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Reed Sweet-grass

Glyceria maxima

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Plant Profile

Flowering Months:
Poaceae (Grass)
Also in this family:
Alpine Catstail, Alpine Foxtail, Alpine Meadow-grass, Annual Beard-grass, Annual Meadow-grass, Arrow Bamboo, Barren Brome Grass, Bearded Couch Grass, Bearded Fescue, Bermuda Grass, Black Bent, Black Grass, Blue Fescue, Blue Moor-grass, Bog Hair-grass, Borrer's Saltmarsh Grass, Bread Wheat, Bristle Bent, Brown Bent, Brown Sedge, Bulbous Foxtail, Bulbous Meadow-grass, California Brome Grass, Canary Grass, Carnation Sedge, Cocksfoot, Cockspur, Common Bent, Common Cord-grass, Common Millet, Common Reed, Common Saltmarsh Grass, Compact Brome Grass, Corn, Couch Grass, Creeping Bent, Creeping Soft-grass, Crested Dog's-tail, Crested Hair-grass, Cultivated Oat, Curved Hard Grass, Cut Grass, Dense Silky Bent, Downy Oat-grass, Drooping Brome Grass, Drooping Tor Grass, Dune Fescue, Early Hair-grass, Early Meadow-grass, Early Sand-grass, False Brome Grass, False Oat-grass, Fern Grass, Fine-leaved Sheep's Fescue, Flattened Meadow-grass, Floating Sweet-grass, Foxtail Barley, French Oat, Giant Fescue, Glaucous Meadow-grass, Great Brome Grass, Greater Quaking Grass, Grey Hair-grass, Hairy Brome Grass, Hairy Finger-grass, Hard Fescue, Hard Grass, Harestail Grass, Heath Grass, Holy Grass, Hybrid Marram Grass, Italian Rye Grass, Knotroot Bristlegrass, Lesser Hairy Brome Grass, Lesser Quaking Grass, Loose Silky Bent, Lyme Grass, Marram Grass, Marsh Foxtail, Mat Grass, Mat-grass Fescue, Meadow Barley, Meadow Fescue, Meadow Foxtail, Meadow Oat-grass, Mountain Melick, Narrow-leaved Meadow-grass, Narrow-leaved Small-reed, Neglected Couch Grass, Nit Grass, Orange Foxtail, Pampas Grass, Perennial Rye Grass, Plicate Sweet-grass, Purple Moor-grass, Purple Small-reed, Purple-stem Catstail, Quaking Grass, Ratstail Fescue, Red Fescue, Reed Canary Grass, Reflexed Saltmarsh Grass, Rescue Grass, Rough Meadow-grass, Rush-leaved Fescue, Sand Catstail, Sand Couch Grass, Scandinavian Small-reed, Scottish Small-reed, Sea Barley, Sea Couch Grass, Sea Fern Grass, Sheep's Fescue, Silver Hair-grass, Six-rowed Barley, Slender Brome Grass, Small Cord-grass, Small Sweet-grass, Smaller Catstail, Smooth Brome Grass, Smooth Cord-grass, Smooth Finger-grass, Smooth Meadow-grass, Soft Brome Grass, Somerset Hair-grass, Sorghum, Spreading Meadow-grass, Squirreltail Fescue, Stiff Brome Grass, Stiff Saltmarsh Grass, Sweet Vernal Grass, Tall Fescue, Timothy Grass, Tor Grass, Tufted Hair-grass, Two-rowed Barley, Upright Brome Grass, Velvet Bent, Viviparous Fescue, Wall Barley, Wavy Hair-grass, Wavy Meadow-grass, Whorl Grass, Wild Oat, Wood Barley, Wood Fescue, Wood Meadow-grass, Wood Melick, Wood Millet, Yellow Oat-grass, Yorkshire Fog
Life Cycle:
Maximum Size:
3 metres tall
Ditches, gardens, grassland, marshes, ponds, riverbanks, riversides, swamps, water, waterside, wetland.

Green, no petals
Flowerheads are spreading and erect. They consist of many branches, each ending in a green, narrow, oval spikelet.
The fruit is a caryopsis, as with all species of grass.
An aquatic grass which has long, linear, bright green leaves, up to 1.8cm wide. Short but sharply pointed ligules. Perennial.
Other Names:
Greater Sweet Grass, Manna Grass, Reed Grass, Reed Mannagrass, Reed Meadow Grass, Tall Mannagrass.
Frequency (UK):

Similar Species

Other Information


Glyceria maxima, commonly known as reed sweetgrass or tall mannagrass, is a species of grass in the Poaceae family. It is native to Europe, Asia, and North America, and can be found in wetland habitats such as marshes, swamps, and along the banks of streams and rivers. The plant can grow to be quite tall, up to 3m in height, and has long, narrow leaves and spikes of greenish-purple flowers. G. maxima is commonly used as a forage crop for livestock, as well as for erosion control and as a decorative plant in gardens.


Reed sweet-grass, scientifically known as Glyceria maxima, is a perennial grass species that is native to wetlands, marshes, and meadows throughout Eurasia and North America. The plant is also commonly referred to as tall mannagrass, reed grass, or reed meadow grass. Reed sweet-grass is an important plant species in wetland ecosystems, providing both habitat and food for a variety of animal species.

Appearance and Characteristics

Reed sweet-grass is a tall, robust plant, growing up to 10 feet (3 meters) tall, with a thick, sturdy stem that can reach up to 1 inch (2.5 cm) in diameter. The leaves are long, narrow, and flat, with a prominent midrib, and are usually about 1 inch (2.5 cm) wide. The flowers are arranged in large, dense panicles at the top of the stem, with each flower having two small, greenish-yellow florets. The plant blooms from June to August and produces a profusion of seeds, which are dispersed by the wind.

Ecological Importance

Reed sweet-grass is a keystone species in wetland ecosystems, providing habitat and food for a variety of animal species. Its tall, dense growth provides shelter and nesting sites for waterfowl, marsh birds, and other wetland animals. The plant also plays a crucial role in stabilizing wetland soils, preventing erosion, and filtering pollutants from the water.

Cultural Significance

Reed sweet-grass has been used by humans for a variety of purposes throughout history. In traditional medicine, the plant has been used to treat a variety of ailments, including fever, diarrhea, and dysentery. The fibrous stems of the plant have also been used for weaving baskets, mats, and other household items. In some cultures, reed sweet-grass has been used for thatching roofs and making wattle and daub walls.

Conservation Status

Reed sweet-grass is a common and widespread species, but its populations are threatened by habitat loss and degradation. Wetland habitats are under increasing pressure from development, agriculture, and other human activities, which can lead to the destruction of the plant's habitat. Conservation efforts aimed at protecting and restoring wetlands are critical for the long-term survival of reed sweet-grass and the many other plant and animal species that depend on wetland ecosystems.

Reed sweet-grass is a fascinating plant with important ecological and cultural significance. Its tall growth, ability to stabilize wetland soils, and provide habitat and food for a variety of animal species make it a vital component of wetland ecosystems. Efforts to protect and restore wetlands are critical for the long-term survival of this important plant species and the many other species that depend on wetland habitats for their survival.

More Information

Reed sweet-grass is a highly adaptable species that can tolerate a wide range of environmental conditions, including waterlogged soils and areas with high salinity. In fact, it is often found growing in brackish marshes and along the banks of tidal rivers and estuaries. The plant is also resistant to grazing by livestock, making it an important food source for wetland wildlife.

One of the unique characteristics of reed sweet-grass is its ability to store large amounts of carbon in the soil. Wetland ecosystems are known for their high carbon sequestration potential, and reed sweet-grass plays a significant role in this process. As the plant grows, it stores carbon in its tissues, and when it dies, the carbon is released into the soil, where it can be stored for centuries or even millennia.

In addition to its ecological and cultural significance, reed sweet-grass has also been studied for its potential economic value. The plant contains high levels of cellulose and hemicellulose, making it a potential source of bioenergy. Research has shown that reed sweet-grass can be converted into ethanol, biogas, and other biofuels, making it a promising candidate for sustainable energy production.

Overall, reed sweet-grass is a fascinating plant with a rich history and important ecological and economic significance. Its ability to thrive in wetland habitats, provide habitat and food for a variety of animal species, and store large amounts of carbon in the soil make it a crucial component of wetland ecosystems. As wetland habitats continue to be threatened by human activities, conservation efforts aimed at protecting and restoring these important ecosystems are more important than ever.

Reed sweet-grass also has a role in phytoremediation, a process that uses plants to remove pollutants from the soil or water. The plant is known to accumulate heavy metals, such as lead and cadmium, from the soil and store them in its tissues. This ability to tolerate and accumulate pollutants makes reed sweet-grass a potential candidate for the remediation of contaminated sites.

Reed sweet-grass is not only an important species for the ecology and the economy, but it also has some cultural and spiritual significance. In some indigenous cultures, the plant is considered a sacred plant, and its use in ceremonies and rituals dates back centuries. For example, the Tlingit people of the Pacific Northwest traditionally use reed sweet-grass in basket weaving and other crafts, and it is often featured in their artwork.

Reed sweet-grass is a versatile and important plant species with many ecological, economic, and cultural values. As wetlands face increasing pressures from human activities and climate change, it is important to recognize and protect the vital roles that reed sweet-grass and other wetland species play in maintaining the health of these important ecosystems. By understanding and appreciating the many values of reed sweet-grass, we can work towards ensuring its conservation and sustainable use for future generations.

Reed sweet-grass is a highly productive plant species that can grow rapidly, producing up to 10 tons of dry matter per hectare per year. This high productivity makes it a potential source of feed and forage for livestock. In some areas, reed sweet-grass is cultivated as a forage crop, providing a valuable source of feed for dairy and beef cattle, sheep, and other livestock.

The plant's ability to tolerate and thrive in wetland habitats also makes it an important tool for wetland restoration and management. Restoring wetlands that have been degraded or destroyed can be a challenging and costly process, and using native plant species like reed sweet-grass can help to speed up the process and reduce costs. Planting reed sweet-grass and other native wetland species can help to stabilize soil, reduce erosion, filter pollutants, and provide habitat and food for wetland wildlife.

In addition to its ecological and economic benefits, reed sweet-grass is also valued for its aesthetic qualities. The tall, graceful stems and delicate flowers of the plant make it a popular choice for ornamental gardening and landscaping. It is often used in water gardens, ponds, and other aquatic environments, adding beauty and texture to these spaces.

Overall, reed sweet-grass is a versatile and valuable plant species that has many important ecological, economic, and cultural values. Its ability to thrive in wetland habitats, provide food and habitat for wildlife, store carbon in the soil, and be used for phytoremediation, bioenergy production, and wetland restoration make it a valuable resource for sustainable development. As we continue to face environmental challenges and work towards a more sustainable future, reed sweet-grass and other wetland species will play a crucial role in the conservation and management of these important ecosystems.

Distribution Map

Reproduced by kind permission of the BSBI.

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