Fowl Mannagrass is a variable size perennial with stems (culms) being 12 to 50 inches high. Some plants will be slender and tall with open flowering heads while in other locations a plant may short and stout with relatively closed heads.
The leaf blades are flat and often folded, erect or ascending, up to 12 inches long and up to 3/16 inches wide ( 2 to 6 mm) - this would be shorter and narrower than American Mannagrass, G. grandis. The upper surface is usually a bit rough.
Sheaths & Ligules: The leaf sheath is smooth to slightly rough, keeled, and closed for most of its length. The ligule is short, up to 4mm long, and usually rounded. Both sheath and ligule are without hair.
Inflorescence: The flowering heads are panicles and are 2.5 to 8 inches long (6-25 cm), and almost as wide at the base. Branches of the panicle can be ascending at their base, but lower branches are widespread, divergent and and drooping at maturity. Branches have 15 to 50 spikelets, usually crowded in the upper 2/3 rds of the branch.
Spikelets are 1.8 to 4 mm long and 1.2 to 2.9 mm wide, flattened, oval in side view, and containing 3 to 7 florets. There are two short whitish glumes with raised veins; glumes 1.5 times longer than wide, lemmas are ovate in front view, purplish and have 7 prominent nerves. Anthers number 2, purple or yellow.
Varieties: Some authorities recognize two varieties - var. striata and var. stricta - depending on stem thickness and leaf blade width, but Minnesota authorities do not recognize these as separate plants.
Habitat: Fowl Mannagrass is found in the moist areas of shorelines, marshes, wetlands, moist wood and occasionally in shallow fresh water. It grows from a rhizome and forms tussocks.
Names: The genus name, Glyceria, is Greek for 'sweet', which is the taste of the grain, and is palatable. The species name, striata , means 'striped', referring the the prominent veins of the lemmas. The common name "mannagrass" would then be a somewhat biblical reference. The author name for the plant classification is two parted. The first to publish a classification was ‘Lam.’ which refers to Jean-Baptiste Lamarck (1744-1829) French naturalist and biologist, an early proponent of evolution who among other things, published the 3 volume Flore Francaise. He is best known for his theory of the inheritance of acquired characteristics. His work was amended by ‘Hitchc.’ which refers to Albert Spear Hitchcock (1865-1935) American botanist and agrostologist (one who studies grasses). He worked for USDA, authored more than 250 works, including the important Manual of the grasses of the United States.
Comparisons: There are two Glyceria species in the Garden - G. grandis, American Mannagrass, and G. striata. They are both plants of wet or moist areas. The two species can be easily confused with each other as both have spikelets that are short (less than 1 cm) and flattened. The key differences are in the details of the glumes and spikelet length, which is much longer in G. grandis. American Mannagrass also has leaf sheaths that are open for over half of their length, flowering heads are longer, 6 to 16 inches long (16 to 42 cm), branches spreading to drooping. One of the other more confusing species in North America will be G. elata, which exists in the western part of the range of G. striata. However, G. elata is a larger plant with larger panicles, spikelets 3 to 6 mm long instead of 1.8 to 4 mm. Without looking at specifics, the two plants look alike.
Above: Plant showing the spreading and nodding panicle branches. Photo ©Robert Soreng, USDA-NRCS Plants Database. Drawing by Cindy Roche, University of Utah.
Below: Spikelet detail, photo ©Anna Gardner, University of Iowa. Drawing courtesy of USDA-NRCS PLANTS Database / Hitchcock, A.S. (rev. A. Chase). 1950. Manual of the grasses of the United States.
Below: Spikelets in different development states: 1st photo in flower early Summer, 2nd & 3rd photos, mid-Summer, 4th photo - late Summer.
Below: 1st photo - late Summer seed grains. 2nd photo - stem sheath and ligure area.
Below: 1st photo - leaf blade upper surface. 2nd photo - leaf blade underside.
Notes: This grass is indigenous to the Garden. Eloise Butler catalogued it in her early Garden records using the nomenclature of the time - Glyceria nervata. Fowl Mannagrass is one of four species of Glyceria usually found in the state: The four are: G. borealis, Small floating mannagrass; G. canadensis, Rattlesnake mannagrass; G. grandis, American Mannagrass; and G. striata, Fowl Mannagrass.
Fowl Mannagrass is a native perennial that grows in all of Canada and in all of the United States. In is found in Minnesota throughout the state with about a dozen county exceptions, most of those in the SW Quadrant. There are about 35 species of Glyceria worldwide of which in North America there are 13 native and 3 introduced. All grow in wet areas and the native species are consumed by livestock, but are not abundant enough for major grazing use.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"