Carduus pycnocephalus “Italian thistle” is a European annual weed of disturbed sites. While most thistles have inforescence heads borne singly, in this species several are clustered at the stem tip. Although present for many decades in Northern Cailfornia, it is a recent invader into the watershed, first reported in 1967.
Common name: Italian thistle
Scientific Name: Carduus pycnocephalus
Time of Observation: 7:46:27
Weather: Sunny, no wind
Temperature: 18 C
Location: Eaton Canyon Park, Pasadena, CA, US
Habitat: Alluvial savannah
Slope: flat terrain/depression surrounded by slight slope
Sun: complete exposure to sunlight
Water: no surrounding water seen
Soil: alluvial- sandy, gravelly soils
The Italian thistle was found off the main walking trail in a dry, desert-like, and alluvial area filled with stones. The invasive species often found in disturbed areas in soils with relatively high pH is spiny towards the tips. No flowers were seen on the plant during this summer season.
confer-harwood forest, forest edge
Northwest facing slope
Flowering, purple flowers, clustered heads
Carduus pycnocephalus, with common names including Italian thistle, Italian plumeless thistle, and Plymouth thistle, is a species of thistle. It is native to: the Mediterranean region in southern Europe, North Africa, and Western Asia; East Europe and the Caucasus; and the Indian Subcontinent.