Panorama of the San Marcos Foothills Preserve
Plants of the San Marcos Foothills Preserve

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Carduus pycnocepnalus (Italian Thistle)

Fairly common, non-native annual found in scattered locations throughout the Preserve. Flowers are rose-purple. Booms in Spring.

Carduus pycnocephalus (Italian thistle) seedling (right) compared to Silybum marianum (milk thistle) seedling (left). Note that milk thistle has white ("milky") veins. True leaves on Italian thistle seedlings tend to developed asymmetrically (i.e. one leaf larger than the other).


Carduus pycnocephalus (Italian thistle). NON-NATIVE. Pictured in winter. Note developing seedling.


Carduus pycnocephalus (Italian thistle). NON-NATIVE. Flower head pictured in late winter.


Carduus pycnocephalus (Italian thistle). NON-NATIVE. Leaf pictured in late winter.


Carduus pycnocephalus (Italian thistle). NON-NATIVE. Stem pictured in late winter.


Carduus pycnocephalus (Italian thistle). NON-NATIVE. Pictured in Summer.


Carduus pycnocephalus (Italian thistle). NON-NATIVE Pictured in summer.