How to identify Cotton grass (Eriophorum angustifolium)

How to identify Cotton grass (Eriophorum angustifolium)

Cotton grass, also known as Common cottonsedge, Bog-cotton, Narrowleaf cotton-grass

Cotton grass is a perennial sedge characterized by its grass-like foliage and distinct cotton-tufted flower spikes. Its slender leaves are typically pale green and can reach lengths of up to 20 inches (50 cm). The plant’s most striking feature is its white, fluffy seed heads, resembling tufts of wool, which emerge in late spring and can persist into the fall. These seed heads are supported by triangular stems that can grow up to 3 feet (90 cm) tall. The plant thrives in moist, acidic soils and can often be found in sun-dappled to partially shaded areas.

Lifespan: Perennial

Plant Type: Herb

Leaf Type: Evergreen

Quickly Identify Cotton grass

Distinct cotton-tufted flower spikes

Fluffy white seed heads resembling tufts of wool

Triangular stems reaching up to 3 feet (90 cm) tall

Flat, triangular cross-section leaves up to 16 inches (40 cm) long

Small, brown 3-sided seeds less than 1/10th inch (2.5 mm) long

Detailed Traits of Cotton grass

Leaf Features

The leaves of cotton grass are flat, triangular in cross-section due to their sedge nature, and alternately positioned on the stem. They are between 0.08 to 0.31 inches (2 to 8 mm) wide and can grow up to 16 inches (40 cm) long. The uppermost leaf is noted for being approximately equal to or longer than its sheath. The leaves exhibit a smooth texture and a consistent green coloration, which are key characteristics for identification.

Learn About the Leaf Glossary

Flower Features

The flowers of cotton grass form clusters of spikes off the stem, initially oval and then becoming cone-shaped or fan-like as thin tassels emerge with seeds. Each flower is accompanied by a single brownish-purple scale, often with a pointed tip. The flowers lack distinctive petals, and their intricate structure aids in dispersal. They typically bloom from late spring to summer. Flower spikes range from 1 to 2 inches (2.5 to 5 cm) in length.

Learn About the Flower Glossary

Fruit Features

The fruit of cotton grass is characterized by its small, brown seeds, each measuring less than 1/10th inch (around 2.5 mm) in length, rendering them quite minute. These seeds take on a unique 3-sided shape, discernible when viewed cross-sectionally or from the downward perspective of the tip. This distinct triangular geometry, coupled with their color and size, serves as a distinguishing feature for the fruit of cotton grass.

Learn About the Fruit Glossary

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