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Poison Hemlock
Apiaceae (=
Umbelliferae), the parsnip family
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Background
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 Poison
hemlock is native to Europe. It contains highly poisonous alkaloids toxic to
all classes of livestock and humans. It has poisoned many who have mistaken
it for parsley. Poison hemlock is often found on poorly drained soils,
particularly near streams, ditches, and surface water.
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Description
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 Poison
hemlock is a biennial that grows up to 10 feet
tall. Stems are stout, hollow, ridged, and mottled with purple spots. Leaves
are shiny green, 3 to 4 times pinnately compound, and
clasp the stem at the
obvious nodes. Crushed foliage has a disagreeable, mousey odor. Flowers are
small, white, and borne in umbrella-shaped clusters about 3 inches across
in early summer. Seeds are ridged and flattened, with 2 seeds borne
together. The plant has a thick, white
taproot.
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Distribution
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 It
grows throughout the U.S. except from eastern Montana to northeastern
Minnesota and south to Nebraska. It has an extensive presence in Idaho. |
Control
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A biological control agent (a
defoliating moth) provides good to excellent but inconsistent control.
Herbicides are also available.
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© 1999 University of Idaho:
Text and photographs for these pages from Idaho's Noxious Weeds, by
Robert H. Callihan and Timothy W. Miller (revised by Don W. Morishita
and Larry W. Lass).
Please contact: Ag Publishing, University of Idaho, Moscow,
Idaho 83844-2240; 208 882-7982 visit the Resources for Idaho website at
http://info.ag.uidaho.edu, for more information about this or other
publications.
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Skeletonleaf Bursage (bur
ragweed, silverleaf, povertyweed)
Asteraceae (= Compositae), the aster
family
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Background
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 Skeletonleaf bursage is native to the Great Plains
region. It spreads both by seed and creeping roots, keeping primarily on,
but not limited to, dry or poorly drained sites.
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Description
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Skeletonleaf bursage is a
perennial up to 3 feet tall.
Leaves are alternate, up to 5 inches long, and very deeply
lobed with
coarsely toothed margins. The lobes are reduced in size from leaf base to
tip. The upper leaf surface is
 greenish gray and may have rough hairs; the
lower surface is white with short, dense hairs.
Flower heads are 1/4 inch wide and are produced from June through August.
Each head contains inconspicuous yellow flowers that are either male or female (not
both). Fruits are 2-seeded, light brown burs with up to 10 short spines. The
plant has extensive horizontal roots.
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Distribution
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 Skeletonleaf bursage occurs from the desert Southwest
to Wisconsin and Illinois and in these indicated Idaho counties.
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Control
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No biological control agents are available for skeletonleaf
bursage, but herbicides are available for control of this weed.
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© 1999 University of Idaho:
Text and photographs for these pages from Idaho's Noxious Weeds, by
Robert H. Callihan and Timothy W. Miller (revised by Don W. Morishita
and Larry W. Lass).
Please contact: Ag Publishing, University of Idaho, Moscow,
Idaho 83844-2240; 208 882-7982 visit the Resources for Idaho website at
http://info.ag.uidaho.edu, for more information about this or other
publications.
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