Overwash Plains and Coastal Berms

The Palmetto Quarterly Magazine of the Florida Native Plant Society • Vol. 6, No. 1 • Spring 1986

Florida’s Natural Communities OVERWASH PLAINS AND COASTAL BERMS

by Linda Conway Duever

Sometimes we don’t recognize a are among the soil types. These sites are Juncus brachycarpus, Eragrostis purshii, natural community that is genuinely prime nesting habitat for terns, skimmers, Panicum repens, Fimbrystilis castanea, native to Florida just because it looks like and other shore birds that nest on bare Cyperus rotundus, Dicanthelium acu- the second growth that results from ground. minatum, Batis maritime, Opuntia stricta, human disturbance. This is particularly The vegetation includes a vast and Limonium carolinianum. likely to happen along the coast where assortment of dune and salt marsh species Coastal Berms are old marine bars hurricane trauma leaves scars that as well as both native and exotic weeds. from times of higher sea level and/or resemble old development wounds. And Since these are by nature disturbed sites, places where storms have thrown up Overwash Plains and Coastal Berms are they are among the natural communities ridges of sand, shell, and debris. They are the storm-created habitats we’re most most readily colonized by exotics. most common along the southwest likely to overlook. Typical native plants include slash pine, Florida coast where they often take the Overwash Plains are the low sand Pinus elliotii; sea oats, Uniola pa- place of dunes. (This coast doesn’t get flats left where storm waves have washed niculata; beach cordgrass, Spartina everyday winds powerful enough to build across a barrier island. There’s a lot of patens; little bluestem, Schizachryium up genuine dune systems like those along loose sand, perhaps piled into dunelets scoparium;dropseed, Sporobolus virgin- the east coast or the Panhandle.) These and/or divided by sluiceways, and usually icus; sandspur, Cenchrus tribuloides; features are called by different names in scattered weedy shrubs and herbs. After beach elder, Iva imbricata; railroad vine, different types of locations. In the the site has gone for an extended period Ipomoea pes-caprae; sea purslane, Sesu- mangroves, they can be buttonwood without storm scouring, the vegetation vium portulacastum; saltwort, Salicornia embankments, mangrove hammocks, may develop into a dense mat of vines virginica; beach orach, Atriplex arenaria; coastal levees, or coastal forests. Behind and grasses, then, eventually, into pine sea blite, Suaeda linearis; seaside a beach, they are shell ridges. flatwoods. evening primrose, Oenothera humifusa; Coastal Berms support a wide variety The flatwoods on old Overwash beach spurge, Chamaesyce mesem- of vegetation types because the materials Plains tend to be denser than most bryanthemifolia; seaside pennywort, that constitute them can be so varied. The because the barrier island location Hydrocotyle bonariensis; marsh sam- soils are often composed of many layers protects them from spreading fires, so phire, Philoxerus vermicularis; and of peat, shell, sand, and woody debris they don’t burn as often. The literature seaside ground cherry, Physalis viscosa. deposited by different storms. presents contradictory views as to how Since the habitat is so often ignored Most commonly, the vegetation much overwash and sand deposition an or lumped or confused with another, there consists of a dense thicket of large shrubs established pineland can take. Some are very few plant lists specific to the and small contorted trees with the interior authors recount instances where the pines community. Other species I have en- cluttered with branches, roots, and debris, proved extremely sensitive, whereas countered in such data – and some of but it may be a full-fledged hammock, a others contend they’ve seen them keep these may be taxonomically questionable savanna, or a sparse desert-like shrub right on growing vigorously, even with – include Chamaesyce bombensis, Cy- community. Florida Natural Areas Inven- sand piled thirty or forty feet high around perus planifolius, Dactyloctenium, aegyp- tory has documented five Coastal Berm them. tium, Borrichia frutescens, Cynachum plant communities: Tropical Coastal Overwash Plain soils are composed palustre, Ipomoea indica, Sporobolus Hammock , Keys Dune Hammock, of sand and shell with some organic domingensis, Opuntia compressa, C- Buttonwood Levee, Agave Barren, and debris mixed in. Kesson and Canaveral yperus lecontei, Juncus dichotomus, Bouteloua Savanna. The Agave Barrens are particularly Hammock communities are liable to interesting botanically. These shelly include white stopper, Eugenia axillaris; mounds, which could easily be confused strangler fig, Ficus aurea; Spanish with spoil piles, have scattered clumps of stopper, Eugenia foetida; live oak, cacti and other drought-and salt-tolerant Quercus virginiana; gumbo limbo, Bur- shrubs and herbs. Necklace-pod, Sophora sera simaruba; wild coffee, Psychotria tomentosa; forestiera, Forestiera seg- nervosa; serpent fern, Phlebodium aur- regata; beach creeper, Ernodea lit- eum; and whisk fern, Psilotum nudum. ABOUT THE AUTHOR: Linda Duever is a long- toralis; and agave, Agave decipiens, are Unfortunately, Brazilian pepper, Schinum time FNPS member. Today she is president characteristic species. terebinthifolius is also a common species and principal ecologist of Conway Consulting in The interior of Cayo Costa Island is a here. Gainesville. Her posters of Florida native plant communities can be obtained by contacting her broad Coastal Berm covered by a unique Some of the rare species that occur at [email protected]. Bouteloua Savanna dominated by hairy on Overwash Plains, Coastal Berms, and grama grass, Bouteloua hirsuta. This Shell Mounds (described in The Pal- species is common in the west, but grows metto, Winter, 1985/86), submitted by nowhere east of the Mississippi except on Dennis Hardin, botanist with FNAI, are: Coastal Berms along the southwest golden leather fern, Acrostichum aureum; Florida Coast. iguana hackberry, Celtis iguanaea; spiny Other typical Coastal Berm plants hackberry, Celtis pallida; fragrant wooly include cabbage palm, Sabal palmetto; cactus, Cereus eriophorus var. fragrans; seagrape, Coccoloba uvifera; button- southern lip fern, Chelilanthes micro- wood, Conocarpus erecta; saltbush, phylla; ghost orchid, Polyrrhiza lindenii; Suggested citation for this article

Baccharis halimifolia; beach elder, Iva buckthorn, Sageretia minutiflora; beach- Deuver, L. C. 1986. Florida’s Natural imbricata; scrub briar, Smilax auriculata; creeper, Ernodea littoralis; red stopper, Communities: Overwash Plains and prickly pear, Opuntia compressa; poison Eugenia rhombea; joewood, Jacquinia Coastal Berms. The Palmetto, 6(1):10-11. ivy, Toxicodendron radicans; Spanish keyensis; and bay cedar, Suriana mar- http://www.fnps.org/palmetto/v06i1p10due bayonet, Yucca aloifolia; love vine, itime. ver.pdf

Cassytha filiformis; lantana, Lantana Most of these species could occur in Articles from The Palmetto that appear on this involucrate and L. ovatifolia; barbed-wire any of the three natural communities of website may be used in portion or entirely for cactus, Cerus pentagonus; snowberry, Coastal Mounds. non-commercial, informational or educational Chiococca alba; hairgrass, Muhlenbergia Though Coastal Berms and Over- purposes, provided complete and accurate capillaris; tread-softly, Cnidoscolus wash Plains are too vulnerable to hur- citation accompanies all usage. Citation must stimulosus; varnish leaf, Dodonea vis- ricanes to be safe building sites, they are include authorship, photo credits, and the cosa; sea daisy, Borrichia frutescens; endangered by development pressure website of the Florida Native Plant Society as coral bean, Erythina herbacea; and wax because they occur on high-priced coastal the source of publication. myrtle, Myrica cerifera. Most Overwash real estate. And they are all the more Plain species also occur in open Coastal vulnerable because they don’t look like

Berm environments. anything special.