Cottongrass – Alaska Cotton – Eriophorum

Alaska Wildflowers | White

Cottongrass (Alaska cotton)

Genus: Eriophorum L.

15 Species native to Alaska
Full list below

Common Names

Alaska cotton*
cottongrass

*I use Alaska cotton in the title here because it is the only name I have heard it called in Alaska. The actual common name is just cottongrass, as many species have a widespread distribution in the northern hemisphere.

Family: Cyperaceae/Sedge
Order: Poales
full classification

Duration – Growth Habit

Perennial – Graminoid (grass-like)

Uses

The stem and root are edible. Eriophorum angustifolium has the most record of being used as food by native tribes. The roots sometimes being boiled or eaten raw. Stem fried in seal oil or roots stored in seal oil. Yupik traditionally used an extract from the leaves for medicinal purposes to treat gastrointestinal problems.

Identification

Flower: Seed heads cotton-like fibers or bristles (pappi), white to reddish-brown in color. Some species may have multiple flower heads, some are singular.
Leaves: grass-like, slender, v-shaped
Stem: Erect, tall

Most species are between 30-60 cm (12-24 in) tall with a drooping head of cotton that is whitish in color. The cotton fibers release in the wind to disperse seeds. Alaska cotton typically grows in the tundra on tussocks or in boggy areas, or near water where there is wet soil.

Eriophorum is a perennial herb that grows either in clumps or on its own, thanks to its underground stems called rhizomes. The stem can be either triangular or round, and the plant can have leaves at the base and along the stem. Sometimes the leaves along the stem might be sheaths without blades. The leaves are long, thin, and can be up to 25 cm long and 2.5-4 mm wide, with a thread-like tip.

The flowers of the Eriophorum plant grow at the top of the stem, either as single spikelets or in a small cluster of 2-10 (sometimes up to 30) that forms a head-like or umbrella-like shape. There can be one or more bracts (modified leaves) at the base of the flower cluster that looks like regular leaves or smaller, scale-like structures.

Each spikelet has 20-200 scales arranged in a spiral, with a flower underneath each scale. The flowers have male and female parts, surrounded by 10-25 very thin, smooth bristles that are much longer than the seed (achene) they protect. These bristles can make it difficult to see the individual scales. The flowers also have 1-3 stamens (the male parts) and a style (the female part) that splits into three sections and eventually falls off. The seeds produced by the Eriophorum plant are triangular.

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Distribution and Habitat

Eriophorum is found across the Northern Hemisphere in cool temperate, alpine, and arctic regions.

There are 18 species of cottongrass in the world and 15 of these are native to Alaska. Out of the 15 species of Alaska cotton, the most common is Tall Cotton Grass (Eriophorum angustifolium), which is also the most common cottongrass found throughout the world. Hikers are very familiar with the Tall Cotton Grass that grows on deep round tussocks and make it all too easy to roll an ankle.

Species Found In Alaska

Eriophorum angustifolium (tall cottongrass, narrowleaf cottonsedge)
Eriophorum beringianum (Bering cottongrass)
Eriophorum brachyantherum (northland cottonsedge)
Eriophorum callitrix (arctic cottongrass, arctic cottonsedge)
Eriophorum chamissonis (Chamisso’s cottongrass)
Eriophorum churchillianum (Churchill cottongrass)
Eriophorum gracile (slender cottonsedge)
Eriophorum medium (medium cottongrass)*
Eriophorum porsildii (Porsild’s cottongrass)
Eriophorum pylaieanum (cottongrass)
Eriophorum rousseauianum (Rousseau’s cottongrass)
Eriophorum russeolum (red cottongrass)
Eriophorum scheuchzeri (white cottongrass, dense cottongrass)
Eriophorum vaginatum (tussock cottongrass)
Eriophorum viridicarinatum (thinleaf cottonsedge, tassel cottongrass)

*Listed by the Integrated Taxonomic Information Center, but not the USDA as native to Alaska

Classification

References and Further Reading

Field Guide to Alaskan Wildflowers, Pratt, Verna E. pg 63
Grasses, National Park Service: Bering Land Bridge
Eriophorum L., ITIS Report
Eriophorum angustifolium, Wikipedia
State Search Eriophorum, USDA
eriophorum search result, Native American Ethnobotony Database (September 2020)