- Author: Dr. Paul Pratt
- Editor: Guy B Kyser
It may be widely understood that most aquatic and wetland weeds are spread by water currents, but the patchwork of colonizing exotic plants can be puzzling. Why do weeds establish in some places but not others? Generally, the number of propagules (seeds or plant fragments) moving in a watershed is assumed to increase downstream. This assumption influences management decisions, such as prioritizing management efforts between upstream and downstream areas of a river to reduce reinvasion.
Uruguay waterprimrose (Ludwigia hexapetala) is an emergent aquatic weed from South America which has invaded many riverine wetland ecosystems in the western US and Europe. This is a clonal plant which can reproduce asexually via shoot...