PLUMELESS THISTLE, Carduus
acanthoides L. 1, upper portion of plant showing stem, leaves,
and flower head; 2, seed. Biennial as a rule, but sometimes
winter annual or annual. Stem erect, with spiny wings, 3 to 6 feet
(0.9 to 1.8 m) tall, branched. Leaves deeply divided with alternate
lobes. Rosette and lower stem leaves large, decreasing in size up the stem;
hairs scattered on upper leaf surface, denser on lower surface, especially
along midrib. Lobes on leaves and stem ending with white to yellowish spine.
Flower heads globe-shaped, erect, single or loosely clustered, with
spiny wings to base. Blooms reddish-purple, 1/2 to 1 inch (1.3 to 2.5 cm)
in diameter, occurring from late May through early July. Seed maturing
5 to 12 days after full bloom; oblong; usually straight but sometimes slightly
curved; straw-colored with brown striations to collar where pappus is attached.
Pappus light-colored, not plumed. Found in pastures, meadows, and