health of our planet. In terms of species numbers, urban floras can actually be more diverse than their native surroundings and I am specifically interested in the species that have been introduced into these settings, their provenance, and the historical circumstances of how they were established. I collected plants in the alleys of Tempe, Arizona over a 5 month period to get a baseline understanding of the local diversity; then collected data from herbarium records using SEINet http://swbiodiversity.org/seinet/ to trace the origin of the introduced species and the first record of their appearance. I also used on-line information from the City of Tempe to investigate the relationship of land use change, development, and population growth to the introductions of some non-native plants. Finally, I used SIENet records to investigate the relationship of collection intensity throughout the decades to the introductions of some non-native plants. A total of 130 specimen were collected representing 83 different species from 32 different families. Most of the introduced species were from climates similar to Arizona. New occurrence records were spread out over the decades that Tempe has been around, and I was only able to weakly link them to the historical and collection intensity data. Knowing the biodiversity of an area can give clues into the ecosystem services that biodiversity provides, as well as management implications. Additionally, knowing the history of what is out there may give insights into what the biodiversity of the future may look like.