tall cottongrass

LC - Least Concern

NNR - Unranked

SNR - Unranked

not listed

OBL - Obligate wetland

OBL - Obligate wetland

OBL - Obligate wetland

Tall cottongrass is a showy, early season sedge. It is native to Europe, western Asia, and North America. It occurs across the northern third of the continental United States from Maine to New York, west to Washington and Oregon, and south along the Rocky Mountains in Colorado and northern New Mexico. In Minnesota it is very common in the wetter northern half of the state, less common in the drier southern half. In the north it is found in many wet habitats, including conifer swamps, edges of marshes and lakes, fens, and ditches. In the south it is found in calcareous fens, sedge meadows, and marshy depressions in prairies. It grows under full or partial sun, usually in peaty soil but sometimes in wet, poorly drained, sandy or loamy soil. It tolerates both acidic soil in bogs and limey (calcareous) soil in fens.

Tall cottongrass is an 8″ to 40″ (20 to 100 cm) tall, erect, perennial sedge. It often forms loose colonies. Single stems (culms) rise from a long, creeping, underground, horizontal stem (rhizome). The rhizome is up to 8″ (20 cm) long.

The culms are unbranched and slender, 1⁄32″ (1.0 to 1.2 mm) in diameter near the top. They are solid and almost round in cross section.

Both basal and stem leaves are produced. Basal and lower stem leaves are up to 16″ (40 cm) long and ⅛″ to ¼″ wide. The blade is flat at the base becoming channeled and triangular in cross section just near the tip. The base of the leaf (sheath), where it wraps completely around the stem, has a dark, reddish tinged band near the top. Upper stem leaves are 1½″ to 4″ (4 to 10 cm) long and 1⁄16″ to 3⁄16″ (2.0 to 4.5 mm) wide. On the uppermost leaf the blade is much longer than the sheath.

The inflorescence is a cluster of 3 to 10 stalked spikelets at the end of the culm. Each spikelet is egg-shaped, is ⅜″ to ¾″ (10 to 20 mm) long when in flower, and is subtended by 1 to 3 modified leaves (bracts). The bracts are leaf-like, are dark red at the base, and often have a black sheath. The longest bract is ⅜″ to 4¾″ (1 to 12 cm) long, reaching to or beyond the top of the inflorescence. The central spikelet attaches to the culm without a stalk (peduncle). The remaining spikelets are on 3⁄16″ to ¼″ (5 to 6 mm) long peduncles. The longest peduncles are drooping.

Each spikelet consists of 20 to 200 overlapping, spirally arranged scales, each scale with its own flower. The scales are lance-shaped or egg-shaped, 3 ⁄16″ to ⅜″ (5 to 10 mm) long. They have a single prominent midrib that does not quite reach the tip, and no lateral ribs. They are brown to gray at the base, clear at the tip.

The flowers are minute. They have no sepals, no petals, 3 stamens, and 1 style. They have numerous hair-like bristles that elongate as the fruit matures, forming a conspicuous cottony tuft. The bristles are ⅝″ to 13⁄16″ (15 to 30 mm) long and are usually white, sometimes pale yellowish-brown.

When in fruit, spikelets are ¾″ to 2″ (20 to 50 mm) long. The fruit is a dry, black, three angled, 1⁄16″to ⅛″ (2 to 5 mm) long, seed capsule (achene) with one seed.

8″ to 40″ (20 to 100 cm)

Conifer swamps, edges of marshes and lakes, fens, sedge meadows, marshy depressions in prairies, and ditches

Late April to mid-May

Late May to early August

Sources

2, 3, 4, 5, 7, 24, 28, 29, 30, 84.

Native

One author (Kartesz, 1999) considers the attribution of Eriophorum angustifolium ssp. angustifolium to North America to be erroneous.

Common

I came across these unusual white fluffy plants at Twin Valley Prairie SNA June 8, 2023. They look like they were some kind of plant that maybe bloomed then went to seed like in the photos.

Plants

Infructescence

Location: Twin Valley Prairie SNA

I came across these unusual white fluffy plants at Twin Valley Prairie SNA June 8, 2023. They look like they were some kind of plant that maybe bloomed then went to seed like in the photos.