The Gulf coast can be broadly divided into beach, embryo dunes, foredunes, blowouts, active dunes, wet and humid dune slacks and dry dunes. Overall they supports some 58 dune community types (Moreno-Casasola & Espejel 1981).

Beach (Pioneer Zone)
This zone, which is often subject to damaging hurricanes and inundation from sea water and flooding from nearby rivers, is dominated exlusively by annual species.  These help bind sand but do not form embryo dunes. Species composition and dominance varies but typical dominants includes Amaranthus greggii, Cakile edentula, Cakile geniculata, Ipomoea stolonifera, Okenia hypogaea and Sporobolus virginicus.

Embryo Dunes and Foredunes
Species composition of embryo dunes and foredunes are similar, but they all constitute species that can tolerate large amounts of sand accretion and salt spray, and share an ability to trap sand. Some of the more dominant species include Bidens pilosa, Canavalia rosea, Croton punctatus, Heliotropium curassavicum, Ipomoea pes-caprae, Ipomoea stolonifera, Oenothera drummondii, Panicum geminatum, Sesuvium portulacastrum, Sporobolus virginicus, Uniola paniculata, and the endemic Palafoxia lindenii (Asteraceae). The latter is a tall shrub that can form monospecific stands in places.

Blowout and Active Dunes
These are area of high mobility and low organic content. Typical species include Acacia cornigera, Andropogon scoparius var. littoralis, Chamaecrista chamaecristoides and Commelina erecta. The small shrub Chamaecrista chamaecristoides is considered to be endemic to the Gulf of Mexico. Nevetheless, it is one of the most widespread species in the Gulf area and one of the most important dune fixers.

Humid and Wet Slacks
These develop where the ground water is close to the surface. Species composition and dominance varies, but some of the more typical dominants include Bidens pilosa, Borrichia frutescens, Chamaesyce dioica, Conocarpus erecta, Cyperus articulatus, Eleocharis cellulosa, Eleocharis geniculata, Erigeron myrionactis, Fimbristylis castanea, Fimbristylis spathacea, Hydrocotyle bonariensis, Lippia nodiflora and Panicum repens.

Fixed Dunes
In the Gulf these more stable dune areas are far more complex than in temperate dune systems, and can be divided forb dominated communities, grass dominated communities, low shrub dominated communities, spiny shrub dominated communities and high thickets.

Forb Dominated Fixed Dunes
Depending on location the dominant species may include either Macroptilium atropurpureum or Schrankia quadrivalvis.

Grass Dominated Fixed Dunes
Depending on location the dominant species may include Aristida adscensionis, Aristida roemeriana, Aristida curvifolia, Bouteloua repens, Eustachys petraea, Sporobolus jacquemonti or the endemic Trachypogon gouini.

Low Shrub Dominated Fixed Dunes
Depending on location the dominant species may include Ambrosia artemisiifolia, Pectis saturejoides, Stemodia tomentosa, Palafoxia texana var. robusta, Tamonea curassavica or Waltheria indica.

Spiny Shrub Dominated Fixed Dunes
These are often associated with sheltered areas of beach-ridge systems. Depending on location the dominant species may include Acacia macracantha, Acacia farnesiana, Caesalpinia bonduc, Opuntia stricta var. dillenii or Randia laetevirens. The latter is the most widespread of the spiny shrubs forming thickets of between 1-3 m tall.

High Thicket Dominated Fixed Dunes
Depending on location the dominant species may include Chrysobalanus icaco, Coccoloba barbadensis, Crossopetalum uragoga, Dalea scandens, Diphysa robinioides, Eupatorium odoratum, Hibiscus pernabuscensis, Lantana camara, Nectandra coriacea, Psidium guajava, Schaefferia frutescens and Verbesina persicifolia.


Moreno-Casasola, P & Espejel, I. 1981. Classification and ordination of coastal sand dunes vegetation along the Gulf and Caribbean Sea of Mexico. Vegetatio, 66, 147-182.