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Grasses of the Eloise Butler Wildflower Garden

The oldest public wildflower garden in the United States

Muhly Grass

Common Name
Marsh Muhly (Muhly Grass, Green Muhly)

 

Scientific Name
Muhlenbergia racemosa (Michx.) Britton, Sterns & Poggenb.

 

Plant Family
Poaceae (Grasses)

Garden Location
Woodland

 

Prime Season
July to September flowering and seeding

 

Grass structure and definitions - PDF from Oregon State University

Ligule Types, Shapes & Margins (pdf)

 

Marsh Muhly is a native perennial grass that grows from 1 to 3.5 feet high on stiffly erect stems (culms) that are light green in color and smooth with shiny nodes, and much branched above the middle.

Leaf blades are up to 7 inches long and narrow (only 2.5 mm) , flat and dark green, rough on the surface. They are alternate and ascending.

Sheaths and Ligules: Sheaths are long and open. Ligules are truncate, membranous, and 0.6 to 1.5 mm long.

The inflorescence is a spike-like panicle up to 6 inches long but only up to 1/2 inch wide. The panicle has dense appressed branches.

Spikelets are 3 to 8 mm long, with a single floret. Glumes are subequal, 3 to 8 mm long including a short awn. Glumes are 1-veined, 1.3 to 2x the length of the lemmas, smooth surfaced or slightly rough at the tip end. The lemmas are 2.2 to 3.8 mm long, with short hairs on the lower parts and may or may not have awns but if so they are short - to 1 mm. There are 3 anthers, yellowish in color.

 

Habitat: Marsh Muhly Grass is a warm season perennial growing from rhizomes, which are long and scaly. It grows on somewhat moist sites as the common name implies, but is also found on field edges, railways and roadsides. There are about 15 Muhly grasses that grow in the Great Plains, most of which prefer drier habitats. This one prefers full sun and a moist soil. Growing by rhizomes, it is able to from dense colonies, but it does not form clumps. It is palatable for grazing animals when young but is usually not a grass considered for forage.

Names: The genus name, Muhlenbergia, is an honorary for Gotthilf Heinrich Muhlenberg (1753-1815) a U.S. citizen and German educated botanist who produced several catalogues of plants after retiring as a Lutheran pastor. The species name, racemosa, refers to the flower head being raceme - like, that is the individual flowers are stalked to a single central stem.

The author names for the plant classification are as follows: The first to classify was ‘Michx.’ which refers to Andre Michaux (1746-1802), French botanist who made many exploring expeditions in the U.S. collecting and cataloging many species. His notes were later used by his son, Francois, who with Thomas Nuttall published the multi-volume North American Sylva. His work was updated by a collaboration of 3 people - Britton, Sterns & Poggenb. ‘Britton’ is for Nathaniel Lord Britton (1859-1934) American botanist and taxonomist, co-founder of the New York Botanical Garden, Member of the Torrey Botanical Club, signatory of the American Code of Botanical Nomenclature and co-author with Addison Brown of Illustrated Flora of the Northern United States, Canada, and the British Possessions in 1896. ‘Sterns’ refers to Emerson Ellick Sterns (1846-1926) American botanist, Co-founder of the New York Botanical Garden, member of the Torry Botanical Club. ‘Poggenb.’ refers to Justus Ferdinand Poggenburg I (1840-1893), botanist. Member of the Torrey Botanical Club.

Comparisons: M. racemosa is similar to M. mexicana with which it can cross. However, M. racemosa is most similar to M. glomerata and some references group the two, however, there are distinct differences - M. glomerta has dull stem internodes with extremely short hairs and the stems are rarely branched above the base. Ligules are shorter 0.2 to 0.6 mm long whereas M. racemosa has ligules of 0.6 to 1.5 mm. A drawing comparing the details of the two Muhlenbergia species found in the Garden is shown below - M. mexicana and M. racemosa.

See bottom of page for notes on the Garden's planting history, distribution in Minnesota and North America, lore and other references.

Muhly Grass Muhly Grass Drawing

Above: The flowering raceme with maturing spikelets. Note the individually stalked spikelets. Photo ©Robert H. Molenbrock, USDA-NRCS PLANTS Database. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions.

Below: 1st photo - An example of the flowering racemes held above with the flat curving leaf blades on the upper stem. 2nd photo - A flowering head emerging from the leaf axil. Both photos ©Emmet J. Judziewicz, University of Wisconsin.

Muhly Grass plant Muhly Grass New Raceme

Below: 1st photo - A fully emerged flowering head prior to maturity. 2nd photo - Example of the leaf and stem structure. Both photos ©John Hilty, Illinois Wildflowers.

Muhly Grass Raceme Muhly Grass stems

Below: 1st photo - stem section with node. 2nd photo - Typical spikelet containing one floret. Note the length of the glumes. Both photos ©Anna Gardner, University of Iowa.

Stem section floret

Below: A drawing comparing the details of the two Muhlenbergia species found in the Garden. Drawing by Linda A. Vorobik and Annaliese Miller, ©Utah State University.

detail drawing

Notes:

Marsh Muhly Grass covers most of the United States and the lower Canadian Provinces. It is absent in most of the SE States but is most prominent in the north central states, extending west into the Rocky Mountain areas. In Minnesota it is found throughout the state in about 2/3rds of the counties with the exceptions widely scattered.

It is one of ten species of Muhlenbergia found in Minnesota. One other was reported, but never collected. Only two of those ten species, M. racemosa and M. mexicana, Mexican Muhly, are found in the Garden.

References and site links

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.

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