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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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Puncturevine
(goathead,
Mexican sandbur, Texas sandbur, ground bur-nut, land caltrop)
Zygophyllaceae, the caltrop family
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Background
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 Puncturevine is a naturalized invader from Europe. It
spreads by seed
and is most often found on sandy, dry, or gravelly sites. Puncturevine
produces sharply pointed burs that stick painfully in bare feet and cause
bicycle flats, reducing the recreational use of many areas. Seeds may
puncture even light truck tires.
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Description
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Puncturevine is a prostrate
annual that forms dense mats
up to 4 feet across. Leaves are opposite and
pinnately compound with 4 to 8
pairs of oval, hairy, 1/2-inch long
leaflets. Stems branch from the base and
from leaf axils and are slender and hairy. Flowers are 5 petalled, yellow,
1/2 inch wide, and borne singly in leaf axils from midsummer until frost.
Fruits are roughly circular, splitting into 5 sections, each with 2 large,
divergent spines. These tack-like burs contain up to 4 seeds.
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Distribution
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 Puncturevine
is throughout the U.S., except for the northern tier states from Montana to
Maine |
Control
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Biological control agents (seed and stem boring weevils)
provide fair to good control in Oregon, but control levels are uncertain in
Idaho. 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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