Eastern Gama Grass

Tripsacum dactyloides

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Photo of eastern gama grass flowering plant
The fingerlike seed heads of eastern gama grass have separate male and female florets. The seed-bearing, female florets are in the lower portion of each spike.
Karan A. Rawlins, University of Georgia, Bugwood.org
Other Common Name
Eastern Gamagrass
Family

Poaceae (grasses)

Description

Eastern gama grass is a native perennial bunch grass with flowering stalks up to 8 feet tall. It grows from short, stout rhizomes, and its clumps can be 4 feet wide. The leaf blades have a thickened midvein, can be about ¾ inch wide, and reach about 2 feet long. The flower heads comprise 1–4 fingerlike spikes (seed heads), each up to about 10 inches long, upright and narrowly cylindrical, that arise from the tip of the stem. The male and female flowers are separated, with the seed-bearing, female florets in the bottom half or third of each spike, and the male, pollen-bearing florets occurring in pairs at the top. The male portion of the spike often falls off as an intact unit, while each seed that forms in the female portion of the spike falls off individually. The female florets are closely appressed to the stalk and appear sunken into it. Flower heads develop May–September.

Similar species: Gama grass’s relatively close relationship to the wild ancestor of cultivated corn, or maize (Zea mays), can be seen in several characteristics they share, including the separate male and female flowers, the large size of the plant, the enlarged, white midveins in the leaves, the linear flower spikes with sessile (unstalked) florets, and the warm-season photosynthetic metabolism. Cultivated corn, however, is an annual, not a perennial, and its “cob” structure prevents it from being able to fertilize itself without human assistance. Therefore, any corn plants encountered growing outside of cultivation won’t persist.

Size

Height: flowering stems 2–8 feet

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Photo of an eastern gama grass plant showing flowering stalk, anthers, pistils, and leaves
Eastern Gama Grass Plant
Eastern gama grass is relatively closely related to cultivated corn, or maize. One shared trait is having male and female flowers separated on the plant.

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Closeup photo of eastern gama grass showing orange anthers
Eastern Gama Grass Anthers
The flowering stalks of eastern gama grass are its most diagnostic feature. This is the case with most grasses.

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Photo of the dried male section of eastern gama grass spike
Eastern Gama Grass Dried Male Spikelets
The male, pollen-bearing florets of eastern gama grass occur separately in pairs at the top of the flowering spike. The male portion of the spike often falls off as an intact unit.

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Photo of a clump of eastern gama grass with a man leaning over it and touching it
Eastern Gama Grass
. Eastern gama grass is considered highly desirable both as fodder for livestock and production of hay, and it is cultivated for these purposes.

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Photo of eastern gama grass seed stalks with prairie in background
Eastern Gama Grass in Prairie
Eastern gama grass is an important component of native upland prairies and glades.

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Closeup photo of eastern gama grass male florets shedding pollen
Eastern Gama Grass Shedding Pollen
The distinctive flower heads of eastern gama grass have all the male (pollen-producing) florets grouped at the tops of the spikes.
Habitat and conservation

Occurs in upland prairies, glades, savannas, and less commonly openings and margins of mesic to dry upland forests; also along roadsides and railroads, in fallow fields, in margins of crop fields, and in disturbed, open areas. Eastern gama grass is an important component of native upland prairies and glades. Like most other prominent tall grasses of tallgrass prairies (such as big bluestem), eastern gama grass is a warm-season grass that photosynthesizes most efficiently during the hottest part of the summer, a time when cool-season grasses may go dormant.

Distribution in Missouri

Scattered statewide, most abundant in the glaciated plains north of the Missouri River. It is found throughout much of the eastern and central United States.

Status

Within the large and diverse grass family, eastern gama grass is included in the same tribe as corn, sorghum, big bluestem, Indian grass, little bluestem, and silver grass (Miscanthus — an Asian grass popular in landscaping). The curious word “gama” apparently is derived from the word “grama,” the name used for grasses in genus Bouteloua.

Human connections

This tall, leafy grass is remarkably productive. Eastern gama grass is considered highly desirable both as fodder for livestock and production of hay, and it is cultivated for these purposes. Cattle relish it, and in many places where this grass historically grew, overgrazing by cattle caused its disappearance because repeated close cropping removes its energy stores and hampers it ability to regrow.

Some researchers have suggested that long, long ago, hybrids between gama grass and the wild ancestor of cultivated corn may have played an important role in the prehistoric origins of cultivated corn. Corn, of course, is one of the most important crop plants in the world, and continuing improvements in cultivated corn may include hybridization with gama grass and perhaps other relatives.

Ecosystem connections

Historically, elk and bison grazed on this highly nutritious grass. Because their wild herds were not fenced in and roamed freely over a vast range, they generally did not regraze any particular area before the grasses had time to recover and renew growth.

The maze of spaces between the large clumps of gama grass, covered above by the outward-arching foliage, provides valuable cover, shade, and nesting habitat for many native prairie species, including bobwhite, prairie-chickens, and other birds and small mammals.