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Alaska Wildflowers | Pink

Alpine sweetvetch

Hedysarum alpinum

Common Names:
Alpine sweetvetch
Wild potato
Eskimo potato

Genus: Hedysarum L. (sweetvetch)
Family: Fabaceae/Leguminosae (Pea family)
Order: Fabales

Duration: Perennial

Uses: Root can be eaten raw, boiled, fried, or roasted. It is typically harvested in autumn after the first frost but can be harvested until spring. Roots can be stored frozen. Other parts of the plant may be toxic, especially the seeds.

Identification

Alpine sweetvetch is a perennial herb that grows between 50-100 cm (1.5-3.25 feet) tall, although it is often much smaller in alpine areas. It has numerous, erect stems from rhizomes on a thick taproot. The leaves are 8-12 cm (3-5 inches) long, divided into 7-15 ovate-lanceolate leaflet blades that are 1.5-3 cm long. The racemes are dense, with many small (~1.5 cm), fragrant, bright pink or light purple flowers. Seeds are flat, segmented legume pods divided into 2-9 pods.

Food and Toxin

The roots of alpine sweetvetch is a primary food source for Northern Yukon and Alaska interior grizzly bears, especially in the spring [MacHutchon]. It also serves as a food source for black bears, Dall sheep, and numerous rodents.

The root is also an essential root vegetable for many Alaska Native tribes, as even in winter, the ground can be warmed by fire to dig up the root that tastes carrot-like. Inupiat store the roots in seal, fish, or bear oil for use in the winter. By storing them or digging them out over winter, they could be eaten in times of food shortage. Some arctic tribes used dogs, trained to locate mouse ‘caches’ of the root to dig out the tubers for eating.

The seeds are poisonous, especially when eaten raw. There is some evidence that the seeds of alpine sweetvetch are what poisoned Christopher McCandless, the subject of Jon Krakauer’s popular book (made into a movie), Into the Wild. However, there is no consensus if Chris died from poisoning or just starvation after two decades of debate. There is also not yet a full understanding of the level of toxicity of the seeds.

Chemical analysis on the seeds of Hedysarum alpinum in 2015 showed that they contain a toxic, nonprotein amino acid known as L-canavanine. L-canavine can induce lupus-like symptoms in humans including stiffness of the hindquarters, progressive weakness, emphysema, and hemorrhages of the lymph glands [Krakauer].

It is interesting reading the development in understanding the seed toxicity and how Krakauer wound up publishing the study on it in the journal of Wilderness & Environmental Medicine.

The original article was published in the New Yorker in 2013, where Krakauer identifies an alkaloid that was later learned not to be the correct toxin. Even though the substance wasn’t the right one (ODAP), the article lays out much of the backstory surrounding this controversy. It was Krakauer’s response to an article critical of this non-peer-reviewed “study” by Dermot Cole, a columnist with the Anchorage Daily News that led to Krakauer’s follow-up article in the New Yorker two years later and the study of the Presence of L-Canavanine in Hedysarum alpinum Seeds and Its Potential Role in the Death of Chris McCandless.

Range and Habitat

Hedysarum alpinum is widely distributed in northern hemisphere, especially in circumpolar regions. It is found in Alaska, most of Canada, some of the northern lower 48 states, and Eurasia.

Alpine sweetvetch is frequently in swampy meadows, taiga forests, stony slopes, glacial moraines, and gravel riverbeds and floodplains.

Classification

RankScientific Name (Common Name)
KingdomPlantae (Plants)
SubkingdomTracheobionta (Vascular plants)
SuperdivisionSpermatophyta (Seed plants)
DivisionMagnoliophyta (Flowering plants)
ClassMagnoliopsida (Dicotyledons)
SubclassRosidae
OrderFabales
FamilyFabaceae ⁄ Leguminosae (Pea family)
GenusHedysarum L. (sweetvetch)
SpeciesHedysarum alpinum L. (alpine sweetvetch)

References and Further Reading

Krakauer, J., Long, Y., Kolbert, A., Southard, J., (2015). Presence of L-Canavanine in Hedysarum alpinum Seeds and Its Potential Role in the Death of Chris McCandless. Wilderness & Environmental Medicine. 26, 36-42.

MacHutchon, G., Wellwood, D., (2003). Grizzly Bear Food Habits in the Northern Yukon, Canada. International Association for Bear Research and Management. Ursus. 14(2), 225-2.

Hedysarum alpinum L., Native American Ethnobotany DataBase

Field Guide to Alaskan Wildflowers, Pratt, Verna E. pg 25

Hedysarum alpinum – L., Plants For A Future

Hedysarum alpinum L. alpine sweetvetch, USDA Database

Hedysarum alpinum  L. Taxonomic Serial No.: 26723, ITIS Report Database

How Chris McCandless Died, (2013), Jon Krakauer, The New Yorker

How Chris McCandless Died: An Update, (2015), John Krakauer, The New Yorker

Hedysarum alpinum: Description from Flora of China, Efloras.org

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