Thermopsis rhombifolia var. divaricarpa (A.Nelson) Isely

Taxonomy and Distribution

This flowering plant is a variety of Thermopsis rhombifolia, which is also commonly called prairie thermopsis. It belongs to the legume family and is native to North America, where it occurs across the Great Plains and extends into the lower canyons of the Rocky Mountains.

Natural Habitat

Its natural habitat consists of dry grasslands and woodlands.

Growth and Flowering

It is a perennial herb that produces yellow flowers during the spring.

Alkaloid Content

T. rhombifolia contains multiple quinolizidine alkaloids: anagyrine, thermopsine, rhombifoline, cytisine, N-methylcytisine, 5,6-dehydrolupanine, and lupanine. Alkaloid content is highest in the plant's seeds.

Seed Poisoning Case 1

Documented poisoning cases from ingestion of this plant include the following events: After eating a handful of the plant's immature seeds, called "peas", a 6-year-old girl developed a headache 6–7 hours after ingestion. The headache lasted for 12 hours, and she also experienced mild vomiting.

Seed Poisoning Case 2

Another 6-year-old boy ate an unknown number of these peas, started vomiting about 4 hours after ingestion, had mild vomiting that persisted for 2 hours, and experienced nausea but no headache.

Seed Poisoning Case 3

In an additional case, an 8-year-old boy ate approximately 6 peas, began vomiting 3–4 hours after ingestion, and reported abdominal cramping and headache. Most of his vomiting happened in the first few hours, and his symptoms gradually went away over the following 24 hours.

Severe Flower Poisoning Onset

One 6-year-old boy ate 20 or more of the plant's flowers, and developed abdominal pain and cramps after about 45 minutes. He vomited 6–7 times over the next 8 hours. Within an hour of ingestion, he became drowsy and weak, and had multiple episodes of dizziness and stumbling that continued over the first few hours.

Severe Flower Poisoning Outcomes

After 4 hours, he developed a headache that lasted 10–12 hours. His blood pressure and heart rate were not significantly affected, and he was treated with activated charcoal.

Mild Flower Poisoning Case

In a separate case, a 6-year-old girl ate 2–3 flowers, and developed nausea and lethargy within an hour. Her symptoms faded over the next 3–4 hours.