Tripsacum dactyloides, commonly called eastern gamagrass, is a warm-season, sod-forming bunch grass native to the eastern United States. Gamagrass is a distant relative of the corn species (Zea mays) and, like corn, the male part of the plant is located in the upper section of the female part. The joints of the seed-bearing part of the plant break when the plant is developed and each seed-bearing part contains one seed.
Usually gamagrass grows to a height of 2–3 feet (0.61–0.91 m), but it can be as high as 8–10 ft (2.4–3.0 m). The seed-producing season of the grass is from June to September. The seeds contain from one to numerous thorns and the size of the seed head can range from 6 to 10 inches. The distinct midrib leaves of gamagrass can grow up to a height of 12–24 inches (300–610 mm) and a width of 0.375–0.75 in (9.5–19.1 mm).
Eastern gamagrass has several short, fibrous, thick rhizomes. The deep and hollow roots of the plant branch out from lower nodes. Since the grass has short internodes, all the leaves grow out from the plant's base. Each clump's diameter can increase up to 4 ft (1.2 m).
The stems and leaves have a purplish color and are glabrous. The glabrous leaf-blade is around 1.5 m (4 ft 11 in) long, 9–35 millimetres (0.35–1.38 in) wide and has hairs at the base. The inflorescenceof the terminal axillary bud is 10–30 centimetres (3.9–11.8 in) long. The type of inflorescence is usually a single raceme or a panicle with a combination of two to three unisexual single racemes. The flowers of eastern gamagrass, which blooms from late March to early October, consist of red spikes made up of female and male spikelets. Usually spikelets of grass assist reproduction by holding the grain and fruit. When the mature female spikelets are destroyed they separate like pop-beads. Eastern gamagrass can survive droughts and floods for a long time because of its rigid and thick rhizomatous roots which firmly holding the plant upright.
Tripsacum dactyloides has different female and male flowers and is a monoecious plant. The seeds mature disproportionally and production is commonly slow. Tripsacum dactyloides is one of the species in the Poaceae family, one of the Andropogoneae tribe, and one of the sub-tribes of Tripsacinae. As the plant is a distant relative of corn, it shares common subtribes with the Zea mays corn species.
Eastern gamagrass has Tripsacum relatives throughout the United States and Mexico. The plant was first cultivated in Iowa and the southwestern United States, and the habitat range is still expanding. Tripsacum dactyloides is widely spread throughout the United States, from Connecticut to Nebraska and south to Florida and Texas. It is also found as far south as South America, in Paraguay and Brazil. Eastern gamagrass is adapted to numerous habitats like sandy soils, marshes, riverbanks, open spaces in tropical rain forests, and even rocky outcrop.
Warm season gamagrass is native to the eastern United States. The best growing conditions for eastern gamagrass are provided by wet land, such as floodplains along riverbanks. Moreover, moist, nonalkaline lowland areas will maintain the growth of gamagrass because the land can endure a longer time under flood conditions. The soil that is most suitable for eastern gamagrass is moist, little drained fertile soil that has an annual precipitation of 900–1,500 mm (35–59 in) and a pH of 5.5 to 7.5. The plant can adapt not only in moistened soil but also in drained soil due to its great tolerance for salt compared to other species. T. dactyloides can tolerate a maximum of three weeks of flooding without dying. The deep roots, which extend to around 4.5 m (15 ft) underground, are the key structure that allows gamagrass to tolerate drought.
Around the late 1980s and early 1990s, people started to pay attention to eastern gamagrass, Tripsacum dactyloides, as a good productive forage in summer, since eastern gamagrass is productive, palatable and easily digestible by almost all cattle. For these reasons, gamagrass is ideally suitable for feed crops, including hay and pasture forage for which rotation of grazing seasons is controlled. It is used as forage because the growing season of the grass is earlier compared to other warm-season grasses and later compared to cool-season grass and legumes.
Gamagrass is also suitable as a wildlife habitat. Hollow space in the middle of dispersed bundles and the tented canopy created by the leaves growing from the rhizomes and dropping into the middle make the plant an attractive location for wildlife. For example, the empty space in the middle of bundles is large enough for wild animals like quails and prairie chickens to build nests. Moreover, the grass provides good cover during the winter for grassland sparrows.
Gamagrass grows from mid-April to mid-September. This is a little earlier in the year compared to other native warm-season grasses like big bluestem, (Andropogon gerardi) and switch grass, (Panicum virgatum). The high relative yield of gamagrass in summer is the major reason why this grass is a good feedcrop when cool-season grasses ("tall fescue") are undeveloped.
Eastern gamagrass was widely considered a high class feedcrop among the early settlers of the United States. However, it started to disappear because of grain crops and cattle grazing. Native animals like buffalo and elk grazed in areas where eastern gamagrass grew before European settlement and then moved to other areas until fresh grass grew to replace the grazed places. Eastern gamagrass requires a moderate amount of carbohydrates stored in the leaf bases for regrowth. If the plant is grazed before carbohydrate accumulates in the leaf bases the plant will die from overgrazing.
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