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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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Field Bindweed
(Convolvulus arvensis)
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Background
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 Field bindweed is a Eurasian native that has thoroughly naturalized
itself in North America. It reproduces both from
seed and creeping roots and is found in extremely diverse environmental
conditions. Seeds can remain viable in soil for 50 or more years. Field
bindweed is agriculture's twelfth most serious weed species. |
Description
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 Field bindweed is a
perennial vine that dies back each
year. Leaves are alternate, up to 2
inches long, and arrowhead shaped. Twisted stems may be 6 feet long, forming
dense mats or climbing other vegetation. Flowers are borne in leaf
axils from June until September, are white
to pink, 1 inch wide, and funnel shaped. A pair of small
bracts is found ¼ to 1 inch below the
flower. Seeds are hard, triangular, and borne in groups of 4 in a capsule. |
Distribution
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 Field bindweed is found throughout the U. S. except for the extreme
Southeast, and southernmost Texas, Arizona, and New Mexico. |
Control
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Biological control agents are
unproven, but herbicides can control this weed. Tillage 2 weeks after the
plant emerges and continuing every 2 weeks during the growing season over a
period of 2 to 3 years will also kill the plant.
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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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