Findings of the Second Edition of the Urbanizing Flora of Portland, Oregon

The first edition of the Urbanizing Flora of Portland, Oregon 1806-2008 (Christy et al. 2009) catalogued and reviewed herbarium specimens and botanical publications dating back to 1806 to analyze the impacts of urbanization on the regional flora over this period. Building upon this work, an effort was undertaken in 2019 to update continuing changes to the regional flora, including newly introduced and/or discovered vascular plants through 2024 using herbarium specimens, observations, online databases, and local botanists’ expertise. This effort resulted in the publication of a second edition in 2024 (Kimpo et al.) where 1,942 vascular plant taxa from 139 plant families are described, with historical (pre-1980) and recent (1980 through 2024) notes on their origin, distribution, and habitats. The updated list of vascular plant taxa represents about a 25% increase compared to the 1,553 taxa from 126 plant families presented in the 2009 publication; however, the 2024 publication also represents about a 56% increase in geographic area reflecting an expanding urban footprint while condensing some subspecies and varieties under a single species. Of the 1,942 taxa listed, about 50% are considered native and the other 50% are either considered fully exotic (49%) or a mix of exotic and native or unknown (1%). Additionally for the second edition, previous data were questioned (and corrected when necessary), specimens re-visited and georeferenced, and a discussion of the utility and shortcomings of both traditional and modern sources of botanical information was provided.