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Species
Panicum repens L.
IUCN
NCBI
EOL Text
United States
Origin: Exotic
Regularity: Regularly occurring
Currently: Unknown/Undetermined
Confidence: Confident
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | NatureServe |
Source | http://explorer.natureserve.org/servlet/NatureServe?searchName=Panicum+repens |
"Perennials. Culms 30-75 cm long, erect or trailing, rhizomatous, rooting at the lower nodes; nodes glabrous. Leaves 7-24 x 0.4-0.7 cm, linear or linear-lanceolate, base shallowly cordate, apex acuminate, distichous, glaucous, scattered-pubescent on the upper surface; sheaths to 7 cm long, ciliate along the margins; ligules membranous, with dense tuft of hairs behind. Panicles 6-18 cm long. Spikelets 2.5-3.5 mm long, oblong-lanceolate, acute; pedicels 2-5 mm long. Lower glume c. 1 x 1.5 mm, ovate. Upper glume 2-3 x 1-1.5 mm, ovate-lanceolate, acute. Lower floret male. Upper floret bisexual. First lemma 2-3 x 1-1.5 mm, ovate-lanceolate. Palea c. 2.5 x 1 mm, oblong-lanceolate, hyaline, 2-keeled. Stamens 3. Second lemma 1.5-2. x 0.5-1 mm, oblong, subcoriaceous. Palea elliptic, subcoriaceous. Stamens 3. Ovary ovate; stigma c. 1 mm long."
More info for the term: fuel
The limited information available (2011) suggests that torpedograss populations develop heavy fuel loads that may alter fire characteristics.
In Florida, torpedograss grows in dense stands and may comprise 80% of the biomass of an area where it establishes (personal communication [6]). Along the shores of Lake Kariba, Zimbabwe, the average standing crop biomass of torpedograss was 7,620 ± 21.8 kg/ha with an average moisture content of 72.91% ± 0.24 (sampled February to May) [16]. Dead leaves and culms of torpedograss accumulate in areas without grazing [79].
One manager from Florida believes that populations of torpedograss accumulate much more fuel than the native plant communities that it replaces, particularly in sawgrass (Cladium jamaicense) and spikerush prairies and American white waterlily sloughs. The increased biomass may lead to "hotter" fires resulting in higher mortality of native species, particularly sawgrass (personal communication [6]).
Corrientes de agua
Panicum repens se encuentra frecuentemente en ríos, humedales y hábitats marginales. Tolera varios días en agua estancada y sequías puede encontrarse en suelos pesados de tierras altas (Sayer &Lavieren 1975, Langeland &Burks 1998). Esta especie está adaptada a zonas con una precipitación estacional considerable y no sobrevive estaciones calurosas y secas extensas.
Salinidad
Panicum repens exhibe una tolerancia limitada a la salinidad. Ha sido registrada en arenas salinas en el oeste de Zambia (Smithsonian Marine Station at fort Pierce, 2011).
Temperatura
La distribución del zacate está restringida a las regiones tropicales y sub-tropicales, ya que la parte superior de la planta es muy vulnerable a las heladas (Smithsonian Marine Station at Fort Pierce, 2011).
License | http://creativecommons.org/licenses/by-nc-sa/2.5/ |
Rights holder/Author | CONABIO |
Source | No source database. |
More info for the term: nonnative species
Torpedograss has been widely planted as forage for livestock and may have some nutritional value to wildlife.
Palatability and nutritional value: Torpedograss has been planted throughout the world as forage for domestic livestock [2,44,65,69,79]. A nonnative species guide reports that, though used for pasturage, torpedograss has relatively low nutritional value, protein content, and palatability compared to other grasses. Its advantage as a forage grass is that it is relatively palatable when young and can withstand heavy grazing and trampling [49]. It can be fed to cattle either green or as hay [31]. However, torpedograss was reported as poisonous to horses in Florida [92,109].
Torpedograss may have some value as food for wildlife. Populations of torpedograss near Lake Okeechobee supported a diverse arthropod and nematode fauna, and plants were not limited by invertebrate herbivory or damage [29]. In feeding trials in Florida, it was consumed by the nonnative channeled apple snail (Pomacea insularum) [4,5]. On the Mississippi River delta, both above- and belowground vegetation of torpedograss was eaten by snow geese and brants in the fall [72]. It was eaten by redbread tilapia (Tilapia rendalli) in Lake Kariba in Zimbabwe [16]. Seeds of torpedograss were found in fecal pellets of wild spur-thighed tortoises in Spain [26].
Cover value: No information is available on this topic.
torpedograss
couch panicum
dog-tooth grass
torpedo grass
"
Global Distribution
Tropics and subtropics of both hemispheres
Indian distribution
State - Kerala, District/s: All Districts
"
Several Panicum congeners similar in appearance occur in Florida. Beachgrass (Panicum amarum), redtop panicum (P. rigidulum), and maidencane (P. hemitomon) all can be found within the IRL watershed counties). Details of the rhizomes, leaves, and inflorescence must be studied to distinguish among species.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | Text can be freely copied and altered, as long as original author and source are properly acknowledged. |
Source | http://www.sms.si.edu/irlspec/Panicum_repens.htm |
More info for the terms: cover, fire management, high-severity fire, peat, prescribed fire, rhizome, top-kill, wildfire
Fire adaptations: Torpedograss exhibits some characteristics that enable it to survive fire. It is rhizomatous (see Vegetative regeneration), and managers report that rhizomes below the soil surface generally survive fire ([7], personal communication [6]). Torpedograss also often establishes in moist to wet areas where rhizomes are generally protected from fire damage, though aerial portions may burn [7]. Torpedograss has been observed sprouting following fire [45,46,92,98] (see Plant response to fire, below), herbicide application [14,39,54,59,83,92], grazing [79], cutting, [19,39], and plowing or disking [83,92]. However, rhizomes show some sensitivity to heat, so high-severity fire may kill rhizomes [7]. Growth chamber experiments showed that rhizomes died after 1 hour of immersion in heated water (>140 °F (60 °C)) [109].
As of this writing (2011), the limited available information suggests that torpedograss is not particularly adapted to establishing in burned areas via dispersed seeds or from the soil seed bank (see Seed production, Seed banking, and Germination).
Plant response to fire: The available information suggests that torpedograss biomass is reduced following fire but plants often survive and sprout quickly. Mortality may occur in areas where local conditions (e.g., moisture, soil depth) expose rhizomes to heat. Postfire recovery is likely, though recovery may be limited in areas that experience flooding or are treated with herbicides.
Several sources report torpedograss surviving and sprouting soon after fire in Florida. One manager in Florida observed that torpedograss exhibits faster postfire recovery than native plants, allowing it to dominate burned areas at the expense of native vegetation (personal communication [6]). Managers report that in areas around Lake Okeechobee where water depth was approximately 2 to 3 inches (5-8 cm), torpedograss recovered "rapidly and vigorously" following initial biomass reduction after fire, with new growth sprouting from previously dormant buds [7]. After a May prescribed fire near East Lake Tohopekaliga, Florida, torpedograss sprouted "immediately" in areas that were burned or burned and disked. Rhizome biomass was reduced by 66% in burned areas and 93% in burned and disked areas 100 days after treatment but recovered to approximately 20% of pretreatment levels after 250 days in both treatments [92]. Two studies provide information on aboveground growth after wildfire in the Lake Okeechobee region. One month after an August wildfire, the average torpedograss height in burned areas was 4 to 8 inches (10-20 cm) compared to ≥30 inches (70 cm) in unburned areas [45]. Six weeks after top-kill from a February wildfire, torpedograss height averaged 8 inches (20 cm) [46].
In Florida, managers observed torpedograss mortality in areas exposed to unusual drought conditions, where water levels receded 2 to 3 feet (0.6-0.9 m) below the surface of the ground. Fire consumed both aboveground vegetation and the upper, dry, compacted peat layers to a depth of 3 to 4 inches (8-10 cm). Torpedograss mortality was also observed following a prescribed fire in 1990 and a wildfire in 1997; in both years, water levels were below the ground's surface [7]. However, dry conditions do not always result in torpedograss mortality. In 2007, torpedograss populations in marshes around Lake Okeechobee survived repeated fires during a record low-water period (personal communication [6]).
Flooding after fire may also lead to torpedograss mortality. One manager from Florida reported that he expected torpedograss populations to respond well and potentially expand following fire, depending on postfire water levels; he observed torpedograss mortality and a subsequent population decline in an area that experienced flooding for months following fire (personal communication [6]). In the Florida Everglades, torpedograss cover was significantly lower 1 year after a mixed-severity prescribed fire in areas flooded after treatment (P<0.001) [98]. See Fire Management Considerations for more information on this study.
Herbicide treatment following fire may reduce torpedograss populations. See Fire Management Considerations for more information.
Long-term impacts of fire on torpedograss have not been reported as of this writing (2011).
A nonnative plant guide suggests that torpedograss flowers nearly year round [65]. Flowering months range from May to November in Florida [25,43,113,114,115]. Herbarium records from Texas documented it flowering and fruiting in June, July, August, October, and December [36].
Torpedograss growth may be related to local hydroperiods. In Sierra Leone, torpedograss rhizomes were dormant while under seasonal floodwater from mid-June to early January. As floodwaters retreated, shoots grew to a height of 3 feet (1 m) in 3 months. Seeds were produced in June [27].