The introduced and invasive flora of Bermuda

Abstract Screening incoming plants for potentially invasive species is key to preventing new invasions on islands. Doing this effectively requires knowledge of plants already present and invasive in the country, and which pathways, donor regions and plant families have previously contributed the most invasives. As Bermuda previously lacked such a dataset, we compiled a comprehensive inventory of the native, introduced, casual, naturalized and invasive plants from historic and modern literature, herbarium records and garden centre visits. The inventory contains updated taxonomy, pathways and dates of introduction, native geographic range, life form, and naturalization status for 1587 vascular plants from 162 families. Of these, 1424 species (89.8%) are introduced to Bermuda, while 151 (9.5%) are native. Classifying stage of invasion shows 321 species (22.5% of the introduced flora) have escaped cultivation to form casual, naturalized or invasive populations. Bermuda currently has 217 naturalized plants of which 52 are considered invasive. We define invasive species as non-native to Bermuda, reproducing in the wild and recruiting offspring at multiple sites, dispersed over long distances or large areas, or excluding other plants from habitats (Methods S1). We did not directly consider impacts in our definition of invasive species. Among the invasives 25 species (48%) are trees and shrubs, mostly of Asian origin. Ornamental horticulture was the introduction pathway for 75% of invasive plants, emphasizing the need for further collaboration with the commercial horticulture sector and private gardeners to reduce invasion risk from ornamental plants.