The impact of exotic weed competition on a rare New Zealand outcrop herb, Pachycladon cheesemanii (Brassicaceae)
Nearly one quarter of New Zealands unique vascular plant flora is threatened, and weed invasion is implicated in the decline of more than half of these threatened species. However, there is little experimental evidence showing that invasive weeds have a direct impact on threatened native plants. This study experimentally tested the hypothesis that competition with invasive weeds threatens the rare outcrop plant Pachycladon cheesemanii (Brassicaceae).