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A4094 Sporobolus clandestinus - Clinopodium arkansanum - Delphinium carolinianum Nepheline Syenite Bedrock Grassland Alliance

Type Concept Sentence: This distinctive vegetation represents glades and barrens found on nepheline syenite, a distinctive igneous rock present in the West Gulf Coastal Plain (and Ouachitas), restricted to the state of Arkansas.

Common (Translated Scientific) Name: Rough Dropseed - Limestone Calamint - Carolina Larkspur Nepheline Syenite Bedrock Grassland Alliance

Colloquial Name: West Gulf Coastal Plain Nepheline Syenite Barrens & Glade

Hierarchy Level:  Alliance

Type Concept: This distinctive vegetation represents glades and barrens found on nepheline syenite, a distinctive igneous rock present in the West Gulf Coastal Plain (and Ouachitas), restricted to the state of Arkansas. Some examples will have open stands of Quercus stellata, but trees may be absent. Some typical dominant grasses include Aristida purpurascens, Piptochaetium avenaceum, Schizachyrium scoparium, and Sporobolus clandestinus. Other herbs may include Camassia scilloides, Clinopodium arkansanum, Delphinium carolinianum, Sabatia campestris, and Phemeranthus calycinus. Lichens are common on the rocky substrate of some examples. Plant species that are common to both associations of this alliance include the forbs Agalinis skinneriana, Allium cernuum, Chrysopsis pilosa, Coreopsis lanceolata, Digitaria cognata, Glandularia canadensis, Stenaria nigricans, Houstonia longifolia, Hypericum gentianoides, Hypericum punctatum, Hypoxis hirsuta, Krigia virginica, Liatris squarrosa var. hirsuta, Liatris squarrulosa, Manfreda virginica, Monarda fistulosa, Opuntia humifusa, Schizachyrium scoparium, Scleria ciliata, Sideroxylon lanuginosum, Yucca arkansana, and the woody plants Diospyros virginiana, Rhus copallinum and Ulmus alata. Zonal vegetation communities are present around the outcrops. Interior herbaceous-dominated zones can be mesic to wet as springs and small ephemeral streams flow across the rock outcrops and water may pool in flat areas. Deeper, more heavily wooded vegetation develops along the flat or slightly sloping outcrop edges.

Diagnostic Characteristics: Examples of this alliance are restricted to nepheline syenite outcrops of the Upper West Gulf Coastal Plain of Arkansas. There are also nepheline syenite outcrops in the adjacent Ouachitas, but these are not known to have extant glade communities. They have a distinctive herbaceous flora and very low cover of trees.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: No Data Available

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: These glades and barrens areas present only in Saline and Pulaski counties, Arkansas, on distinctive, massive outcrops of igneous substrate ("nepheline syenite"). They have a distinctive herbaceous flora and very low cover of trees. Zonal vegetation communities are present around the outcrops. Interior herbaceous-dominated zones can be mesic to wet as springs and small ephemeral streams flow across the rock outcrops and water may pool in flat areas. Deeper, more heavily wooded vegetation develops along the flat or slightly sloping outcrop edges.

Floristics: Some examples will have open stands of Quercus stellata, but trees may be absent. Some typical dominant grasses include Aristida purpurascens, Piptochaetium avenaceum, Schizachyrium scoparium, and Sporobolus clandestinus. Other herbs may include Camassia scilloides, Clinopodium arkansanum, Delphinium carolinianum, Sabatia campestris, and Phemeranthus calycinus (= Talinum calycinum). Lichens are common on the rocky substrate of some examples. Plant species that are common to both associations of this alliance include the forbs Agalinis skinneriana, Allium cernuum, Chrysopsis pilosa (= Heterotheca pilosa), Coreopsis lanceolata, Digitaria cognata, Glandularia canadensis, Stenaria nigricans (= Hedyotis nigricans), Houstonia longifolia, Hypericum gentianoides, Hypericum punctatum, Hypoxis hirsuta, Krigia virginica, Liatris squarrosa var. hirsuta, Liatris squarrulosa, Manfreda virginica, Monarda fistulosa, Opuntia humifusa, Schizachyrium scoparium, Scleria ciliata, Sideroxylon lanuginosum, Yucca arkansana, and the woody plants Diospyros virginiana, Rhus copallinum and Ulmus alata.

Dynamics:  Interior herbaceous-dominated zones can be mesic to wet as springs and small ephemeral streams flow across the rock outcrops and water may pool in flat areas. Deeper, more heavily wooded vegetation develops along the flat or slightly sloping outcrop edges.
Environmental Description:  Nepheline syenite is a medium- to coarse-grained, light- to medium-gray, igneous rock that is composed predominantly of a silicate mineral called orthoclase (KAlSi3O8) and has a granite-like appearance. It may be distinguished from granite by little or no quartz content (free SiO2). In Arkansas, nepheline syenite has been intruded into the sequence of Paleozoic sedimentary rocks. Locally, quarrymen recognize "blue granite" and "gray granite" varieties. Nepheline syenite and its associated igneous rocks are exposed in four areas of the state: south-central Pulaski County between Little Rock and Sweet Home, Saline County in the vicinity of Bauxite, Garland County at Potash Sulphur Springs, and Hot Spring County at Magnet Cove. The total surface exposure of syenite in Arkansas is about 13 square miles (Arkansas Geological Commission 2006). Exposures of in Garland and Hot Spring counties have been disrupted by mining operations and may not contain extant examples of the system.
Geographic Range: Examples of this alliance are restricted to the Upper West Gulf Coastal Plain of Arkansas. There are also nepheline syenite outcrops in the adjacent Ouachitas, but these are not known to have extant glade communities.

Nations: US

States/Provinces:  AR


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.B Temperate & Boreal Grassland & Shrubland Subclass S18 2.B
Formation 2.B.2 Temperate Grassland & Shrubland Formation F012 2.B.2
Division 2.B.2.Nh Southeastern North American Grassland & Shrubland Division D102 2.B.2.Nh
Macrogroup 2.B.2.Nh.3 Poverty Dropseed - Little Bluestem - Calamint species Southern Barrens & Glade Macrogroup M308 2.B.2.Nh.3
Group 2.B.2.Nh.3.a Little Bluestem - Limestone Calamint - Nuttall''s Rayless-goldenrod Southeastern Coastal Plain Barrens & Glade Group G584 2.B.2.Nh.3.a
Alliance A4094 Rough Dropseed - Limestone Calamint - Carolina Larkspur Nepheline Syenite Bedrock Grassland Alliance A4094 2.B.2.Nh.3.a
Association CEGL008421 Rough Dropseed - Limestone Calamint - Atlantic Camas - Rockpink Fameflower / Lichens Nepheline Syenite Grassland CEGL008421 2.B.2.Nh.3.a
Association CEGL008422 (Post Oak) / Little Bluestem - Blackseed Speargrass - Arrowfeather Three-awn - Carolina Larkspur Nepheline Syenite Wooded Grassland CEGL008422 2.B.2.Nh.3.a
Concept Lineage: The two associations placed here are from A.1815 (1/6) and A.1920 (1/15).

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Nepheline Syenite Glade/Outcrop (Pell and Rettig 1983)
Concept Author(s): M. Pyne, in Faber-Langendoen et al. (2014)

Author of Description: M. Pyne

Acknowledgements: We have incorporated significant descriptive information previously compiled by T. Foti and D. Zollner.

Version Date: 03-14-14
  • Arkansas Geological Commission. 2006. Nepheline syenite. [http://www.state.ar.us/agc/novaculi.htm]. (accessed January 14, 2006)
  • 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.
  • Noss, R. F. 2013. Forgotten grasslands of the South: Natural history and conservation. Island Press, Washington, DC. 317 pp.
  • Pell, W. F., and J. H. Rettig, compiler. 1983. Arkansas natural community abstracts. Arkansas Natural Heritage Commission, Little Rock. 37 pp.