(Skeletonleaf Burr Ragweed or Skeletonleaf Bursage)
Skeletonleaf Bursage grows
along roadsides and on sandy sites on the plains. The plant has deeply dissected
leaves, giving it a "skeleton" appearance. Male flowers hang in umbels
from the top portion of the stem. Female flower heads are spiny burr-like structures
in the leaf axils with two carpels. The finely dissected leaves and spiny female
flowers help to separate A. tomentosa from other Ambrosia spp.
Ragweed pollen causes hay fever.
Compare to Ambrosia psilostachya,
which has less dissected leaves. Female
flowers of A. psilostachya lack spines.
Compare to Ambrosia trifida, which
is a taller plant with broader leaves. Female flowers of A. trifida lack
spines. A. trifida has a black rib on the involucre of the male flower