Print Report

A3578 Panicum hemitomon Floating Marsh Alliance

Type Concept Sentence: These are freshwater or tidal flotant marshes dominated by Panicum hemitomon or Morella cerifera, found in the Chenier and Deltaic plains of Louisiana and the upper coast of Texas.

Common (Translated Scientific) Name: Maidencane Floating Marsh Alliance

Colloquial Name: Maidencane Floating Marsh

Hierarchy Level:  Alliance

Type Concept: These flotant marshes are dominated by Panicum hemitomon or Morella cerifera. These marshes are primarily freshwater, and may be tidal in some areas. This is a very common fresh marsh type of the Chenier and Deltaic plains of Louisiana and the upper coast of Texas. Spikerush marshes, dominated by Eleocharis baldwinii and Hydrocotyle spp., are also included here. The shrub-dominated version of this marsh apparently arises from woody plant succession in the Panicum hemitomon-dominated marshes in the absence of fire. As the shrubs develop and mature, they weigh down the floating peat mat, submerging it and eventually killing the shrubs.

Diagnostic Characteristics: These flotant marshes are dominated by Panicum hemitomon or Morella cerifera. They are primarily freshwater, and may be tidal in some areas. This is a very common fresh marsh type of the Chenier and Deltaic plains of Louisiana and the upper coast of Texas.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: The marsh dominated by Morella cerifera with Panicum hemitomon is included here, as it is part of the same larger landscape of the Mississippi Deltaic Plain, and is very close floristically to the Panicum hemitomon-dominated marshes. Spikerush marshes, dominated by Eleocharis baldwinii and Hydrocotyle spp., are also included here. This vegetation has been recognized in Louisiana in the Deltaic Plain, and is apparently increasing in area.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Panicum hemitomon is a coarse perennial grass standing about a meter tall. Some stands also contain the evergreen shrub Morella cerifera. Spikerush marsh (included here) is codominated by Eleocharis baldwinii and Hydrocotyle spp.

Floristics: Stands of this alliance are dominated by Panicum hemitomon, a coarse perennial grass standing about a meter tall. Some stands also contain Morella cerifera. Members of the genera Eleocharis, Rhynchospora, Xyris, Juncus, Carex, Typha, Hydrocotyle, Cladium and Ludwigia may also be present. Spikerush marsh (included here) is codominated by Eleocharis baldwinii and Hydrocotyle spp., mainly Hydrocotyle ranunculoides and Hydrocotyle umbellata; Bidens laevis is a frequent codominant. Species richness in this marsh type is moderate. Some other commonly occurring species include Typha spp., Sagittaria lancifolia, Eleocharis spp., Panicum hemitomon, Sagittaria latifolia, Ludwigia spp., Decodon verticillatus, Rhynchospora colorata (= Dichromena colorata), Sacciolepis striata, Zizaniopsis miliacea, and others.

Dynamics:  These marshes are maintained in herbaceous condition by burning in the fall, when unburned they develop a shrub layer of Morella cerifera. This shrub community may revert to herbaceous condition after the shrub layer develops enough mass to weigh down the floating mat causing submergence and eventual shrub mortality (Sasser et al. 1996). Localized examples of his association, north of Lake Pontchartrain in Louisiana dominated by Panicum hemitomon and Orontium aquaticum, are surrounded by Taxodium spp. forests, and widely scattered Taxodium ascendens occurs in these examples. These marshes, located further inland, are less influenced by the current deltaic processes and may reflect a condition of this association prior to deltaic subsidence and subsequent flotant formation. Fresh Spikerush Marsh vegetation, included here, appears to represent degraded Fresh Maidencane Marsh. It is postulated that Fresh Maidencane Marsh may convert to Fresh Spikerush Marsh as a consequence of intense herbivory (by nutria [or muskrat?]), changes in hydrology, changes in water quality, certain fire regimes or other factors.
Environmental Description:  These are floating marshes of the Mississippi Deltaic Plain occurring on extensive floating peat mats. The shrub-dominated version of this marsh apparently arises from woody plant succession in the Panicum hemitomon-dominated marshes in the absence of fire (Sasser et al. 1996). As the shrubs develop and mature, they weigh down the floating peat mat, submerging it and eventually killing the shrubs.
Geographic Range: This is a common marsh type of the Chenier and Deltaic plains of Louisiana and the upper coast of Texas.

Nations: US

States/Provinces:  LA, TX


Confidence Level: Moderate

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.Ne Atlantic & Gulf Coastal Marsh, Wet Meadow & Shrubland Division D322 2.C.4.Ne
Macrogroup 2.C.4.Ne.1 Annual Wild Rice - Saltmeadow Cordgrass - Pickerelweed Fresh-Oligohaline Tidal Marsh Macrogroup M066 2.C.4.Ne.1
Group 2.C.4.Ne.1.b <i>Zizaniopsis milacea - Spartina patens - Panicum hemotimon</i> Freshwater Tidal Marsh Group G913 2.C.4.Ne.1.b
Alliance A3578 Maidencane Floating Marsh Alliance A3578 2.C.4.Ne.1.b
Association CEGL004665 Maidencane Marsh CEGL004665 2.C.4.Ne.1.b
Association CEGL007834 Wax-myrtle - Maidencane Floating Marsh CEGL007834 2.C.4.Ne.1.b
Concept Lineage: Dynamics (pasted in from CEGL004665). These associations come from the old alliances A1379 (1/13) and A.1988 (1/1).

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: >< Fresh Marsh (Smith 1999)
>< IIE1f. Coastal Plain Small Depression Pond Complex (Allard 1990)
Concept Author(s): C. Nordman, in Faber-Langendoen et al. (2013)

Author of Description: M. Pyne

Acknowledgements: We have incorporated significant information developed and compiled by D.J. Allard, J. Teague, and L.M. Smith.

Version Date: 12-18-14
  • Allard, D. J. 1990. Southeastern United States ecological community classification. Interim report, Version 1.2. The Nature Conservancy, Southeast Regional Office, Chapel Hill, NC. 96 pp.
  • 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.
  • LNHP [Louisiana Natural Heritage Program]. 2009. Natural communities of Louisiana. Louisiana Natural Heritage Program, Louisiana Department of Wildlife & Fisheries, Baton Rouge. 46 pp. [http://www.wlf.louisiana.gov/sites/default/files/pdf/page_wildlife/6776-Rare%20Natural%20Communities/LA_NAT_COM.pdf]
  • Sasser, C. E., J. G. Gosselink, E. M. Swenson, M. Swarzenski, and N. C. Leibowitz. 1996. Vegetation, substrate and hydrology in floating marshes in the Mississippi River delta plain wetlands, USA. Vegetatio 122:129-142.
  • Smith, L. 1999. Coastal marsh types currently recognized in Louisiana and relationships with existing types in ICEC-TNC. Draft report. Louisiana Department of Wildlife and Fisheries, Natural Heritage Program, Baton Rouge. 20 pp.
  • Smith, L. M. 1996b. The rare and sensitive natural wetland plant communities of interior Louisiana. Unpublished document. Louisiana Department of Wildlife and Fisheries, Louisiana Natural Heritage Program, Baton Rouge. 38 pp.
  • Visser, J. M., C. E. Sasser, R. H. Chabreck, and R. G. Linscombe. 1998. Marsh vegetation types of the Mississippi River Deltaic Plain. Estuaries 21(48):818-828.
  • Visser, J. M., and C. E. Sasser. 1998. 1997 Coastal vegetation analysis. Unpublished report to Greg Steyer, Louisiana Department of Natural Resources, Baton Rouge, LA. Draft report November 20, 1998. 47 pp.