Submitted to: Michigan Botanist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2000
Publication Date: N/A
Interpretive Summary: There is growing awareness that non-native plants can become invasive, displacing native plants and disrupting natural ecosystems. Thus it becomes increasingly important that we document situations where we discover new, non-native plants growing in natural settings without cultivation. It is also important to describe these plants accurately and to alert field botanists and naturalists of their occurrence, so that these plants can be monitored for any signs of invasiveness before they can cause serious ecological damage. This paper is the first documented report of an Old World bramble, the European dewberry (Rubus caesius), found away from cultivation in the north central United States, more specifically, in Iowa and Michigan. The authors give a brief history of the introduction of this species into the US, a description of sites where the plant has been recently located, and straightforward ways that field workers can distinguish this species from other, native dewberries. This report should be valuable in alerting field workers to this little-remarked alien dewberry and giving them the tools needed to identify it.
Technical Abstract: Rubus caesius, the European dewberry, has recently been discovered on uncultivated sites in Iowa and Michigan. It has been noted as a rare escape from cultivation in the eastern United States, but had not previously been collected in the north central states. This report presents a historical account of the introduction of this species into the United States, speculation regarding its introduction to Iowa, a description of recent collection sites in Iowa and Michigan, and a listing of diagnostic features that can be used to distinguish R. caesius from other, native dewberries. These features include first-year canes that are glaucous and tinged red where exposed to sunlight, ovate-lanceolate stipules, complex, corymbose inflorescences, and fruits consisting of few, relatively large drupelets that are black and glaucous. It is hoped that this report will alert field botanists and naturalists to this alien addition to our local flora.