A Toxic Plant That Hides in Your Hay
Jimsonweed (Datura stramonium) is one of the most toxic plants found on Texas ranches, yet it often goes unnoticed until cattle are already poisoned. Known by many names — Devil's snare, devil's trumpet, locoweed (incorrectly), thorn apple, and stinkweed — this distinctive plant contains powerful alkaloids that can cause bizarre behavior, hallucinations, and death in cattle.
Cattle usually avoid fresh jimsonweed because of its foul odor, but contaminated hay and silage are common sources of poisoning. Every Texas rancher needs to know this plant.
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Plant Identification
Physical Characteristics
- 2-5 feet tall, sometimes larger
- Bushy, spreading habit
- Strong, unpleasant odor when crushed
- Oval with irregular, pointed lobes
- Coarsely toothed margins
- Dark green upper surface, paler below
- Emit foul smell when crushed
- 3-5 inches long
- White to pale purple
- Open in evening, wilt by midday
- Fragrant (attractively so, unlike leaves)
- Golf ball to tennis ball sized
- Covered with sharp spines
- Four-chambered inside
- Contains 50-100+ seeds per pod
- Green when immature, brown when ripe
- Smooth when young
- Stout and forked branching
Similar Species to Distinguish
| Plant | Key Differences |
|---|---|
| Sacred datura (D. wrightii) | Larger flowers, perennial, South/West Texas |
| Angel's trumpet (Brugmansia) | Hanging flowers, tree-like, ornamental |
| Wild tobacco | Smaller flowers, different leaf shape |
| Nightshades | Smaller plants, smaller flowers, no spiny pods |
Toxicity Profile
The Toxins: Tropane Alkaloids
Jimsonweed contains three primary tropane alkaloids:
- Causes pupil dilation
- Increases heart rate
- Reduces secretions
- Causes fever
- Causes delirium and hallucinations
- Produces sedation at high doses
- Memory impairment
- Contributes to central nervous system effects
Toxicity by Plant Part
| Plant Part | Relative Toxicity | Notes |
|---|---|---|
| Seeds | Highest | 0.2-0.4% alkaloid content |
| Leaves | High | 0.2-0.45% alkaloid |
| Roots | High | Similar to leaves |
| Stems | Moderate | Lower concentration |
| Flowers | Moderate | Can be eaten if attractive |
Lethal Dose
- Estimated at 0.06-0.1% of body weight
- For a 1,000 lb cow: approximately 0.5-1 lb of plant material
- Seeds are particularly dangerous: a few ounces can be lethal
- Effects can occur with much smaller doses
Toxicity Retained in Hay
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Signs of Jimsonweed Poisoning
Classic Toxidrome
Jimsonweed poisoning produces a distinctive set of symptoms, sometimes summarized as:
"Hot as a hare, blind as a bat, dry as a bone, red as a beet, mad as a hatter"
Symptom Progression
- Dilated pupils (eyes appear "all black")
- Dry mouth and nose (no salivation)
- Dry, hot skin
- Increased body temperature
- Restlessness
- Bizarre behavior
- Disorientation
- Difficulty swallowing
- Bloat (inability to eructate)
- Constipation (gut motility stops)
- Staggering, incoordination
- Unusual vocalizations
- Seizures or convulsions
- Rapid, weak pulse
- Respiratory failure
- Coma
- Death
Behavioral Changes
Animals may exhibit unusual behaviors:
- Walking into fences or obstacles
- Standing in corners
- Circling
- Head pressing
- Apparent hallucinations (reacting to things not there)
- Abnormal aggression or extreme docility
- Failure to recognize familiar handlers
High-Risk Scenarios
Contaminated Hay
- Fresh jimsonweed smells bad; dried does not
- Seeds easily hidden in hay
- Cattle cannot be selective when eating baled hay
- Large amounts can be consumed before detection
- Late-season hay (after jimsonweed seeds mature)
- Hay from disturbed areas or field edges
- Drought-year hay (less grass, more weeds)
Contaminated Silage
- Jimsonweed can survive ensiling process
- Toxins remain active
- Chopped material distributes throughout silage
- Even more dangerous than hay (can't see contamination)
Fresh Plant Consumption
Less common but occurs when:
- Other forage severely limited
- Cattle accidentally consume while grazing
- Young, curious animals investigate
- Plants growing in corrals where cattle have no choice
Prevention Strategies
Field Management
- Look along fence lines and disturbed areas
- Check field edges and waterways
- Note patches for exclusion or treatment
- Or remove from rotation for that cutting
- Even a few plants can contaminate many bales
- Maintain healthy grass stands
- Minimize soil disturbance
- Mow before seed production
- Hand-pull small infestations (wear gloves—toxins can absorb through skin)
Hay Purchasing
- What weed control was used?
- Have any animals had problems with their hay?
- Can you guarantee no jimsonweed contamination?
- Look for distinctive spiny seed pods
- Check for large, lobed leaves
- Reject suspicious loads
Treatment
Emergency Response
- Separate affected animals - Prevent injury and allow observation
- Call veterinarian immediately - This is a medical emergency
- Keep animal calm - Stress worsens symptoms
- Provide shade - Overheating is a real danger
- Document symptoms - Video if possible
Veterinary Treatment
- Physostigmine - Specific antidote (reverses some effects)
- IV fluids - Support hydration
- Temperature control - Cool hyperthermied animals
- Sedation - If animal is severely agitated
- Rumen lavage - In some cases
- Supportive care - Nursing until toxin clears
Prognosis
| Situation | Prognosis |
|---|---|
| Mild symptoms, early treatment | Good |
| Moderate symptoms | Fair to good |
| Severe symptoms, delayed treatment | Guarded |
| Seizures, coma | Poor |
| Multiple animals severely affected | Variable |
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Regional Distribution in Texas
Where Jimsonweed Is Common
- Follows human activity
- Found around old homesteads
- Common in corrals, barnyards
- Roadsides and waste areas
- Field margins and fence lines
- Disturbed ground
- Full sun to partial shade
- Areas with nitrogen enrichment
Similar Species by Region
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Case Example: Hay Contamination
- Dry noses despite hot weather
- Two cows circling aimlessly
- One cow trying to walk through a fence repeatedly
- Found multiple spiny jimsonweed seed pods
- Entire load contaminated
- All three recovered over 48 hours
- Remaining hay load refused and returned
- Rancher now inspects all hay before feeding
Bottom Line
- The spiny seed pod is the giveaway - Learn to recognize it in hay
- Dried plants are just as toxic - Hay contamination is the primary threat
- Signs are distinctive - Dilated pupils, dry mouth, bizarre behavior
- Treatment exists - Physostigmine is a specific antidote; call vet immediately
- Scout hay fields before cutting - Prevention is essential
- Inspect purchased hay - Break open and check before feeding
- Control in pastures - Easy to kill with herbicides when young
- The smell is a warning - Fresh plants smell bad; cattle usually avoid
Related Resources
- Complete Guide to Texas Toxic Plants
- Hay Quality Inspection Checklist
- When to Call the Vet Flowchart
- Poisoning First Aid Protocol
References
- Burrows, G.E. & Tyrl, R.J. (2013). Toxic Plants of North America. Wiley-Blackwell.
- Texas A&M AgriLife Extension. (2024). "Jimsonweed Poisoning in Livestock."
- Knight, A.P. (2001). A Guide to Plant Poisoning of Animals in North America. Teton NewMedia.
- Plumlee, K.H. (2004). Clinical Veterinary Toxicology. Mosby.
- USDA NRCS Plants Database. (2024). Datura stramonium profile.
- Texas Veterinary Medical Diagnostic Laboratory. (2024). "Plant Poisoning Case Reports."
"The devil's in the hay bale"
