Which plants are neurotoxicants associated with incoordination, depression, or agitation?

• A. Ohio buckeye or horse chestnut; locoweed; yellow star thistle; morning glory
• B. Cannabis, rayless goldenrod, sleepy grass
• C. Milkweed, Cicuta
• D. Belladonna, Datura

Answer: (A)

The question is testing which plants are classic neurotoxicants that produce central nervous system signs such as incoordination, depression, or agitation in animals. The group listed includes several well-known CNS toxins:

• Locoweed plants contain swainsonine, which disrupts brain function and leads to locoism—characterized by depression, ataxia, and poor coordination. This is a textbook example of a plant causing CNS impairment with noticeable motor and behavioral changes.

• Yellow star thistle causes nigropallidal encephalomalacia in horses, a degeneration of brain regions involved in movement. The result is marked incoordination and a characteristic inability to premasticate or prehend, along with other motor abnormalities, fitting the described CNS signs.

• Ohio buckeye (horse chestnut) seeds contain toxic constituents that can depress the central nervous system, producing ataxia and weakness in animals that ingest them.

• Morning glory seeds contain ergoline alkaloids (like lysergic acid amide) that can affect the CNS, producing agitation or other behavioral changes depending on dose.

Together, these plants are classic examples of neurotoxicants linked to the described signs, making this set the best match for the question. The other plant groups tend to cause different predominant syndromes, such as anticholinergic delirium (belladonna, Datura), seizures or severe CNS stimulation with different patterns (milkweed, Cicuta), or primarily non-neurological toxicities, which is why they’re not the best fit for the described symptom cluster.