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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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Yellow Toadflax
(butter-and-eggs) Scrophulariaceae,
the figwort family
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Background
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 Yellow
toadflax is likely an escaped ornamental brought to this country from
Europe. It spreads both by seed and roots. This weed contains a poisonous glucoside that may be harmful to livestock. Yellow
toadflax grows under a wide range of environmental conditions.
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Description
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Yellow toadflax is a perennial with narrow, nearly
opposite, 2-inch long leaves. Stems are smooth, generally unbranched, and up
to 3 feet tall. T he showy snapdragon-like flowers are about 1 inch long
(excluding the 1/2-inch spur), yellow with an orange throat and bloom from
summer to fall. Seed is produced in brown, globe-shaped capsules. Seeds are
round, dark colored with notched, papery collars that act as wings in
spreading the seed.
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Distribution
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Yellow toadflax is found throughout the U.S. and in nearly all areas except
western and south-central Idaho counties.
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Control
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Biological control agents (a defoliating moth, a seed head weevil, and a
flower beetle) provide fair control of yellow toadflax. 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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