The federal plant materials center in Big Flats, New York has been growing northern gamma grass since the 1980s, when they began genetic experiments to improve the quality of the plants for cattle forage, site restoration, and biomass production (Salon and Dewald 2000). Plants found west of the coastal plain are not considered native to New York, because of this production and distribution.
There are 11 existing populations but only two of them have hundreds of plants. Most occurrences are very small in area. One occurrence from 1988 was extirpated by Phragmites. There are 10 other historical occurrences.
Populations seem stable, but not enough work has been done to resurvey current populations to add to trend information.
The number of populations has probably remained about the same over time, although historical populations were probably larger in size because they were less constricted by development.
Exotic invasive species are the main threats to this grass, especially common reed (Phragmites australis) invading salt marsh habitats.
This species needs disturbance to reduce competition from woody plants or more aggressive herbaceous plants, but too much direct disturbance to the plants will reduce or eliminate the population. Its habitat could be disturbed in the non-growing season to open it up for seed germination and colonization, but direct disturbance should be prevented during the growing season.
Genetic studies could be done to distinguish populations that have been introduced for livestock or erosion control from native populations.
In New York, Tripsacum dactyloides has been collected in a variety of habitats near the coast, including high salt marsh, wet meadows, oak forests, old fields, roadsides, and dunes (New York Natural Heritage Program 2010). Water courses and limestone outcrops (FNA 2003). Swamps and wet soil (Gleason and Cronquist 1991).
This grass is native from Orange County south through New York City to Eastern Long Island. It is now considered extirpated in Brooklyn. It is also distributed by the Natural Resources Conservation Service in Central and Western New York for planting as cattle forage. It has also turned up in seed mixes for restoration projects.
This grass grows in the Atlantic Coast States from Massachusetts south through Florida. It extends west from the Virginias to Southeastern Nebraska and Eastern Kansas south through Texas.
Northern Gamma Grass has clumped stems from 1 to 2 meters tall. The leaf blades are 30 to 75 cm long, 9 to 35 mm wide, and flat. The infloresence is terminal, with normally 2 to 3 erect branches, each 12 to 25 cm long. The pistillate spikelets are 6 to 8 mm long and 3 to 4.4 mm wide, below and more tightly compacted into the same raceme as the staminate spikelets (FNA 2003).
Northern Gmma Grass is most easily identified in flower or fruit, though vegetative individuals may also be identified.
Tripsacum dactyloides is the only member of the genus in New York. Its wide leaves and terminal infloresence with long (12-25 cm) branches are distinctive.
Eastern Gamma Grass flowers in July and August and the fruiting plants persist into November.
The time of year you would expect to find Northern Gama Grass flowering and fruiting in New York.
Northern Gama Grass
Tripsacum dactyloides (L.) L.
Flora of North America Editorial Committee. 2003. Flora of North America, North of Mexico. Volume 25. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford University Press, New York. 783 pp.
Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.
Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.
Hitchcock, A.S. 1951. Manual of the grasses of the United States. 2nd edition revised by Agnes Chase. [Reprinted, 1971, in 2 vols., by Dover Publications, Incorporated, New York.]
Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.
New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.
New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.
Rhoads, Ann F. and Timothy A. Block. 2000. The Plants of Pennsylvania, an Illustrated Manual. University of Pennsylvania Press, Philadelphia, PA.
Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://www.nyflora.org/, Albany, New York
Information for this guide was last updated on: February 28, 2011
Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Tripsacum dactyloides. Available from: https://guides.nynhp.org/northern-gama-grass/. Accessed January 17, 2019.