Invasive Plant Species
Invasive plants are one of the greatest threats to croplands, rangelands, aquatic areas, and wildlands in the United States; they degrade the productivity and biological diversity of all ecosystems. The problem increases each year as new species are introduced and established.
The sixteen most harmful weeds in Humboldt County include: Scotch broom (Cytisus scoparius), Pampas grass (Cortaderia jubata), gorse (Ulex Europaea), Himalaya berry (Rubus discolor), English ivy (Hedera helix), Cape ivy (Delairia odorata), European beachgrass (Ammophila arenaria), Ice plant (Carpobrotus edulis), yellow bush lupine (Lupinus arboreus), yellow star thistle (Centaurea solstitialis), spotted & diffuse knapweed (Centaurea maculosa & Centaurea diffusa), bull & Canada thistle (Cirsium Vulgare & Cirsium arvense), common reed (Phragmites australis), Spanish heath (Erica lusitanica), and Chilean cordgrass (Spartina densiflora).
There is more information about weeds from the University of California at Davis http://wric.ucdavis.edu/