 |
Pod
Flower |
|
Antelopehorn milkweed
(Asclepias asperula)
|
Antelopehorn milkweed is an erect-stemmed plant
growing to about 15 inches tall. Leaves are narrow, lance-shaped
and about 3 inches long. The flowers are greenish with distinctive
purplish horns and are present from March to October. The fruit
is a wrinkled pod con-taining silk-tufted seeds.
Distribution and habitat
Most abundant in western Texas, this plant has also been recorded
in the northern, central and east central regions of the state.
It ranges north into Nebraska and west into southern Utah
and southeastern California. It often abounds in open pases,
along arroyos, draws, bar ditches, trails and roadsides. Regions:
1, 2,
3, 4,
5, 6,
7, 8,
9, 10.
Toxic agent
The toxic agents involved are cardiac glycosides. Antelopehorn
milkweed poisons all livestock, especially sheep. A toxic
dose is generally considered to be 1.2 percent of the animal’s
body weight in green plant material.
|
Livestock
signs
Signs of poisoning produced by most species of Asclepias differ
only in degree. They include:
• First, profound depression, weakness and
staggering
• Collapse, followed by frequent, intermittent
muscular tremors
• Labored respiration, elevated temperature
and pupil dilation
• Death after a comatose period of variable
duration
Signs appear within a few hours of ingestion of a toxic dose,
and death follows within a few days in most fatal cases.
Integrated management strategies
Animals dislike the taste of milkweeds and seldom graze
them unless they are hungry and cond to milkweed-infested
areas. Most losses are caused by overgrazing and drought.
The plant is most toxic before it matures, somewhat less
as it dries. Antelopehorn milkweed retains enough toxicity
to be dangerous in hay. Although most animals die if they
reach the convulsive stage of milkweed poisoning, some recover.
Move them to shade, keep them quiet and give them plenty
of food and water. No medicinal treatment is specified,
but sedatives, laxatives and intravenous fluids may help.
Printable
Version (PDF) 
  
|
