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Knotroot Bristlegrass

Setaria parviflora

Please keep in mind that it is illegal to uproot a plant without the landowner's consent and care should be taken at all times not to damage wild plants. Wild plants should never be picked for pleasure and some plants are protected by law.
For more information please download the BSBI Code of Conduct PDF document.


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, 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, Reed Sweet-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:
120 centimetres tall
Grassland, saltmarshes, wasteland, wetland.

Green, no petals
Compact green spike reaching a maximum of 10cm in length, each spikelet is surrounded by yellowish-purple bristles. Flowers in my opinion look like hairy caterpillars.
Oval seeds in autumn and early winter.
The stiff, flat leaf blades are up to 25cm long and no wider than 1cm.
Other Names:
Bent Pigeon Grass, Bristly Foxtail, Knotroot Foxtail, Marsh Bristlegrass, Perennial Foxtail, Slender Pigeon Grass, Small-flower Brittlegrass, Small-flower Foxtail, Small-flowered Pigeon Grass, Yellow Bristlegrass, Yellow Foxtail.
Frequency (UK):

Other Information


Setaria parviflora, also known as smallflower bristlegrass or smallflower foxtail, is a species of grass native to North America. It is an annual grass that grows to about 1 meter in height and has thin, wiry stems with small, green leaves and short, dense spikes of flowers. It is commonly found in fields, pastures, and other grassy areas, and is often considered a weed due to its ability to spread quickly and compete with other plants for resources. It is tolerant of a wide range of soil types and growing conditions and is resistant to drought.

Knotroot Brittlegrass: An Overview of Setaria parviflora

Knotroot brittlegrass, also known as Setaria parviflora, is a species of grass that is commonly found in various regions of the world including Asia, Africa, Australia, and the Pacific islands. This grass species is known for its small size and delicate appearance, making it an attractive option for landscaping and ornamental gardens.

Biology and Characteristics of Knotroot Brittlegrass

Setaria parviflora is an annual plant that grows to a height of 30-70 cm. It is a delicate species that is characterized by its thin and erect stems, which are often light green in color. The leaves of knotroot brittlegrass are linear in shape and grow to a length of 2-10 cm. The leaves are also relatively thin, with a width of 2-4 mm.

One of the most distinctive features of knotroot brittlegrass is the knot-like structure at the base of the stems, which gives the plant its name. These knots serve as a storage organ for the plant and allow it to survive in harsh conditions.

In terms of reproduction, knotroot brittlegrass produces small, spherical inflorescences that contain several flowers. The flowers are usually light green in color and produce small, light brown seeds that are dispersed by the wind.

Ecology and Uses of Knotroot Brittlegrass

Knotroot brittlegrass is a hardy species that is well adapted to various types of habitats, including forests, grasslands, and wetlands. It is often found growing in disturbed areas, such as roadsides and agricultural fields, and can thrive in a range of soils, including those that are poor in quality.

In addition to its ornamental value, knotroot brittlegrass is also valued for its ecological benefits. It provides food and habitat for various species of birds and insects, and can also help to prevent soil erosion.


Knotroot brittlegrass is a fascinating species of grass that is known for its delicate appearance and hardiness. Whether you are a gardener, an ecologist, or simply someone who appreciates the beauty of nature, Setaria parviflora is well worth considering for your next project. With its ability to adapt to a range of conditions and provide important ecological benefits, knotroot brittlegrass is a valuable species that deserves more recognition and attention.


In terms of human uses, knotroot brittlegrass has a number of practical applications. For example, it is used as a forage crop for livestock, providing a source of nutrition for grazing animals. In some regions, the seeds of knotroot brittlegrass are also harvested for human consumption, either as a staple food or as an ingredient in traditional dishes.

In addition to its practical uses, knotroot brittlegrass is also of scientific interest, as it is a model species for studying the evolution and ecology of grasses. Scientists have been studying the genetics, morphology, and behavior of this grass species in order to gain a better understanding of the evolution of the Poaceae family, which includes some of the most important crops in the world, such as rice, wheat, and maize.

However, despite its many positive attributes, knotroot brittlegrass can also be considered a weed in some situations. It can be difficult to control and can quickly spread in agricultural fields, making it a nuisance for farmers. For this reason, it is important to carefully consider the impact that knotroot brittlegrass can have on the environment and agriculture before planting it in a new area.

It's worth mentioning that knotroot brittlegrass is a fast-growing species, which makes it an attractive option for greening up areas quickly. Its quick growth and ability to thrive in a range of conditions make it a popular choice for reforestation projects, erosion control, and other land restoration efforts.

However, its fast growth can also be a double-edged sword. In areas where it is not native, knotroot brittlegrass can quickly become invasive, outcompeting native plants and altering the ecosystem. For this reason, it is important to be mindful of the potential impacts that knotroot brittlegrass can have when planting it in a new area.

In terms of cultivation, knotroot brittlegrass is relatively easy to grow, and can be propagated from seed. It is tolerant of a wide range of soils and can grow in both sunny and shaded areas, making it a versatile choice for landscaping and gardening.

In terms of its potential as a crop, knotroot brittlegrass is a promising species that has been the subject of a great deal of research in recent years. Scientists have been exploring its potential as a biofuel crop, as well as its nutritional value for both humans and livestock. In addition, there is interest in developing knotroot brittlegrass as a new source of bioenergy, as it has a high yield of biomass and is easy to grow.

In conclusion, knotroot brittlegrass is a fascinating species that has a range of benefits and uses, from its ornamental value to its potential as a bioenergy crop. While it is important to be mindful of its potential to become invasive, knotroot brittlegrass is a species that has much to offer and is well worth exploring.

Distribution Map

Reproduced by kind permission of the BSBI.

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