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Eriophorum is a genus of herbaceous perennial flowering plants belonging to the Cyperaceae, or sedge, family. The name literally translates to wool-bearing, as it comes from the Greek word erion, which means wool or cotton, and photos, which means bearing. Eriophorum species generally look like grasses that measure 2 feet (0.61 m) to 3 feet (0.91 m) tall, with flat and leathery leaves that have fuzzy tips. These plants are more commonly known by the names cottongrass, cottonsedge, or bog-cotton, with the last common name being given due to their acid bog habitats.
The flowers are the most remarkable parts of these plants. They bloom in the months of May and June, and as they age, the fibers elongate and become more prominent, giving the appearance of small cotton heads dancing on top of the grassy leaves. Most species have white flowers, but there are some with yellow-brown or reddish flowers. There are around 25 species of Eriophorum plants scattered across the cool, temperate, and alpine regions of the northern hemisphere—from North America and northern Europe all the way to northern Eurasia. These plants generally favor wet environments in the mountains.
Natural propagation of these plants is by seed, with aid from the wind during pollination. The seeds ripen from July to August, and because they can easily be propagated, Eriophorum plants can be quite invasive. In some areas, however, there are species listed as threatened and endangered, such as E. angustifolium, or tall cottongrass; E. gracile, or slender cottongrass; and E. virginicum, or tawny cottongrass. Eriophorum plants can thrive in sandy, loamy, or clayish soils as long as it is acidic and watery. Gardeners who wish to plant these species in their gardens should plan to place them in full sun.
The traditional use of Eriophorum in Europe and North America is as stuffing for pillows and mattresses. Native Americans and colonial Americans have also used these plants to make thread. The thread from Eriophorum is not very strong, though, which is why it is blended with linen and wool to make fabric fibers both softer and more durable. Attempts to make these plants a substitute for cotton have failed because their fibers are brittle and break easily when twisted.
Aside from being a source of fiber, Eriophorum plants have also been used to make candlewicks or wicks for oil lamps. The dried leaves and stems can also be woven into soft mats. Some sources indicate that the roots, leaves, and stems are edible and may be used for medicinal purposes. An infusion of leaves and roots is believed by some to treat diarrhea, and some Native American tribes eat raw stems for good health.