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Panicum virgatum

Authority	L.
Family	Liliopsida:Commelinidae:Cyperales:Gramineae
Synonyms	Panicum virgatum var. virgatum L.
Common names	blackbent, lowland switchgrass, Switchgrass, tall panic grass, tall prairie grass, thatch grass, wild redtop, Wobsqua grass
Editor
Ecocrop code	8289

Notes
DESCRIPTION: A hardy, perennial rhizomatous caespitose grass; which begins growth in late spring. It can grow up to 1.8-2.2 m in height; rhizomes elongated; scaly. Culms 60-300 cm long. Culm nodes glabrous, or bearded. Lateral branches lacking. Leaf-sheaths glabrous on surface. Ligule a ciliolate membrane; 1.5-3 mm long. Leaf-blades 10-60 cm long; 3-15 mm wide. Leaf-blade surface glabrous, or pilose. Foliage - tinged with red. Inflorescence an open ovate panicle15-55 cm long. Spikelets solitary. Fertile spikelets pedicelled. Spikelets comprising 1 basal sterile florets; 1 fertile floret; without rhachilla extension. Spikelets ovate; dorsally compressed; 3-5 mm long; falling entire. Glumes reaching apex of florets; thinner than fertile lemma. Lower glume ovate; clasping; 0.66-0.75 times length of spikelet; membranous; without keels; 5 -veined. Lower glume apex acuminate. Upper glume ovate; 1 times length of spikelet; membranous; without keels; 7-veined. Upper glume apex acuminate. Basal sterile florets male; with palea. Lemma of lower sterile floret similar to upper glume; ovate; 1 times length of spikelet; membranous; 5 -veined; acuminate. Fertile lemma ovate; dorsally compressed; 2.5-3.5 mm long; indurate; pallid; shiny; without keel. Lemma margins involute. Lemma apex acute. Palea involute; indurate. Anthers 3. Fruit is a caryopsis with an adherent pericarp. USES: It is a cultivated range and fodder grass and is grazed by certain animals, used as ground cover to control erosion and farmed as forage for livestock. As a drought resistant ornamental grass, it is easily grown in average to wet soils and in full sun to part shade. Establishment is recommended in the spring, at the same time as maize is planted. It can also be used for silage and as an energy substitute and is often considered a good candidate for bio-fuel, especially ethanol fuel production, due to its hardiness against poor soil and climate conditions, rapid growth and low fertilization and herbicide requirements. It has the potential to produce the biomass required for production of up to 380 liters of ethanol per metric ton. This gives it the potential to produce over 400 liters of ethanol per hectare, compared to 270 for sugarcane and 160 for corn. However, there is debate on the viability of switchgrass, and other bio-fuels, as an efficient energy source. University of California, Berkeley professor Tad Patzek argues that switchgrass has a negative ethanol fuel energy balance, requiring 45 percent more fossil energy than the fuel produced. GROWING PERIOD: Perennial; warm season; sod forming; slow spreader. FURTHER INF.: Switchgrass uses C4 carbon fixation, giving it an advantage in conditions of drought and high temperature. As an open pollinated species, switchgrass expresses tremendous genetic diversity, with wide variations in its basic chromosome number (2n = 18), typically ranging from tetraploid to octoploid. Morphologically switchgrass in its southern range can grow to more than 3 m in height, but what is most distinctive is the deep, vigorous root system, which may extend to depths of more than 3.5 m. It reproduces both by seeds and vegetatively and, with its perennial life form, a stand can last indefinitely once established. Standing biomass in root systems may exceed that found aboveground, giving perennial grasses such as switchgrass, an advantage in water and nutrient aquisition even under stressful growing conditions. Distribution; Asia-temperate: Soviet Middle Asia and China. Pacific: north-central. North America: western Canada, eastern Canada, northwest USA, north-central USA, northeast USA, southwest USA, south-central USA, southeast USA, and Mexico. South America: Mesoamericana, Caribbean, and Brazil.
Sources
USDA Plants profile (Switchgrass) Developing Switchgrass as a Bioenergy Crop (NewCrop) Switchgrass (Wikipedia) Roecklein J 1987 pp 185 [USE, TEXT, LIG] Duke J 1979 pp 95 [PH, RAIN, TEMP] Heath M 1985 pp 183-184 [TEXT, FER, USE] Kernick M 1961 pp 38 [PHO] Duke J 1975 pp 23 [PH, RAIN, TEMP] Clayton, Harman & Williamson 2006. Royal Botanic Gardens, Kew [TEXT]