Introduction:
Creeping panic (Panicum repens) Weed.
Panicum repens is a perennial grass that frequently forms dense colonies and has long, creeping rhizomes. It grows in moist, often sandy soils and its rhizomes often extend several feet out into the water. Panicum repens frequently forms dense floating mats that impede water flow in ditches and canals and restrict recreational use of shoreline areas of lakes and ponds. Management of Panicum repens involves the repeated application of herbicides. There is very little physical management that can be used to control Panicum repens, as disturbance encourages its growth.
Description:
P. repens is a perennial grass that frequently forms dense colonies and has long, creeping rhizomes. Flowering stems are erect and up to 0.8m tall. The lower stems sometimes lack leaf blades and consist of only sheaths. Leaves of the upper stem have sheaths and blades. The blades are relatively short, flat or sometimes folded and from 2 to 5mm wide. The inflorescence is a loose, open panicle that is 3 to 10cm long that has weakly divergent to ascending branches. Spikelets are about 2.5mm long.
Geographical range:
Native range: Africa, Asia, and Europe.
Known introduced range: North America.
Distribution Map:
Creeping panic (Panicum repens) Distribution in North America shown in green.
Occurs in:
Coastland, lakes, riparian zones, water courses.
Habitat description:
P. repens grows in moist, often sandy soil along beaches and dunes, margins of lagoons, marshy shorelines of lakes and ponds, drainage ditches and canals. Its rhizomes or runners often extend several feet out into the water, and the plant frequently forms dense floating mats.
P. repens is a perennial weed that can be found along ditch banks, around ponds, along roadsides, and in managed turfgrass areas, including golf courses. This exotic grass
Close up of the Creeping panic (Panicum repens) Weed.
persists in terrestrial, wetland, and aquatic environments of tropical and subtropical regions around the world. It has spread throughout the gulf coast region from Florida to Texas. It is a serious problem in the lower coastal plain of Alabama and Mississippi, and in much of Florida where it is primarily a weed of moist, sandy soils, but it can also grow in finer textured soils.
General impacts:
The dense floating mats of P. repens may impede water flow in ditches and canals and restrict recreational use of shoreline areas of lakes and ponds.” The Florida Exotic Pest Plant Council.P. repens has been reported as a weed of 17 crops in 27 countries, and is considered one of the most serious grass weeds.” The authors go on to state that, “P. repens quickly forms monocultures that displace native vegetation, particularly in or near shallow waters.P. repens formed dense monotypic stands in response to increased hydroperiod (depth and duration of flooding).P. repens is very competitive and has reduced common bermudagrass (Cynodon dactylon (L.) Pers.) growth by nearly 40% after 2 yr. Tillage will not control P. repens, and may in fact serve to spread the weed to previously un-infested areas.Because of the lack of apical dominance, every node along the entire rhizome may sprout nearly simultaneously.
On Lake Okeechobee the ability of P. repens to disperse and become established at different water depths was evaluated in a series of experimental pond studies. These studies revealed that fragments remain buoyant for extended periods and so facilitate the dispersal of P. repens within the lake. If fragments become anchored to sediment that is either exposed or in shallow water, they can readily root and establish mature plants; Once established, P. repens can thrive in depths of 75cm or less and can survive prolonged exposure to flooding depths greater than I m. In this manner, low water periods can contribute to the dispersal and colonization pattern of P. repens in the lake. When coupled with lake elevation data, these findings suggest that low water levels or draw downs would increase the marsh area susceptible to P. repens invasion.”
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