Minidoka County, Idaho - Official Website

Home

Departments

Calendar

Photo Gallery

 
Minidoka County, Idaho - Official Website

Home

Departments

Calendar

Photo Gallery

 
[includes/nav/main.htm]

 

Home :: Weed Department :: Noxious Weeds » Poison Hemlock

Poison Hemlock
Apiaceae (= Umbelliferae), the parsnip family

Background

Poison HemlockPoison 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.

Description

Poison HemlockPoison 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.

Distribution

Poison Hemlock distribution mapIt grows throughout the U.S. except from eastern Montana to northeastern Minnesota and south to Nebraska. It has an extensive presence in Idaho.

Control

A biological control agent (a defoliating moth) provides good to excellent but inconsistent control. Herbicides are also available.

 

© 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.

 

 

 

-- Home :: Commissioners :: Departments :: Judicial ::Services ::  Links --

-- Commissioners' Proclamation --
-- Terms of Use --
--  Site Map --

©2010 Minidoka County, Idaho
- Web Site by Surf The Snake -
 

 

Home :: Weed Department :: Noxious Weeds » Yellow Starthistle

Yellow Starthistle (St. Barnaby's thistle, cotton-tip thistle)
Asteraceae (=Compositae), the aster family

Background

Yellow StarthistleYellow starthistle originated in the Mediterranean area and Asia. It spreads exclusively by seed, which may lie dormant for as long as 10 years. It causes "chewing disease" and death in horses. Yellow starthistle will grow wherever downy brome (cheat-grass) grows.

Description

Yellow starthistle is a winter annual maturing from 2 to 72 inches tall. A rosette of deeply lobed leaves up to 8 inches long forms after seed germination in the fall. Stem leaves up to 4 inches long develop in early spring, their blades forming fringelike extensions on the stem. Yellow flower heads develop at the tips of branched stems from late spring until fall. Flower head bracts bear stiff, sharp thorns 3/4 inch long. Seeds are tan with white and brown mottling, 1/8 inch long; both plumed and unplumed seeds develop in each flower head. Plumed seeds are not highly windborne; unplumed seeds not at all.

Distribution

YYellow Starthistle distribution mapellow starthistle is widely scattered throughout the U.S., but is a severe problem only in the West.

Control

Three seed head weevils and 2 seed head flies have been good to excellent biological control agents in Idaho.

© 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.

 

 

 

-- Home :: Commissioners :: Departments :: Judicial ::Services ::  Links --

-- Commissioners' Proclamation --
-- Terms of Use --
--  Site Map --

©2010 Minidoka County, Idaho
- Web Site by Surf The Snake -