Panicum virgatum L. Family - Poaceae. Common Name(s) - switchgrass, prairie switchgrass, tall panic grass, water panicum, wild redtop, thatchgrass. Synonym(s)

Answer

Score

1.01

Is the species highly domesticated? (If answer is 'no' then go to question 2.01)

y

-3

1.02

Has the species become naturalized where grown?

1.03

Does the species have weedy races?

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

1

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y

1

2.04

Native or naturalized in regions with tropical or subtropical climates

y

1

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n

0

3.04

Environmental weed y = 2*multiplier (see Append 2)

3.05

Congeneric weed y = 1*multiplier (see Append 2)

y

1

4.01

Produces spines, thorns or burrs

n

0

4.02

Allelopathic

n

0

4.03

Parasitic

n

0

4.04

Unpalatable to grazing animals

n

-1

4.05

Toxic to animals

4.06

Host for recognized pests and pathogens

y

1

4.07

Causes allergies or is otherwise toxic to humans

n

0

4.08

Creates a fire hazard in natural ecosystems

y

1

4.09

Is a shade tolerant plant at some stage of its life cycle

n

0

4.10

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y

1

4.11

Climbing or smothering growth habit

n

0

4.12

Forms dense thickets

y

1

5.01

Aquatic

n

0

5.02

Grass

y

1

5.03

Nitrogen fixing woody plant

n

0

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

n

0

6.01

Evidence of substantial reproductive failure in native habitat

n

0

6.02

Produces viable seed.

y

1

6.03

Hybridizes naturally

6.04

Self-compatible or apomictic

n

-1

6.05

Requires specialist pollinators

n

0

6.06

Reproduction by vegetative fragmentation

y

1

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

2

0

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y

1

7.02

Propagules dispersed intentionally by people

y

1

7.03

Propagules likely to disperse as a produce contaminant

n

-1

7.04

Propagules adapted to wind dispersal

y

1

7.05

Propagules water dispersed

7.06

Propagules bird dispersed

7.07

Propagules dispersed by other animals (externally)

7.08

Propagules survive passage through the gut

y

1

8.01

Prolific seed production (>1000/m2)

y

1

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y

1

8.03

Well controlled by herbicides

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y

1

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

Total score:

11

Notes

Reference

1.01

Several commercial cultivars are available. (1)Based on morphology and habitat preference, switchgrass has been classified into upland and lowland ecotypes (Porter 1966). Lowland ecotypes are adapted to flood plains and are generally taller, larger in tiller diameter, and more robust than their upland counterparts (Anon. 1954; Porter 1966). The much higher dry matter (DM) yield capability of the robust lowland cultivars compared to the smaller, less robust, upland ecotype cultivars in the southern US is well documented (Anon. 1954; Porter 1966; Sladden et al. 1991). What is less well documented is the capability of cultivars for sustained high DM production, particularly lowland cultivars grown on non-alluvial soils or marginal soils, or both. In addition, very little information is available on cultivar by environment (CE) interactions for such studies, which are of major importance in selecting and developing improved switchgrass cultivars. CE interaction causes difficulty in identifying those cultivars that perform best over the range of environmental conditions to which they will be exposed (Eberhart and Russell 1966). Therefore, this study was initiated to evaluate long-term yield performance of selected commercial upland and lowland switchgrass cultivars and cultivar blends and to estimate and characterize the magnitude of CE interaction. (2)In his book, The Color Encyclopedia of Ornamental Grasses, Rick Darke, notes that self-sowing is usually minimal, but that it "can be prolific on open moist soil; this can be valuable for naturalizing, but can be a problem when attempting to maintain uniform sweeps of clonal cultivars, since seedlings often differ noticeably from parents." (3)Selections of upland types of switchgrass have been evaluated by OSU for several years. The development of hybrid progeny with substantial heterosis for increased biomass yield will ultimately result in improved hybrid cultivars for the Central and Southern United States. The PMC is in the process of assessing several improved lines along with commercially available cultivars for dry-matter potential and environmental adaptation.

(1)Fuentes, R.G. and C.M. Taliaferro. 2002. Biomass yield stability of switchgrass cultivars. p. 276–282. In: J. Janick and A. Whipkey (eds.), Trends in new crops and new uses. ASHS Press, Alexandria, VA. (2)http://www.flower-gardening-made-easy.com/Panicum-virgatum.html [15 Jan 2008] (3)http://plants.usda.gov/factsheet/pdf/fs_pavi2.pdf [15 Jan 2008]

1.02

Weak evidence for naturalization. Need better evidence. (1)P. virgatum is frequently grown as an ornamental. Hence it is likely to escape from cultivation and could occur at refuse dumps. The unique Belgian collection originates in the Vedre Valley but is doubtfully related with wool importation. (2)In Hawai`i known from a single naturalized collection made on Oahu in 1938.

(1)Verloove, F. 2001. A revision of the genus Panicum (Poaceae, Paniceae) in Belgium. Systematics and Geography of Plants 71 (1) : 53-72. (2)Wagner, W. L., D. R. Herbst and S. H. Sohmer. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu.

1.03

Possibly races or cultivars are weedy outside their natural range, but need more evidence. (1)Table 1: Non-native, invasive plant species at Midewin National Tallgrass Prairie that threaten restoration, management or health and safety...Panicum virgatum, Switch Grass: Scattered throughout site, but only common in mesic prairie remnants. Some roadside populations may be derived from non-local strains. May need to be controlled in early stages of prairie restoration. Nonlocal strains should be eradicated. (2)The U.S. native, P. virgatum, shares many traits with Miscanthus and can also produce seeds, which may give P. virgatum even greater invasive potential. Furthermore, plants native in one region can become invasive when established elsewhere. Escape from competitors and natural enemies may help explain the weedy nature of P. virgatum outside its endemic range.

(1)http://www.fs.fed.us/mntp/plan/FEIS_V2-C.pdf [15 Jan 2008] (2)Raghu, S., R. C. Anderson, C. C. Daehler, A. S. Davis, R. N. Wiedenmann, D. Simberloff and R. N. Mack. 2006. Adding Biofuels to the Invasive Species Fire? Science 313(5794): 1742.

2.01

(1)Panicum virgatum L., switchgrass, is native to all of the United States except California and the Pacific Northwest. On suitable soils, switchgrass is climatically adapted throughout the most of the United States. (2)Native Range: Central America to southern Canada

(1)http://plants.usda.gov/factsheet/pdf/fs_pavi2.pdf [11 Jan 2008] (2)http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=L460 [11 Jan 2008]

2.02

2.03

(1) Switchgrass grows south of latitude 55° N. from Saskatchewan to Nova Scotia, and south throughout most of the United States east of the Rocky Mountains. It is most abundant in the Great Plains and eastern states. (2)On suitable soils, switchgrass is climatically adapted throughout most of the United States.

(1)http://www.usask.ca/agriculture/plantsci/classes/range/panicum.html [15 Jan 2008] (2)http://plants.usda.gov/factsheet/pdf/fs_pavi2.pdf [15 Jan 2008]

2.04

(1) Switchgrass grows south of latitude 55° N. from Saskatchewan to Nova Scotia, and south throughout most of the United States east of the Rocky Mountains. It is most abundant in the Great Plains and eastern states. (2)On suitable soils, switchgrass is climatically adapted throughout most of the United States.

(1)http://plants.usda.gov/factsheet/pdf/fs_pavi2.pdf [11 Jan 2008] (2)http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=L460 [11 Jan 2008]

2.05

(1)Both in America and Europe it can be found as an ornamental plant. The grass is also found in South America and Africa where it is used as a forage crop. (2)P. virgatum is frequently grown as an ornamental. Hence i t is likely to escape from cultivation and could occur at refuse dumps. The unique Belgian collection originates in the Vedre Valley but is doubtfully related with wool importation.

(1)Elbersen, H.W. 2001. Switchgrass (Panicum virgatum L.) as an alternative energy crop in Europe. Initiation of a productivity network. Final Report FAIR 5-CT97-3701. (2)Verloove, F. 2001. A revision of the genus Panicum (Poaceae, Paniceae) in Belgium. Systematics and Geography of Plants 71(1) : 53-72.

3.01

Weak evidence for naturalization. Need better evidence. (1)P. virgatum is frequently grown as an ornamental. Hence it is likely to escape from cultivation and could occur at refuse dumps. The unique Belgian collection originates in the Vedre Valley but is doubtfully related with wool importation. (2)In Hawai`i known from a single naturalized collection made on Oahu in 1938.

(1)Verloove, F. 2001. A revision of the genus Panicum (Poaceae, Paniceae) in Belgium. Systematics and Geography of Plants 71 (1) : 53-72. (2)Wagner, W. L., D. R. Herbst and S. H. Sohmer. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu.

3.02

Not sufficient evidence. (1)Weediness: This plant may become weedy or invasive in some regions or habitats and may displace desirable vegetation if not properly managed. Please consult with your local NRCS Field Office, Cooperative Extension Service office, or state natural resource or agriculture department regarding its status and use.

(1)http://plants.usda.gov/factsheet/pdf/fs_pavi2.pdf [11 Jan 2008]

3.03

No evidence. (1)Switchgrass is a climax species of the tallgrass prairie. It is slow to establish on abandoned agricultural lands because of its limited seed dispersal distances and requirements for high soil fertility.

(1)http://www.usask.ca/agriculture/plantsci/classes/range/panicum.html [15 Jan 2008]

3.04

No evidence.

3.05

(1)We surveyed 41 sites from throughout O'ahu that had been dominated by native pili grass (Heteropogon contortus) in the late 1960s. Pili grass was absent from 14 (35%) of those sites in 1997 and had declined in abundance in most of the 27 remaining sites, relative to the late 1960s. The pili grass communities have been replaced by communities dominated by one of three African grasses: Cenchrus ciliaris (buffel grass), Pennisetum setaceum (fountain grass), or Panicum maximum (Guinea grass). Panicum maximum was often associated with the shrub Leucaena leucocephala, and Cenchrus ciliaris and Pennisetum setaceum communities showed little evidence of succession toward woody vegetation. Communities dominated by the African grasses were significantly less diverse, in terms of number of plant species, than the native pili grass-dominated communities. Observations made on other Hawaiian islands suggest that this rapid pili grass decline and replacement with alien grasses has not been limited to O'ahu. Research is needed to determine how higher-diversity native pili grass communities can be maintained in the Hawaiian Islands as a valuable natural and cultural resource.

(1)Daehler, C.C. and D. A. Carino. 1998. Recent Replacement of Native Pili Grass (Heteropogon contortus) by Invasive African Grasses in the Hawaiian Islands. Pacific Science 52(3): 220-227.

4.01

(1)HABIT Perennial; caespitose. 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.

(1)Clayton, W.D., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 15 November 2008]

4.02

(1)Known Allelopath: No

(1)http://plants.usda.gov/java/charProfile?symbol=PAVI2 [15 Jan 2008]

4.03

No evidence.

4.04

(1)Uses Livestock: Switchgrass is noted for its heavy growth during late spring and early summer. It provides good warm-season pasture and high quality hay for livestock. (2)Usage: Switchgrass provides good forage for cows, horses, and sheep in the spring and early summer, but nutrient content declines and the leaves become too coarse and tough to be palatable later in the season after the seedheads develop. (3)Switchgrass is palatable and is readily grazed by cattle, horses and sheep during the spring and early summer before the leaves become coarse and tough

(1)http://plants.usda.gov/factsheet/pdf/fs_pavi2.pdf [11 Jan 2008] (2)http://www.floridata.com/ref/P/pani_vir.cfm [11 Jan 2008] (3)http://www.usask.ca/agriculture/plantsci/classes/range/panicum.html [15 Jan 2008]

4.05

Possibly. (1)Toxicity: None (2)Grazing switchgrass can cause photosensitization in weaned and suckling lambs. Phylloeythrin, a photo-dynamic compound, is derived from the chlorophyll by microbial action in the digestive tract. The excretion of phylloeythrin is hindered by Bilirubin and Creatinine, toxins found in the plant, causing the photosensitization effect. (3)Technical Abstract: Switchgrass (Panicum virgatum) commonly used in pastures and as a cover crop, can poisons animals similar to Kleingrass. However, switchgrass toxicity has been difficult to reproduce experimentally. The purpose of this study is to establish a model for switchgrass toxicity, identify switchgrass toxins and determine their toxicity, document the clinical and histologic lesions of switchgrass poisoning, and predict when and under what conditions switchgrass is toxic to livestock. Syrian hamsters, horses, sheep, goats and horses were fed or dosed orally with fresh switchgrass, switchgrass hay or ground switchgrass. Feeding trials varied from 30 to 180 days. Ground switchgrass was analyzed for glycosisidic steroidal alkaloids. Diosgenin was identified as the major sapogenin with smaller amounts of yamogenin. Animals fed switchgrass lost weight and body condition, but did not develop photosensitivity. No crystalline lesions were detected in the livers of these animals. However, goats fed green switchgrass with green alfalfa did develop hepatocellular necrosis with rare canilicular crystalline inclusions and radiation induced dermatitis consistent with phylloerythrin-associated photosensitivity. These findings suggest that switchgrass can be toxic under certain conditions and that goats may be most susceptible to poisoning. Additional research is needed to better define when and under what conditions poisonings are likely to occur.

(1)http://plants.usda.gov/java/charProfile?symbol=PAVI2 (2)http://www.usask.ca/agriculture/plantsci/classes/range/panicum.html [15 Jan 2008] (3)Stegelmeier, B.L., Elmore, S.A., Lee, S.T., James, L.F., Gardner, D.R., Panter, K.E., Ralphs, M.H., Pfister, J.A. 2007. Switchgrass (panicum virgatum) toxicity in rodents, sheep, goats and horses. Poisonous Plants Global Research and Solutions, Chpt. 19,pp. 113 - 117.

4.06

(1)Pests and Potential Problems: Grasshoppers and leafhoppers can be major pests in new seedings. Some stands are impacted by damping off and seedling blight. Leaf rust occasionally affects forage quality. (2)Panicum mosaic virus Described by Still in 1957 (79, 82). Causes yellow-green mosaic, mottling, chlorosis, and stunting of Panicum miliaceum, Setaria italica, and some other grasses including the native perennial Panicum virgatum in Kansas. Maize chlorotic mottle Described by Hebert & Castillo in 1973 (37a). Particles isometric to 30 nm diam. Does not react with antisera to several known viruses with similar particles. Causes chlorotic mottling, stunting, malformation of ears, and yield reduction of maize in. Peru. Also infects Euchlaena mexicana, Panicum virgatum, Sorghum halepense, S. vulgate, Setaria glauca, Bromus ar~ensis, and Triticum aestivum. (3)Pathogens: Known natural viruses: Panicum mosaic satellivirus; Panicum mosaic sobemovirus; Sugarcane mosaic potyvirus. Experimental host of: Guinea grass

(1)http://plants.usda.gov/factsheet/pdf/fs_pavi2.pdf [11 Jan 2008] (2)Slykhuis, J. T. 1976. Virus and Virus-Like Diseases of Cereal Crops. Annual Review of Phytopathology 14: 189-210. (3)Harris, A., Small, N., A. J. Gibbs, M. J.Gibbs and C. Weiller. 2000. Viruses, Phytoplasmas and Spiroplasmas of Clonal Grasses and Their Diagnosis. Plant Biosecurity, Biosecurity Australia. http://www.daff.gov.au/__data/assets/pdf_file/0003/24762/consul_rpt_clonal.pdf

4.07

No evidence (well studied species). (1)Toxicity Potential: NONE KNOWN

(1)http://tpid.tpwd.state.tx.us/species_report.asp?species=4 [16 Jan 2008]

4.08

Fire-adapted grass (1)IMMEDIATE FIRE EFFECT ON PLANT : Fire removes aboveground parts of switchgrass. Switchgrass litter is resistant to matting down. This standing dead material is apparently a good fuel source which readily carries fire.

(1)Uchytil, Ronald J. 1993. Panicum virgatum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [2008, January 15].

4.09

(1)Generally best in full sun. Will grow in part shade, but begins to lose its columnar form in too much shade, growing more openly and possibly falling over. (2)Shade Tolerance: Intolerant

(1)http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=L460 [11 Jan 2008] (2)http://plants.usda.gov/java/charProfile?symbol=PAVI2 [15 Jan 2008]

4.10

(1)On suitable soils, switchgrass is climatically adapted throughout the most of the United States. Moderately deep to deep, somewhat dry to poorly drained, sandy to clay loam soils are best. It does poorly on heavy soils. In the East, it performs well on shallow and droughty soil. (2)Tolerates wide range of soils, including dry ones, but prefers moist, sandy or clay soils. Tends to flop in rich soils. (3)Switchgrass grows on a wide variety of soils, but likes deep sandy loams best. It does poorly on heavy soils, although it tolerates moderate soil salinity and pH levels ranging from about 4.5 to 7.6. (3)Switchgrass grows on a variety of soils if soil moisture is adequate. Switchgrass is tolerant of moderate soil salinity and acidity, growing in soil pH ranging from 4.5 to 7.6.

(1)http://plants.usda.gov/factsheet/pdf/fs_pavi2.pdf [11 Jan 2008] (2)http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=L460 [11 Jan 2008] (3)http://www.floridata.com/ref/P/pani_vir.cfm [11 Jan 2008] (3)

4.11

(1)Switchgrass is a native, erect, coarse, warm-season perennial grass. Foliage height of mature plants is mostly between 3 and 5 feet (0.9-1.5 m),; the inflorescence, a 6- to 18-inch-long (15-46 cm) open panicle, often extends to a height of 5 to 7 feet (1.5-2.1 m).

(1)Uchytil, Ronald J. 1993. Panicum virgatum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [2008, January 15].

4.12

Possible at times. (1)Switch grass is subdominant and widely distributed in the tall-grass prairie. It generally occurs as scattered bunches. (2)The young grass blades are very palatable and a good hay for livestock. The seeds have good wildlife value, but a thick stand of switchgrass can be impenetrable for small animals. (3)Growth: RAPID GROWTH, LONG-LIVED, DENSE STAND-FORMING, TUFTED BUNCHGRASS, SOD-FORMING, DENSE FOLIAGE, CLOSE GROUND COVER, DEEP ROOTED

(1)http://www.bellmuseum.org/plants/Grasses/grass%20text/panicum%201.htm [16 Jan 2008] (2)http://www.nps.gov/heho/planyourvisit/upload/prairie%20garden%20HEHO.pdf [16 Jan 2008] (3)http://tpid.tpwd.state.tx.us/species_report.asp?species=4 [16 Jan 2008]

5.01

Terrestrial grass

5.02

Poaceae

5.03

Poaceae

5.04

(1)Propagated by Bare Root: No, Propagated by Bulb: No; Propagated by Corm No

(1)http://plants.usda.gov/java/charProfile?symbol=PAVI2 [15 Jan 2008]

6.01

Native habitat N. America, where natural reproduction is not a problem. (1)Switchgrass reproduces both sexually and vegetatively. Rhizomes are responsible for vegetative expansion, but spreading ability depends upon growth form. Some rhizomes of sod-forming ecotypes may extend to lengths of 1 to 2 feet (0.3-0.6 m), while those of bunch-forming ecotypes may extend only a few inches

(1)Uchytil, Ronald J. 1993. Panicum virgatum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [2008, January 15].

6.02

(1)Grows primarily in clumps, but may naturalize by rhizomes as well as self-seeding to form sizable colonies. Cut back clumps to the ground in late winter to early spring. May be grown from seed.

(1)http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=L460 [11 Jan 2008]

6.03

No evidence of natural hybridization. (1)Controlled hybridizations of plants are necessary for genetic studies, including those that use molecular markers. A hybridization technique for grass species such as switchgrass, Panicum virgatum L., with indurate floral bracts has not been previously reported. The objective of this study was to develop a technique for emasculating and hybridizing switchgrass. Emasculations were successful when the top of the stigmas could be seen through the translucent tips of the lemma and palea. Panicle branches containing 25 to 50 fertile florets were emasculated at this stage after removing excess panicle branches. Both sessile staminate florets and the fertile florets of a spikelet were emasculated because removal of the sessile floret damaged the upper fertile floret. Emasculations and hybridization were completed before natural pollen shed, which occurs after 1000 h in the greenhouse. Panicle branches with emasculated florets were covered with glassine bags. Anthers from florets of male parents at a similar stage of development were collected in petri dishes and shaken to induce pollen shed. Pollen in petri dishes was applied directly to stigmas of florets emasculated previously the same morning. The average percentage of crossability [(seed/floret emasculated and fertilized) 100] for crosses that produced seed was 27%, with a range of 4 to 86%. The procedure was successfully used to make controlled crosses in a greenhouse between plants of 'Summer', an upland tetraploid, and 'Kanlow', a lowland tetraploid switchgrass. (2)Abstract: Switchgrass (Panicum virgatum L.) has two cytotypes or cytoplasm types, L and U, that are associated with the lowland and upland ecotypes, respectively. The L cytotypes are tetraploids while the U cytotypes can be either tetraploids or octaploids. The objective of this research was to characterize meiotic stability of reciprocal crosses of U and L plants as indicated by chromosome pairing at meiosis and to determine the mode of inheritance of chloroplast DNA (cpDNA) in the hybrids of these cytotypes. Morphological markers that characterize the parents and hybrids also were investigated to confirm that progeny were true hybrids. Reciprocal crosses were made between Kanlow (L tetraploid) and Summer (U tetraploid) plants. Pubescence on the upper surface of the leaf blade, foliage color, and seed size were evaluated as markers to verify hybridization. Meiotic pairing of some of the hybrids was analyzed at the diakinesis stage of meiosis by means of immature anthers. The clone pRR12 from a spinach (Spinacia oleracea L.) cpDNA library was used as a chloroplast hybridization probe to determine chloroplast inheritance. For all the morphological traits evaluated, the hybrids were intermediate in comparison to the parents except for seed width. Chromosome pairing was primarily bivalent in all hybrids. The viability of the hybrid seed and the normal meiotic chromosome pairing of the hybrids indicate a high degree of similarity between upland and lowland genomes. In the cpDNA analysis, all verified hybrids examined carried a fragment identical in size to the fragment of the female parent, indicating predominance of maternal inheritance of the cpDNA in switchgrass.

(1)Martinez-Reyna, J.M. and K. P. Vogel. 1998. Controlled hybridization technique for switchgrass. Crop science 38 (3): 876-878. (2) Martinez-Reyna, J. M., K. P. Vogel, C. Caha, and D. J. Lee. 2001. Meiotic stability, chloroplast DNA polymorphisms, and morphological traits of upland X lowland switchgrass reciprocal hybrids. Crop Science 41 (5) : 1579-1583.

6.04

(1)Abstract: Switchgrass (Panicum virgatum L.), a cross-pollinated perennial, produces very little or no seed when self-pollinated, indicating the presence of self-incompatibility mechanisms. Knowledge of self-incompatibility mechanisms is required to use germplasm effectively in a breeding program. The objective of this study was to characterize features of the incompatibility systems in switchgrass. Seed set and seed characteristics of reciprocal matings of tetraploid, octaploid, and tetraploid X octaploid plants were used as measures of incompatibility. Both bagged mutual pollination and manual emasculation and pollination methods were used to make crosses. The percentages of self-compatibility in the tetraploid and octaploid parent plants were 0.35 and 1.39%, respectively. Prefertilization incompatibility in switchgrass is apparently under gametophytic control, since there were significant differences in percentage of compatible pollen as measured by percentage of total seed set between reciprocal matings within ploidy levels. Results indicated that the prefertilization incompatibility system in switchgrass is similar to the S-Z incompatibility system found in other members of the Poaceae. A postfertilization incompatibility system also exists that inhibits intermatings among octaploid and tetraploid plants. In these interploidy crosses, two very distinctive types of abnormal seed were found. When the female parent was the tetraploid plant, the resulting seed was small and shriveled, while when the female parent was the octaploid, small seed with floury endosperm was obtained. These results are similar to those obtained for endosperm incompatibility due to the endosperm balance number system found in other species. (2)Switchgrass must be cross-pollinated because it is self-incompatible.

(1) Martinez-Reyna, J. M. and K. P. Vogel. 2002. Incompatibility systems in switchgrass. Crop Science 42 (6) : 1800-1805 (2)http://www.usask.ca/agriculture/plantsci/classes/range/panicum.html [15 Jan 2008]

6.05

Wind-pollinated (1)The blooming period occurs during mid-summer. Pollination of the florets is by wind. The floret of each spikelet is replaced by a grain that is 2-3 mm. long; this grain is ovoid-oblong in shape and somewhat flattened on one side. (2)POLLINATED WITHOUT BEES, NOT HONEY PRODUCING

(1)http://www.illinoiswildflowers.info/grasses/plants/switchgrass.htm [16 Jan 2008] (2)http://tpid.tpwd.state.tx.us/species_report.asp?species=4 [16 Jan 2008]

6.06

(1)Grows primarily in clumps, but may naturalize by rhizomes as well as self-seeding to form sizable colonies.

(1)http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=L460 [11 Jan 2008]

6.07

(1)The plant's early growth will be directed into the roots, so full foliage development should not be expected until at least the third year. Seedlings bloom the first or second year. (2)Seed Age: 1 TO 4 YEARS OLD

(1)http://www.floridata.com/ref/P/pani_vir.cfm [11 Jan 2008] (2)http://tpid.tpwd.state.tx.us/species_report.asp?species=4 [16 Jan 2008]

7.01

Seeds capable of being dispersed along roads. (1)Switchgrass is one of the dominant species of the tallgrass prairie but also grows along roadsides where moisture is present. (2)Habitats include black soil prairies, clay prairies, sand prairies, typical savannas and sandy savannas, open woodlands, rocky bluffs, sand dunes, marshes and sandy pannes, rocky banks of rivers, prairie restorations, areas along railroads and roadsides, and abandoned fields. Because of its above-average tolerance of salt, this species can become the dominant grass along little-mowed roadsides where salt is applied during the winter. (3)Switchgrass (Panicum virgatum) is a native warm season perennial bunchgrass that can be found growing in Alabama along roadsides, edges of fields, and abandoned sites. It is used as a forage for grazing or hay, provides excellent erosion control, and is beneficial for wildlife such as quail. Switchgrass is well adapted to deep soils with good water-holding capacity, including well-drained to poorly-drained soils. It will tolerate flooding and will grow on sandy soils. Lowland types may grow to a height of 6 feet on moist, fertile sites.

(1)http://www.wildflower.org/plants/result.php?id_plant=pavi2 [16 Jan 2008] (2)http://www.illinoiswildflowers.info/grasses/plants/switchgrass.htm [16 Jan 2008] (3)http://efotg.nrcs.usda.gov/references/public/AL/645c.pdf [16 Jan 2008]

7.02

(1)P. virgatum is frequently grown as an ornamental. Hence it is likely to escape from cultivation and could occur at refuse dumps. The unique Belgian collection originates in the Vedre Valley but is doubtfully related with wool importation. (2)today switch grass is growing in popularity and there are now many attractive selections available from American and European sources.

(1)Verloove, F. 2001. A revision of the genus Panicum (Poaceae, Paniceae) in Belgium. Systematics and Geography of Plants 71 (1) : 53-72. (2)http://www.flower-gardening-made-easy.com/Panicum-virgatum.html [15 Jan 2008]

7.03

No evidence.

7.04

(1)Seed Dispersal Success Potential: BIRDS, MAMMALS, GRAVITY, WIND

(1)http://tpid.tpwd.state.tx.us/species_report.asp?species=4 [16 Jan 2008]

7.05

Possibly, as it grows along waterways. (1)Habitats include black soil prairies, clay prairies, sand prairies, typical savannas and sandy savannas, open woodlands, rocky bluffs, sand dunes, marshes and sandy pannes, rocky banks of rivers, prairie restorations, areas along railroads and roadsides, and abandoned fields.

(1)http://www.illinoiswildflowers.info/grasses/plants/switchgrass.htm [16 Jan 2008]

7.06

Possibly transported externally by birds. (1)Switchgrass holds up well under heavy snow and provides good fall-winter cover for rabbits and other small mammals, ducks, pheasants, and quail. The seeds are eaten by turkeys, pheasants, quail, doves, and songbirds. (2)Seed Dispersal Success Potential: BIRDS, MAMMALS, GRAVITY, WIND (3)Abstract: Dispersal of seeds by adhesion to animals, known as epizoochory, is often referred to as a significant mode of dispersal. Few studies have quantitatively examined this method of dispersal; those that do often concentrate on mammalian rather than avian dispersers. To measure the extent of this form of seed dispersal, we studied the external seed loads on the feet and feathers of four waterfowl species found in a salt marsh on the New Jersey shore. More than 75% of the birds were found to be carrying seeds, mostly on their feathers. The seeds of twelve plant species, predominantly from salt marsh plants and particularly salt grass (Distichlis spicata) and cordgrass (Spartina alterniflora), were identified in the samples. All but one species has seeds with potentially adhesive structures. Results indicate that for many salt marsh plant species, seed dispersal by adhesion to waterfowl may be a significant method of seed transport.

(1)http://www.floridata.com/ref/P/pani_vir.cfm [11 Jan 2008] (2)http://tpid.tpwd.state.tx.us/species_report.asp?species=4 [16 Jan 2008] (3)Vivian-Smith, G. and E. W. Stiles. 1994. Dispersal of salt marsh seeds on the feet and feathers of waterfowl. Wetlands 14 (4) : 316-319.

7.07

Possibly transported externally by birds, but no evidence for other animals.

7.08

(1)Seeds of switchgrass have good survival through the digestive system of cattle, reducing germination by 30%. (2)Switchgrass holds up well under heavy snow and provides good fall-winter cover for rabbits and other small mammals, ducks, pheasants, and quail. The seeds are eaten by turkeys, pheasants, quail, doves, and songbirds. (3)Fecal seeding by livestock may be an effective, low-cost means of rangeland restoration. We compared recruitment of switchgrass (Panicum virgatum L.) from seed fed to cattle and deposited in dung to that of broadcast-seeded plots receiving a comparable number of unfed seed. Although germinability of seed passed through livestock (52 to 62%) was reduced relative to that of broadcast seed (85 to 91%), recruitment of switchgrass from seed in cattle feces was equal to or superior to that of broadcast seed in terms of establishment (frequency of occurrence and density), plant growth and final plant size.

(1)http://www.usask.ca/agriculture/plantsci/classes/range/panicum.html [15 Jan 2008] (2)http://www.floridata.com/ref/P/pani_vir.cfm [11 Jan 2008] (3)Ocumpaugh, W. R., S. Archer and J.W. Stuth. 1996. Switchgrass recruitment from broadcast seed vs. seed fed to cattle. Journal of Range Management 49(4): 368-371.

8.01

(1)Fruit/Seed Abundance: High (2)Propagation: Switchgrass typically produces heavy crops of seed, but only a small percent are viable. (3)Switchgrass is capable of producing 112 kg of seeds/ha in natural areas and 330-560 kg of seeds/ha in cultivated stands.

(1)http://plants.usda.gov/java/profile?symbol=PAVI2 [11 Jan 2008] (2)http://www.floridata.com/ref/P/pani_vir.cfm [11 Jan 2008] (3)http://www.usask.ca/agriculture/plantsci/classes/range/panicum.html [15 Jan 2008]

8.02

(1)Panicles turn beige as the seeds mature in fall with the seed plumes persisting well into winter. (2)The seeds drop from the plants within a few weeks after ripening, but require dormancy at winter temperatures before they will germinate. (3)Seeds stored over 34 weeks had greater germination than seeds stored 26 weeks. Seeds buried deeply in the soil remain dormant and may persist in the seedbank until conditions are favorable for germination. Heavier seeds have greater germination and seedling emergence is greater than light seeds. Germination is also greater in coarse-textured soils compared to medium- and fine-textured soils. Seed dormancy can be reduced by pre-chilling seeds at 5 C for 2 weeks or by planting early, exposing seeds to cool, moist conditions.

(1)http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=L460 [11 Jan 2008] (2)http://www.floridata.com/ref/P/pani_vir.cfm [11 Jan 2008] (3)http://www.usask.ca/agriculture/plantsci/classes/range/panicum.html [15 Jan 2008]

8.03

Susceptible to herbicides, but sufficient information on control of this species is lacking. (1)Abstract: Recent research at Mississippi State has shown that eastern gamagrass, switchgrass, and tall fescue grown as filter strips reduce herbicide losses in runoff from cotton. Field experiments were conducted in 1997 and 1998 to evaluate the response of these perennial grasses to postemergence drift and registered rates of glyphosate and paraquat in mid-April and clethodim, fluazifop-P, glyphosate, MSMA, pyrithiobac, quizalofop-P, and sethoxydim in early June. Results indicate that filter strip implementation will not simply involve establishment and maintenance. In most instances, reductions in harvested biomass were as high or higher than visual injury assessments in mid-June. This finding suggests an inability of these perennial grasses to recover from an accidental overspray or drift, within the year of the event. Management decisions must be made to protect the filter strips from contact with herbicides used in the production system to ensure filter strip integrity and survival. (2)Switchgrass (Panicum virgatum):
PLATEAU herbicide is not recommended for the establishment of pure switchgrass stands as severe injury or death may result. PLATEAU herbicide may be applied at a rate of 2 to 4 oz per acre if switchgrass is planted in mixed stands with tolerant species, but only if some stand thinning or loss of stand can be tolerated. Mature switchgrass planting can be reclaimed from certain perennial weeds such as tall fescue, leafy spurge, johnsongrass, etc., with PLATEAU herbicide at rates of 10 to 12 oz per acre. However, severe stunting and injury is imminent. DO NOT apply PLATEAU herbicide to switchgrass if such severe injury can not be tolerated.

(1)RANKINS, A., D. R. SHAW, J. DOUGLAS. 2005. Response of Perennial Grasses Potentially Used as Filter Strips to Selected Postemergence Herbicides. Weed Technology 19(1): 73-77. (2)http://www.turffiles.ncsu.edu/pubs/weeds/plateaula.htm [16 Jan 2008]

8.04

(1)To control weeds during establishment, mow switchgrass to a height of 4 inches in May or 6 inches in June or July. Grazing is generally not recommended the first year, but a vigorous stand can be grazed late in the year if grazing periods are short with at least 30 days of rest provided between grazings. Switchgrass is the earliest maturing of the common native warm-season grasses and it is ready to graze in early summer...Switchgrass will benefit from burning of plant residues just prior to initiation of spring growth. Burning fields once every 3 to 5 years decreases weed competition, eliminates excessive residue and stimulates switch grass growth. Switchgrass used for wildlife food and cover should be burned once every 3 to 4 years to reduce mulch accumulations that inhibit movement of hatchlings and attract nest predators. (2)Switchgrass can be mowed or grazed down to about 8 in (20.3 cm) in the winter, but the stubble is important for winter insulation and should not be cut shorter than that in cold climates. This species evolved with fire and does best when burned occasionally. Switchgrass typically survives fire by regrowing from protected underground rhizomes, but the vigor of the new growth depends upon the season and intensity of the fire, and whether it is of the more fire resistant sod-forming type with rhizomes several inches below the soil surface, or the more sensitive bunchgrass type with rhizomes growing up into elevated tussocks. (3)Switchgrass is unharmed by burning because its rhizomes are resistant to the heat of the fire. Switchgrass litter is resistant to matting and provides a good fuel. Switchgrass needs periodic burning to maintain vigor and abundance. Burning stimulates tillering 32%

(1)http://plants.usda.gov/factsheet/pdf/fs_pavi2.pdf [11 Jan 2008] (2)http://www.floridata.com/ref/P/pani_vir.cfm [11 Jan 2008] (3)http://www.usask.ca/agriculture/plantsci/classes/range/panicum.html [15 Jan 2008]

8.05

Unknown