Summary ⁸

Panicum virgatum, commonly known as switchgrass, is a perennial warm season bunchgrass native to North America, where it occurs naturally from 55°N latitude in Canada southwards into the United States and Mexico. Switchgrass is one of the dominant species of the central North American tallgrass prairie and can be found in remnant prairies, in native grass pastures, and naturalized along roadsides.

Description ⁸

Switchgrass is a hardy, deep-rooted, perennialrhizomatous grass that begins growth in late spring. It can grow up to 2.7 m (8 ft 10 in) high, but is typically shorter than big bluestem grass or indiangrass. The leaves are 30–90 cm (12–35 in) long, with a prominent midrib. Switchgrass uses C₄ carbon fixation, giving it an advantage in conditions of drought and high temperature. Its flowers have a well-developed panicle, often up to 60 cm long, and it bears a good crop of seeds. The seeds are 3–6 mm long and up to 1.5 mm wide, and are developed from a single-flowered spikelet. Both glumes are present and well developed. When ripe, the seeds sometimes take on a pink or dull-purple tinge, and turn golden brown with the foliage of the plant in the fall. Switchgrass is both a perennial and self-seeding crop, which means farmers do not have to plant and reseed after annual harvesting. Once established, a switchgrass stand can survive for ten years or longer. Unlike corn, switchgrass can grow on marginal lands and requires relatively modest levels of chemical fertilizers. Overall, it is considered a resource-efficient, low-input crop for producing bioenergy from farmland.

Distribution ⁸

Switchgrass is a versatile and adaptable plant. It can grow and even thrive in many weather conditions, lengths of growing seasons, soil types, and land conditions. Its distribution spans south of latitude 55°N from Saskatchewan to Nova Scotia, south over most of the United States east of the Rocky Mountains, and further south into Mexico. As a warm-season perennial grass, most of its growth occurs from late spring through early fall; it becomes dormant and unproductive during colder months. Thus, the productive season in its northern habitat can be as short as three months, but in the southern reaches of its habitat the growing season may be as long as eight months, around the Gulf Coast area.

In native prairies, switchgrass is historically found in association with several other important native tallgrass prairie plants, such as big bluestem, indiangrass, little bluestem, sideoats grama, eastern gamagrass, and various forbs (sunflowers, gayfeather, prairie clover, and prairie coneflower). These widely adapted tallgrass species once occupied millions of hectares.

Habitat ⁹

Much of North America, especially the prairies of the Midwestern United States, was once prime habitat to vast swaths of native grasses, including switchgrass, indiangrass (Sorghastrum nutans), eastern gamagrass (Tripsacum dactyloides), big bluestem (Andropogon gerardi), little bluestem (Schizachyrium scoparium) and others. As European settlers began spreading west across the continent, the native grasses were plowed under and the land converted to crops such as corn, wheat, and oats. Introduced grasses such as fescue, bluegrass, and orchardgrass also replaced the native grasses for use as hay and pasture for cattle.

Moth host plant ⁹

It is the preferred larval host plant of Dargida rubripennis. It is also a larval host for the Delaware skipper and the Hobomok skipper.

Read More ¹⁰

• https://www.wildflower.org/plants/result.php?id_plant=pavi2
• https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=l460
• https://www.illinoiswildflowers.info/grasses/plants/switchgrass.htm

Sources and Credits

1. (c) aarongunnar, some rights reserved (CC BY), uploaded by aarongunnar
2. (c) Don McCulley, some rights reserved (CC BY-SA), http://commons.wikimedia.org/wiki/File:Panicum_virgatum_%27Apache_rose%27_IMG_8666.jpg
3. anonymous, no known copyright restrictions (public domain), https://eol.org/media/7101314
4. (c) Tony Iwane, some rights reserved (CC BY-NC), uploaded by Tony Iwane
5. (c) Jon Hoekstra, some rights reserved (CC BY), uploaded by Jon Hoekstra
6. (c) Sean Blaney, some rights reserved (CC BY-NC), uploaded by Sean Blaney
7. (c) Sten Porse, some rights reserved (CC BY-SA), http://commons.wikimedia.org/wiki/File:Panicum-virgatum-autumn.jpg
8. Adapted by Murfreesboro,TN, Natural Resource Division from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Panicum_virgatum
9. (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Panicum_virgatum
10. (c) Murfreesboro,TN, Natural Resource Division, some rights reserved (CC BY-SA)

More Info

• iNat taxon page
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• Calflora
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• eFloras.org
• Flora of North America (beta)
• Global Biodiversity Information Facility (GBIF)
• Go Botany
• HOSTS - a Database of the World's Lepidopteran Hostplants
• IPNI (with links to POWO, WFO, and BHL)
• Jepson eFlora
• Maryland Biodiversity Project
• NatureServe Explorer 2.0
• Plants of the World Online
• SEINet Symbiota portals
• Tropicos
• USDA PLANTS database
• VASCAN by Canadensys
• World Flora Online

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