Alpine sweetvetch – Hedysarum alpinum

Alaska Wildflowers | Pink

Alpine sweetvetch

Hedysarum alpinum

Common Names

Alpine sweetvetch
Wild potato
Eskimo potato

Synonyms

Hedysarum hedysaroides
Hedysarum truncatum
Hedysarum americanum
Hedysarum philoscia
H. alpinum ssp. americanum
H. alpinum var. grandiflorum
H. alpinum var. philoscia
Hedysarum sibiricum

Subspecies

none

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

Duration – Growth Habit

Perennial – Forb/herb

Identification

Alpine sweetvetch is a pink or purple perennial herb that grows between 50-100 cm (1.5-3.25 feet) tall from a thick rhizome-like taproot (it may be much smaller in alpine areas). There are usually several decumbet-ascending or erect stems. The leaves are green, odd-pinnate, divided into 7-23 ovate-lanceolate leaflet blades that are 1.5-5 cm long. The leaflets are lanceolate to lance-elliptic and are usually sharply pointed at the tip.

The inflorescence is a dense raceme up to 20 cm long with many small, fragrant, bright pink or light purple flowers. The flowers are nodding and pea-like, 10-20 mm long. The calyx (sepals) is bell-shaped, enclosing the base of the larger corolla (petals). The keel petal is about the same length or just slightly longer than the wings. The seeds are flat, segmented legume pods divided into 2-9 segments.

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Distribution and Habitat

Hedysarum alpinum is widely distributed in the northern hemisphere, especially in circumpolar regions. It is found in Alaska, most of Canada, some of the northern lower 48 states, and Eurasia. There isn’t a huge agreement on its southern distribution, so I did not include every location on the map. NatureServe Explorer lists it as critically imperiled in Michigan and Vermont and vulnerable in Maine, Montana, and Wyoming, as well as New Brunswick and Newfoundland. GBIF lists some single occurrences in Spain, France, and the Netherlands.

The plant is frequently in swampy meadows, tundra, open forests, taiga forests, stony slopes, glacial moraines, and gravel riverbeds and floodplains. In Alaska, it is most commonly found along rocky streambeds.

Uses

For information only (typically historical) – I take no responsibility for adverse effects from the use of any plant.

The roots 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 (see below).

As a food and toxicity of seeds

The roots of alpine sweetvetch are 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 of 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].

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It is interesting reading about 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.

Classification

References and Further Reading

Uses and Toxicity

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.

H. alpinum L., Native American Ethnobotany DataBase

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

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

Guidebook

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

Classification and taxonomy

H. alpinum L. alpine sweetvetch, USDA Database

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

Distribution and Habitat

Hedysarum alpinum L. Published in: Sp. Pl.: 750 (1753), GBIF Database

Description and Information

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

H. alpinum L., Electronic Atlas of the Flora of British Columbia