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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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Silverleaf Nightshade (white
horsenettle, silverleaf nettle, bullnettle)
Solanaceae, the nightshade
family
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Background
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 Silverleaf Nightshade is native to the central U.S. The
plant spreads by seeds and rhizomes, and grows under a variety of
environmental conditions. Berries and foliage are poisonous to livestock.
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Description
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Silverleaf Nightshade is a
perennial that grows up to 3
feet tall. Leaves are lance shaped, somewhat wavy along the edges, an inch
or less in width, and up to 5 inches long. Stems are armed with a few
yellowish thorns. Both stems and leaves are covered with downy hairs, giving
the plant a silvery appearance. Flowers are about 1 inch wide with 5 bluish
to lavender or occasionally white petals, surrounding 5 bright yellow
anthers clustered in the center. Flowers bloom from midsummer until frost.
Fruits are smooth, orange-yellow to dark colored, many- seeded berries. The
plant has extensive horizontal rhizomes from the crown.
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Distribution
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 Silverleaf nightshade is found throughout the central U.S.
and occasionally in the West. Idaho infestations are noted in the map at
left. |
Control
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Herbicides ate registered for control of silverleaf
nightshade. No biological control agents are available for Idaho.
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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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