1. Introduced Invasive Plants in California

2. Since the arrival of Europeans, approximately 1,000 plant species have been introduced in CA
140 species listed by the CA Exotic Pest Plant Council as “Plants of Greatest Ecological Concern”

3. How Invasive Plants Effect Native Biodiversity
Displace native species
Change the way a normal ecosystem operates
Can be hazardous to native fauna
Reduces biodiversity

4. European Beachgrass
captures sand, decreasing natural sand movement, and causing the dunes to increase in height
unsuitable as habitat for nesting snowy plovers
Displaces three particular species of plants including beach layia which is federally listed

5. Scotch broom
Interferes with the establishment of forests and invades natural areas.
Overruns pastures, utility corridors and roadsides increasing the maintenance costs of these operations.
Displaces the native plant species and the wildlife that depend on them.
Broom infested areas create a fire hazard.

6. Yellow starthistle Native to Eurasia
First found in Alameda county in 1869
Infests 42% of California
Lethal to horse if consumed
Decreases range forage quality
millions of dollars in losses probably occur from interference with livestock grazing
Depletes soil moisture

7. Tamarisk
Starting in the 1850s, several species of tamarisk were imported to the United States as ornamentals and for use in erosion control.
Starting in the 1850s, several species of tamarisk were imported to the United States as ornamentals and for use in erosion control
Aggressive invader of desert riparian habitats
Forms impenetrable thickets that suck up water leaving other plants, birds and fish high and dry (up to 300 gallons a day!)

8. Water hyacinth Escaped ornamental aquatic plant
Has invaded the Sacramento-San Juaquin Delta
Clogs boating waterways
competitively exclude native submersed and floating-leaved plants
Low oxygen conditions develop beneath water hyacinth mats

9. Arundo interferes with flood control crowds out native plants
chokes riversides and stream channels
interferes with flood control
crowds out native plants
It ignites easily and can create intense fires.
grows vertically without any horizontal branching and does not provide shading to the in-stream habitat, which can lead to increased water temperatures and reduced habitat quality for fish and other aquatic wildlife