Xyris ambigua

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Common names: coastal plain yelloweyed grass

Xyris ambigua
Xyris ambigua BM.jpg
Photo by John Bradford hosted at Bluemelon.com/poaceae
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta - Flowering plants
Class: Liliopsida - Moncots
Order: Commelinales
Family: Xyridaceae
Genus: Xyris
Species: X. ambigua
Binomial name
Xyris ambigua
Natural range of Xyris ambigua from USDA NRCS Plants Database.

Taxonomic Notes


Also known as coastal plain yelloweyed grass, X. ambigua is a native perennial forb that is a member of the Xyridaceae family.[1] The leaves are broadly linear, 15-40 cm long, curvate or slightly twisted, and its tips are either blunt or acute. Bracts range from reddish-brown to pale brown, while lateral sepals are tan to reddish with a broad, ciliate keel.[2]


X. ambigua is native to the southeast United States, ranging from eastern Texas to Virginia, mostly occupying areas along the coastline.[1]



X. ambigua can be found in communities that are not human disturbed, ranging from wet savannahs and flatwoods to pinelands and edges of depression ponds.[3] Other communities include moist sands or sandy-peats of bog margins and lakeshores.[2] As well, X. ambigua has been observed in a range of habitats including moist loamy sand in disturbed sites and savannahs, moist sandy peat in cypress domes, wet sandy peat in pine flatwoods, wet acid sands, and other bogs.[4] It increased in frequency and biomass in response to soil disturbance by clearcutting and chopping in north Florida flatwoods forests.[5]

Xyris ambigua is frequent and abundant in the North Florida Wet Flatlands community type and is an indicator species for the Lower Panhandle Savannas community type as described in Carr et al. (2010).[6]

Associated species - Scleria reticularis, Buchnera floridana, Hypericum opacum, Eryngium integrifolium, Xyris elliottii, Habenaria integra, Polygala ramosa, Polygala lutea, Ctenium aromaticum, Hibiscus aculeatus, Xyris brevifolia, Xyris caroliniana.[4]


X. ambigua has been observed to flower June through September and November.[7] Flowers close before noon when blooming.[8]

Fire ecology

X. ambigua has shown significant increase in flowering response due to the introduction of fire.[9] Populations of this species have been known to persist through repeated annual burning.[10]

Conservation, cultivation, and restoration

This species is listed as endangered in the state of Tennessee.[1]

Cultural use

Photo Gallery

References and notes

  1. 1.0 1.1 1.2 USDA Plants Database URL: https://plants.usda.gov/core/profile?symbol=XYAM
  2. 2.0 2.1 Kral, R. (1960). "The genus Xyris in Florida." Rhodora 62(743): 295-319.
  3. Weakley, A. S. (2015). Flora of the Southern and Mid-Atlantic States. Chapel Hill, NC, University of North Carolina Herbarium.
  4. 4.0 4.1 Florida State University Robert K. Godfrey Herbarium database. URL: http://herbarium.bio.fsu.edu. Last accessed: June 2018. Collectors: Loran C. Anderson, Steve L. Orzell, Edwin L. Bridges, R. Kral, R. K. Godfrey, O. Lakela, P. L. Redfeam, Robert L. Lazor, Sidney McDaniel, Wilson Baker, Ann F. Johnson, Wendy Casper, Bob Rjce, K. Craddock Burks, A. H. Curtiss, John Morrill, N. C. Henderson, Bruce Hansen, M. Davis, R. A. Norris, A. F. Clewell, Cecil R. Slaughter, T. MacClendon, K. MacClendon, and A. Gholson. States and counties: Florida: Wakulla, Nassau, Franklin, Gulf, Liberty, Martin, Leon, Citrus, Collier, Charlotte, Brevard, Jackson, Hillsborough, Orange, Bay, Walton, Okaloosa, Levy, Escambia, Santa Rosa, Holmes, Washington, Calhoun, Pasco, Jefferson, Palm Beach, Indian River, Lee, Hernando, Pinellas, Taylor, Duval, and St. Johns. Georgia: Thomas, Grady, and Coffee. Alabama: Escambia and Calhoun.
  5. Moore, W.H., B.F. Swindel, and W.S. Terry. (1982). Vegetative Response to Clearcutting and Chopping in a North Florida Flatwoods Forest. Journal of Range Management 35(2):214-218.
  6. Carr, S.C., K.M. Robertson, and R.K. Peet. 2010. A vegetation classification of fire-dependent pinelands of Florida. Castanea 75:153-189.
  7. Nelson, G. PanFlora: Plant data for the eastern United States with emphasis on the Southeastern Coastal Plains, Florida, and the Florida Panhandle. www.gilnelson.com/PanFlora/ Accessed: 29 MAY 2018
  8. Comment by Edwin Bridges on post by Rodney Felix, Walton County, May 8, 2017, posted to Florida Flora and Ecosystematics Facebook Group.
  9. Hinman, S. E. and J. S. Brewer (2007). "Responses of Two Frequently-Burned Wet Pine Savannas to an Extended Period without Fire." The Journal of the Torrey Botanical Society 134(4): 512-526.
  10. Platt, W.J., R. Carter, G. Nelson, W. Baker, S. Hermann, J. Kane, L. Anderson, M. Smith, K. Robertson. 2021. Unpublished species list of Wade Tract old-growth longleaf pine savanna, Thomasville, Georgia.