Land Plants - invasive

Milk Thistle (Silybum marianum) on Jun 24, 2019

Submitter does not have a specimen
EDRR Status: Local expert notified

Description of specimen

Carduus nutans is as close as I can come in Weeds of the West, but it has some kind of variegated leaves, i.e.white lines between major veins. Head looks right. (The head looks MEAN! and the leaves not much more friendly.)

Approx. 4 ft. tall. Purple flowers. Involucre very spiny; bracts with spines approx. 2 cm; Approx 7 cm from bract spine tip across inflorescence.
Leaves mostly > 15 cm.; deeply dissected with spines at tip of each lobe. Lvs clasping stem. I didn't look closely, but from 1-2 ft away plant looks hairless.

I can't tell for sure, but it seems biennial. It may have been there last year; it is probably a < 3 yr old patch.

Plant in flower, fruit, and past fruit. (Probably too late for 2019 control.)

1. Patches near Start Mooring are about 30 ' x 30 '; thick and in dense poison oak. Adjacent to hazelnut orchard and young vineyard. :(
2. A few individuals on roadside near 31100 NE Wilsonville Rd.
musk(?) thistle at Star Mooring; whole plant  All photos June 24, 2019 near Star Mooring Farm, Wilsonville Rd, Newberg thistle stand= white tops on left and right N side Wilsonville Rd near Star Mooring (dark green is poison oak) Lower leaves of thistle showing white lines cauline leaf length~ 15 cm width across involucre ~ 7cm

Commentary

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