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

Common name(s): ragweed, common ragweed
General Information
DistributionNative to the United States and southern Canada.In the Hawaiian Islands, naturalized on O`ahu, Moloka`i, Maui, Hawai`i.

Erect, taprooted annual herbs; stems 3-10 dm long, branched at least above, ± hirsute.
Leaves pinnatifid or bipinnatifid, the lobes lanceolate, blades narrowly to broadly ovate or elliptic, 4-10(-30) cm long, 4-7(-15) cm wide, upper surface hirsutulous, lower surface strigose and often hirsute on the veins.
Male involucre 1.5-2 mm high; female involucre 3-5 mm high in fruit with a single series of short, sharp, erect spines near or above the middle.
2n = 34, 36