Invasive Species: Italian Thistle
Carduus pycnocephalus
Italian thistle originated in western and southern Europe as indicated by its name. It has since spread to temperate climates around the world. It was first reported in Oregon in 1929 in Lane County and in later decades found perfect habitat in Douglas County’s hillside pastures, covering tens of thousands of acres. It has been on the Yamhill County weed list since 1990 and we need your help to control it! It was first documented in 1959 in Multnomah County.
Why is it important to control?
As alluded to above, this thistle can take over fields, every year dropping more and more seed, until there is nothing but thistle. It degrades the economic value of pastures and croplands. It crowds out native annual grasses. It is quick to go to flower and go to seed so that those seeds can germinate before the dry times of summer arrive. The seeds blow on the winds onto neighboring properties.
How can you identify it?
| Habitat: | Pastures, cropland, meadow, roadsides |
| Life Cycle: | Annual or Biennial |
| Height: | Up to 6-8 feet (1.8-2.5 meters) |
| Leaf Description: | Deeply lobed with white spots; underside slightly wooly |
| Fruit & Flower Description: | Purple flowers; spines on flower bulb |
| Bloom Time: | May to June |
