Flora of the Hawaiian Islands
Dicotyledon Literature for Cyanthillium cinereum
Robinson, 2007; Wagner et al., 1990, 1999; Lorence & Wagner, 2020.
   Asteraceae -- The Sunflower Family Bibliography
      Cyanthillium cinereum

Common name(s): ironweed, little ironweed
General Information
DistributionNative to tropical Asia, widely naturalized.In the Hawaiian Islands, naturalized on Ni`ihau, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Kaho`olawe, Hawai`i.

Annual herb, erect or decumbent, (5‒)15‒30(‒150) cm tall; stems finely striate, tomentulose with T-shaped hairs, sometimes glabrate with age.
Leaves scattered along the stem, petiolate; blade ovate, ovate-rhombic, or lanceolate, usually 2‒5 cm long, 1.5‒2.5 cm wide, adaxial surface pubescent with T-shaped hairs, abaxial surface pubescent and glandular punctate, margin remotely toothed; petiole ca. 1.5‒2.5 cm long.
Heads with 12‒16 florets; involucre campanulate, 4‒8 mm high; bracts imbricate in 3‒4 series, 3‒5.5 mm long, apex purplish; corollas lavender to purple, 2.5‒6 mm long; pappus whitish, inner bristles 3.5‒4 mm long, deciduous, outer bristles ca. 0.2 mm long, persistent.
Achenes rounded, nearly ribless, ca. 1.5 mm long.
David Lorence