Flora of the Hawaiian Islands
Dicotyledon Literature for Centaurea melitensis
Wagner et al., 1990, 1999.
   Asteraceae -- The Sunflower Family Bibliography
      Centaurea melitensis

Common name(s): knapweed, star thistle, Napa thistle, yellow star thistle
General Information
DistributionNative to Europe.In the Hawaiian Islands, naturalized on Ni`ihau, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Kaho`olawe, Hawai`i.

Annual or biennial herbs; stems several from the base, 1-5(-8) dm long, branched in upper part.
Leaves oblanceolate in outline, 5-10 cm long, pinnately lobed, upper leaves nearly linear, 1-3 cm long, base decurrent, forming narrow wings on the stem.
Heads in the upper leaf axils; involucre nearly globose, the bracts very firm, often arachnoid pubescent near the tip when young, abruptly constricted at apex to a sharp spreading tip 3-9 mm long, each margin with several very short spines near base of tip; corollas yellow, 8-10 mm long; pappus of bristles in several series, 3-4 mm long.
Achenes attached at a lateral notch slightly above the base.
2n = 22, 24, 36