Italian thistle
Carduus pycnocephalus L.)

Weed ID Links   Photo's: Seedling/Young Plant    Seeds      Flower     Plant

Biological Control
Photo from: Yolo County Resource Conservation District,
Roots: The Italian thistle has long, thick taproots, it is occasionally branched, and it is capable of penetrating 40 cm or more deep into the soil.  (1)

Stems/Leaves: Its stems and leaves are quite prickly.  (1), (4), (5)

Flowers: It has deeply lobed disc flowers.  They are purple to pink and are rarely white.  The seed heads are spine tipped, and are overlapping in several rows.  The flowers are flat, and densely covered with cream colored bristles interspersed among the disk flowers.  Insects pollinate it more than any other pollinator.  (1, 3)

Fruits and Seeds: The seeds are curved and slightly compressed.  It is sometimes slightly 4 to 5 sided in cross section.  (3)

Method of Reproduction: When Flower buds seeds pop out and are taken by wind or are carried on animals until seed falls off.  (1)

Environments Favorable to Infestation: Warm with some moisture environments is best for this plant.  (1), (2)

Control Methods:
Non chemical: You are able to mow to help reduce this plant but it will not eliminate the plant.  The Italian thistle recovers quickly from the buds near the base.  After the initial flowering the best times to mow are 2 to 4 days.  Tillage is also a good way for control.  (1)

Background: This plant is native to the Mediterranean region of Southern Europe.  (1)

Distribution: It is distributed throughout the following areas: Southern North Coast Ranges of California, Sierra Nevada foothills, Central Coast, San Francisco Bay region, and also South Coast Ranges up to a height of 3300 ft.  (1)

Here are some other Links:

1) Steve, Schoenig, EncycloWeedia.  [online] available. 3/10/2004.

2) Carla Bossard, Richard Lichti, California Invasive Plant Council.  [online] available.  3/29/2004.

3) Dana, Coggon, Noxious Weed Control Board.  [online] available.  3/29/2004.

4) Athena Demetry, Sequoia and Kings Canyon National Parks.  [online] available.  4/5/2004.

5) Terry Cacek, National Park Service IPM.  [online] available.  4/7/2004.

By Jason Madsen   date: 4/8/2004. HOME     Back to New Weed Invaders