Thermopsis barbata

The toxicity of T. rhombifolia and T. montana has been the subject of research. The toxicity is known to come from a series of alpha-pyridone quinolizidine alkaloids, including (in decreasing order of relative abundance in plant tissues) anagyrine, thermposine, 5,6-dehydrolupanine, cytisine, N-methylcystisine, lupanine, and 17-oxysparteine. Their concentration is highest in young plants, flowers, and legumes, though otherwise generally alkaloid concentrations are equal throughout the plant. Alkaloid dosage from plant ingestion is in the range of 1.1–11.3 mg/kg. A 1997 review found 23 cases. 18 patients developed symptoms within a few hours and symptoms lasted up to 12 hours, including vomiting, dizziness, abdominal pain, drowsiness, nausea, headache, oral irritation, tachycardia, tremors, and other general signs. Only 2 required admission to a health care facility, one of which involved elevated CK levels. Purified alkaloids cause the same signs of intoxication as the whole plant.