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A3597 Pascopyrum smithii Wet Meadow Alliance

Type Concept Sentence: This herbaceous alliance is found in the southern Great Plains from Nebraska to Oklahoma and northern Texas in depressions or along streams and Pascopyrum smithii is dominant.

Common (Translated Scientific) Name: Western Wheatgrass Wet Meadow Alliance

Colloquial Name: Western Wheatgrass Wet Meadow

Hierarchy Level:  Alliance

Type Concept: This herbaceous alliance is found in the southern Great Plains from Nebraska to Oklahoma and northern Texas. Overall, grasses, and especially mid grasses, dominate stands of this alliance. Forbs can be abundant or even dominant in some stands, and short grasses become more abundant under grazing pressure. Pascopyrum smithii is the typical dominant species and can be strongly dominant, sometimes with Panicum virgatum as a codominant. Associated species vary with amount of flooding and grazing. Agrostis hyemalis, Eleocharis macrostachya, Eleocharis palustris, Elymus virginicus, and Hordeum jubatum are often present. Bouteloua dactyloides can be common on grazed sites. Stands occur in depressions or along streams. These sites retain water from snowmelt and rains and may flood for short periods but dry out for most of the growing season, and this type may overlap with moist mixedgrass prairie types.

Diagnostic Characteristics: This alliance is characterized by stands dominated by Pascopyrum smithii over a claypan. Sites are usually flooded for some time in the spring but dry out for most of the growing season.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: The dominant species Pascopyrum smithii can be abundant in upland or other intermittently flooded alliances as well as this alliance. Differential species need to be better documented, though the environmental setting (ephemeral wetlands) is a good diagnostic feature. This alliance may not fit the group concept as well as others. Possibly these are southern Great Plains mixedgrass prairie associations.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This is an herbaceous alliance, with most stands dominated by mid grasses. Stands that have more grazing pressure or are drier than average tend to have higher amounts of short grasses. Stands in the southern part of this alliance''s range that have longer than normal flooding can have abundant annual forbs occur on bare patches. The vegetation ranges in height and density with available moisture; sites that have consistent moisture availability have denser and taller vegetation, up to approximately 1 m tall.

Floristics: Pascopyrum smithii is the typical dominant species and can be strongly dominant, sometimes with Panicum virgatum as a codominant. Associated species vary with amount of flooding and grazing. Agrostis hyemalis, Eleocharis macrostachya, Eleocharis palustris, Elymus virginicus, and Hordeum jubatum are often present. Bouteloua dactyloides (= Buchloe dactyloides) can be common on grazed sites. Early-season ephemeral annuals such as Alopecurus carolinianus, Elatine rubella, Myosurus minimus, and Veronica peregrina are ubiquitous, and Limosella aquatica and Plagiobothrys scouleri may be common. Perennial forbs are conspicuous in some places, including Ambrosia spp., Oenothera canescens, Phyla cuneifolia (= Lippia cuneifolia), and Vernonia fasciculata. Stands of this alliance often occur at the margin of playa and pond marsh communities and grade into upland tallgrass and mixedgrass prairie. The extent and species composition of stands vary with water levels from year to year. Species diversity is low to moderate.

Dynamics:  Stands in this alliance are found in low parts of the local landscape and receive runoff from surrounding areas. This creates more mesic conditions on these stands than is typical of surrounding uplands. This alliance does not flood for extended parts of the growing season, though nearby, deeper parts of a depression may contain wetland vegetation.
Environmental Description:  Stands occur in depressions or along streams. These sites retain water from snowmelt and rains and may flood for short periods but dry out for most of the growing season. Surface soils are fine-textured loam, silt, or clay and are typically formed from loess or alluvium. A subsurface layer of impermeable soil prevents water from infiltrating quickly. After snowmelt or heavy rains, stands retain much of the water in the upper soils for some time and may flood or become saturated. Stands in this alliance are not flooded for extended portions of the growing season, though they may go through more than one cycle of becoming wet and dry in a single year.
Geographic Range: This alliance is found in the Great Plains from Nebraska to northern Texas and Oklahoma.

Nations: US

States/Provinces:  CO, KS, NE, OK, TX


Confidence Level: Low

Confidence Level Comments: No Data Available
Grank: GNR

Greasons: No Data Available
Type Name Database Code Classification Code
Class 2 Shrub & Herb Vegetation Class C02 2
Subclass 2.C Shrub & Herb Wetland Subclass S44 2.C
Formation 2.C.4 Temperate to Polar Freshwater Marsh, Wet Meadow & Shrubland Formation F013 2.C.4
Division 2.C.4.Nd Eastern North American Temperate Freshwater Marsh, Wet Meadow & Shrubland Division D323 2.C.4.Nd
Macrogroup 2.C.4.Nd.5 Prairie Cordgrass - Cattail species - Bulrush species Great Plains Marsh, Wet Meadow, Shrubland & Playa Macrogroup M071 2.C.4.Nd.5
Group 2.C.4.Nd.5.e Western Wheatgrass - Vine-mesquite - Buffalograss Playa & Rainwater Basin Wetland Group G136 2.C.4.Nd.5.e
Alliance A3597 Western Wheatgrass Wet Meadow Alliance A3597 2.C.4.Nd.5.e
Association CEGL002038 Western Wheatgrass - Buffalograss - (Wedgeleaf, Spotted Evening-primrose) Wet Meadow CEGL002038 2.C.4.Nd.5.e
Association CEGL005019 Switchgrass - Western Wheatgrass Southern Wet Meadow CEGL005019 2.C.4.Nd.5.e
Concept Lineage: This alliance contains two associations; one each from A.1354and A.1328.

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: >< Elytrigia smithii Series (Johnston 1987)
? Pascopyrum smithii herbaceous alliance (Hoagland 1998a)
Concept Author(s): J. Drake, in Faber-Langendoen et al. (2013)

Author of Description: S. Menard and D. Faber-Langendoen

Acknowledgements: No Data Available

Version Date: 04-28-14
  • Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
  • Hoagland, B. W. 1998a. Classification of Oklahoma vegetation types. Working draft. University of Oklahoma, Oklahoma Natural Heritage Inventory, Norman. 43 pp.
  • Johnston, B. C. 1987. Plant associations of Region Two: Potential plant communities of Wyoming, South Dakota, Nebraska, Colorado, and Kansas. R2-ECOL-87-2. USDA Forest Service, Rocky Mountain Region. Lakewood, CO. 429 pp.
  • Weaver, J. E., and F. W. Albertson. 1956. Grasslands of the Great Plains: Their nature and use. Johnsen Publishing Co., Lincoln, NE. 395 pp.