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Xyris tennesseensis

Kral

Tennessee Yellow-eyed-grass

G2Imperiled Found in 6 roadless areas NatureServe Explorer →
G2ImperiledGlobal Rank
Very highThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.148370
Element CodePMXYR010M0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderCommelinales
FamilyXyridaceae
GenusXyris
Other Common Names
Tennessee yelloweyed grass (EN)
Concept Reference
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2023-11-07
Change Date2000-02-27
Edition Date2023-11-07
Edition AuthorsBishop, A. (2006), rev. C. Nordman (2023).
Threat ImpactVery high
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences6 - 80
Rank Reasons
Tennessee Yellow-eyed-grass (Xyris tennesseensis) occurs in the southeastern United States, almost exclusively within the Ridge and Valley and the Interior Low Plateau, and only in highly localized areas of Middle Tennessee, Alabama, and northwest Georgia. Despite extensive surveys, fewer than 30 populations are known to be extant. Sites (or occurrences) generally occupy less than half a hectare. About eight occurrences have been extirpated in recent decades. It is threatened by habitat alteration for development, timber production and management, gravel quarrying, highway maintenance and construction and woody plant encroachment and invasive plant encroachment.
Range Extent Comments
Tennessee Yellow-eyed-grass (Xyris tennesseensis) occurs in the southeastern United States, almost exclusively within the Ridge and Valley and the Interior Low Plateau, and only in highly localized areas of Middle Tennessee, Alabama, and northwest Georgia. Range extent was estimated to be 43,000 square kilometers, using herbarium specimens, NatureServe Network occurrence data, and data from the U.S. Fish and Wildlife Service, collected between 2002 and 2023 (NatureServe 2023, SEINet 2023, USFWS 2021).
Occurrences Comments
Based on NatureServe Network occurrence data, herbarium records, and data from the U.S. Fish and Wildlife Service, documented between 2002 and 2023, there are about 28 occurrences of Tennessee Yellow-eyed-grass rangewide, including 14 in Alabama, 8 in Georgia, and 6 in Tennessee. Using another method, the U.S. Fish and Wildlife Service, in 2021 determined there were 21 extant populations, composed of 26 sites (NatureServe 2023, SEINet 2023, USFWS 2021).
Threat Impact Comments
Xyris tennesseensis is a very rare wetland plant species with less than 30 known populations. These populations are threatened by habitat alteration for development, timber production and management, gravel quarrying, highway maintenance and construction and woody plant encroachment and invasive plant encroachment. Clear-cutting has occurred on the upper slopes of sites that could lead to soil erosion and water quality degradation. Alteration of wetlands and hydrology which would cause the substrate to dry out would be detrimental to the species. In Georgia, a site was destroyed by highway construction, and in Alabama, a roadside site has declined due to herbicide spraying and other maintenance. Because the seeds require open, wet habitat to germinate, major threats to survival are competition and encroachment of woody plant species and invasive exotic plants, especially Nepal grass (Microstegium vimineum), marsh dayflower (Murdannia keisak), and hairy jointgrass (Arthraxon hispidus). Extreme drought is a threat, such as may be associated with climate change (Kral 1990, USFWS 1991, USFWS 2021, Pyne et al. 1995).
Ecology & Habitat

Description

A perennial herb with basal, mostly erect, slightly twisted linear leaves, and rounded unbranched flowering stems, arising from a bulbous base. Leaves 1-4.5 dm long, 1 cm wide, flowering stems mostly 3-7 dm tall. The overlapping leaf blades are reddish-purple. Inflorescence consists of brown, compact cone-like spikes, which occur singly at the tips of the flowering stems and contain small, pale yellow flowers, subtended by spirally arranged woody scales which hide the bud and fruit. The flowers open in late morning and close by mid-afternoon with only 1 or 2 flowers evident at any one time. Flowering occurs from August through September. The minuscule seeds are farinose and are dispersed in the fall (Somers 1994).

Diagnostic Characteristics

Leaves are twisted and without strongly raised nerves, base bulbous and reddish-purple. The small flowers open in late morning and close by mid-afternoon. The lateral sepals are narrow and the upper part lacerate. Two other Xyris species that could occur in the same habitat as X. tennesseensis are X. jupicai and X. torta. X. jupicai has a greenish non-bulbous base, leaves not twisted and a flattened flowering stem. X. torta has twisted strongly ribbed leaves (Kral 1990, Pyne et al. 1995).

Habitat

Although Xyris species are usually found on acidic soils, X. tennesseensis is unusual, it is restricted to basic or circumneutral soils that thinly cover calcareous substrates with year-round seepage or mineral-rich water flow. This species is found in open or thin canopy woods in gravelly seep-slopes or gravelly bars and banks of small streams, springs and ditches, its associates are fen or basic soil plants, it has been found at elevations up to 250 meters (Flora of North America Editorial Committee 2000, Kral 1990).

Ecology

Tennessee yellow-eyed grass is also vulnerable to localized extinction due to the small number of occurrences and small sizes of extant populations within the limited range. It has low levels of genetic diversity and experiences virtually no gene flow among populations within those regions (Downey and Baskauf 2020). "Flower production and (perhaps) seedling recruitment are most extensive in locations that are relatively sunny and lack an overstory of shrub or tree canopies", management to reduce shading by woody plants may be needed for various sites (USFWS 2021).
Terrestrial Habitats
Grassland/herbaceous
Palustrine Habitats
HERBACEOUS WETLANDFORESTED WETLANDBog/fenRiparian
Other Nations (1)
United StatesN2
ProvinceRankNative
GeorgiaS1Yes
AlabamaS1Yes
TennesseeS1Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentSmall (1-10%)Serious or 31-70% pop. declineHigh (continuing)
3 - Energy production & miningRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
3.2 - Mining & quarryingRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
4 - Transportation & service corridorsRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
4.1 - Roads & railroadsRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
5 - Biological resource useRestricted (11-30%)Moderate or 11-30% pop. declineHigh - moderate
5.3 - Logging & wood harvestingRestricted (11-30%)Moderate or 11-30% pop. declineHigh - moderate
8 - Invasive & other problematic species, genes & diseasesLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
11 - Climate change & severe weatherLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)
11.2 - DroughtsLarge (31-70%)Serious or 31-70% pop. declineHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (6)
Alabama (3)
AreaForestAcres
Blue MountainTalladega National Forest4,986
Cheaha ATalladega National Forest236
Oakey MountainTalladega National Forest6,129
Georgia (3)
AreaForestAcres
Foster BranchChattahoochee National Forest171
Ken MountainChattahoochee National Forest527
Pink KnobChattahoochee National Forest12,127
References (15)
  1. Downey, K.M., and C.J. Baskauf. 2020. Population genetics of a rare wetland species, the Tennessee yellow-eyed grass (<i>Xyris tennesseensis</i>, Xyridaceae). Conservation Genetics 21(4): 735–746.
  2. Flora of North America Editorial Committee (FNA). 2000. Flora of North America north of Mexico. Vol. 22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Oxford Univ. Press, New York. xxiii + 352 pp.
  3. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
  4. Kral, R. 1978. A new species of Xyris (sect. Xyris) from Tennessee and northwestern Georgia. Rhodora 80(823): 444-447.
  5. Kral, R. 1983c. A report on some rare, threatened, or endangered forest-related vascular plants of the South. U.S. Dept. of Agriculture Forest Service Technical Publication R8-TP2, Athens, GA. 1305 pp.
  6. Kral, R. 1990. Status report on <i>Xyris tennesseensis</i>. Unpublished manuscript submitted to USFWS, Jackson, MS.
  7. NatureServe. 2023. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  8. Norquist, C. 1991. Endangered and threatened wildlife and plants; proposed endangered status for the plant Xyris tennesseensis (Tennessee yellow-eyed grass). Fed. Register 56(32):6341-6345.
  9. Pyne, M., M. Gay, and A. Shea. 1995. Guide to rare plants - Tennessee Division of Forestry District 6. Tennessee Dept. Agriculture, Division of Forestry, Nashville.
  10. Somers, P. 1994. Tennessee yellow-eyed grass (Xyris tennesseensis Kral) recovery plan. Prepared for the U.S. Fish and Wildlife Service, Atlanta, Georgia.
  11. Southwest Environmental Information Network (SEINet). 2023. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2023).
  12. Tennessee Department of Environment and Conservation (TDEC). 2000. Demographic monitoring of Tennessee yellow-eyed grass (<i>Xyris tennesseensis</i> Kral). Unpublished report for U.S. Fish and Wildlife Service, Southeast Region, Asheville NC.
  13. Tennessee Department of Environment and Conservation (TDEC). 2001. Demographic monitoring of Tennessee yellow-eyed grass (<i>Xyris tennesseensis</i> Kral). Unpublished report for U.S. Fish and Wildlife Service, Southeast Region, Asheville NC.
  14. U.S. Fish and Wildlife Service (USFWS). 1991. Endangered status for the plant <i>Xyris tennesseensis</i> (Tennessee yellow-eyed grass). Federal Register 56(144): 34151-34154.
  15. U.S. Fish and Wildlife Service (USFWS). 2021. Tennessee yellow-eyed grass (<i>Xyris tennesseensis</i>) 5-Year Review: Summary and Evaluation. U.S. Fish and Wildlife Service, South Atlantic-Gulf Region, Alabama Ecological Services Field Office. Daphne, Alabama. Online. Available: https://fws.gov/node/5099396 https://ecosphere-documents-production-public.s3.amazonaws.com/sams/public_docs/species_nonpublish/3303.pdf (accessed 2023).