GULF OF MEXICO 



199 



railroad vines, Scaevola plumieri Vahl, beach 

 berry, Andropogon glomeratus (Walt.) BSP., 

 bunehgrass, Cenchrtis pauciflorus Benth., sandbur, 

 Croton punctafus Jaeq., silverleaf, Oenothera humi- 

 fusa Nutt., seaside evening-primrose, and Helian- 

 thv,<! debilis Nutt., dune sunflower. 



Many of these speeies, especially the dominant, 

 graceful sea-oats, Uniola, remain abundant in the 

 back dunes and dune plateaus inland from the 

 beach. Here, however, the conspicuous speeies 

 are the larger plants like Coccoloha udfera (L.) 

 Jacq., the seagrape, which is the most character- 

 istic shrub of sandy strands in the American 

 tropics. Other woody species are Yucca aloifolia 

 L., Spanish-bayonet, Forestiera porulosa (Michx.) 

 Poir., Florida privet, Chiococca alba (L.) A. 

 Hitchc, snowberry, Ernodea littoralis Sw., Myrica 

 cerifera L., waxmyrtle, Sabal palmetto (Walt.) 

 Todd., cabbage palm, Suriana maritima L., bay- 

 cedar, Lantana ovatifolia Britt., slu-ub-verbena, 

 Sophora tomentosa L., necklace-pod, Dalbergia 

 ecastophylium L., coin-vine, Canavalia obtusifolia 

 (Lam.) DC, bay bean, Zanthoiylum clava-he.r- 

 culis L., toothache tree, Rapanea guianensis 

 Aubl., mjTsine, Ardisia escallonioides Schlecht. & 

 Cham., marlberry, and Eugenia axillaris (Sw.) 

 Willd., white stopper. Most of these beaches 

 and dunes along the central Florida coast are on 

 narrow barrier islands which are covered with 

 strand vegetation on the Gulf side and mangrove 

 thicket on the bay side. Between these two types 

 of vegetation ma}' be developed a grassy palm 

 savannah with Sabal dominant or a dense coastal 

 hammock composed of more luxuriant and crowdcnl 

 growth of the same species listed above for the 

 back dunes. 



Along the northern Gulf coast many of the 

 tropical elements of the dunes and dune-plateau 

 drop out. On the other hand, some of the tem- 

 perate species are replaced by more tropical spe- 

 cies on the Florida Keys and northwestern coast 

 of Cuba. Among the more important additions 

 to the strand flora there are Tournefortia gnapha- 

 lodes (Jacq.) R. Br., sea-lavender, Casasia clusii- 

 folia (Jacq.) Urban, seven-year-apple, Erithalis 

 fruticosa L., Strumpfia marifirna Jacq., Chryso- 

 balanun icaco L., coco-plum, and the less common, 

 poisonous Hippomane mancinella L., manchineel. 

 Most of the strand species are widely distributed 

 throughout the tropics, and a few, like Ipnmoea 

 pes-caprae (L.) Sweet are circumtropical. One ex- 



otic tree from Oceaniea, fafiuarina equiMtifolia 

 Forst., Australian-pine or beef wood, has become 

 widely naturalized on the sandy shores of penin- 

 sular Florida a7ul the West Indies. On some of 

 the Florida beaches it is the dominant tree. 



Most of the abundant species of the Florida and 

 Cuba beaches and dunes are listed from Yucatan, 

 and the strand vegetation along the rest of the 

 Mexican Gulf coast is probably similar to that of 

 the southeastern shores of the Gulf. Little seems 

 to have been published on the vegetation of the 

 Texas coast, but there, too, the strand flora must 

 be rather similar to that of the Florida coast in 

 the same latitude. 



CONCLUSION 



The vegetation of the shallow waters and 

 shores of the Gulf of Mexico includes four principal 

 communities of flowering plants. Throughout 

 the Gulf a cliaracteristic strand flora grows on 

 exposed sandy shores of the fringing barrier islands, 

 the larger bays, and the headlands. Grass-like 

 marine spermatophytes form submarine meadows 

 or carpets in shallow, quiet waters, except along 

 the extreme northern Gulf coast. Extensive salt 

 marshes cover muddy, protected shores in lagoons, 

 bays, and estuaries along the northern Gulf 

 coasts. Protected shores in the central and south- 

 ern Gulf region, however, support swamps or 

 thickets dominated by mangroves, with slU- 

 niarsh plants restricted to small areas of open 

 marsh, to open saline flats, or to the understory of 

 the more open zones of- the mangrove swamps. 



Knowledge of the flora and vegetation of most 

 of the Gulf shores is relatively meager. Only 

 the coast from Louisiana to the Florida Keys has 

 received considerable attention from botanists. 

 The Cuban and Texan coasts have largely been 

 neglected, and the Mexican coast, excluding 

 Yucatan, has received almost no botanical at- 

 tention. The whole Gulf perimeter should be 

 subjected to an intensive, systematic survey by 

 competent plant taxonomists and ecologists. 



BIBLIOGRAPHY 



ASCHERSON, P. 



1906. Die geographische Verbreituiig der Seegraser. 

 In Neumayer, Anleitung zu wissenschaftlichen 

 Beobachtungen auf Reisen. Ed. 3, 2: 389-413. 

 Hannover. 



A.SCHERSON, P., and Graebner, P. 



1907. Potamogetonaceae. In Engler, Pflanzenreich 

 4 (11): 1-184, figs. 1-36. 



