FWS Focus

Overview

Characteristics
Overview

Taxon: Plant 

Range: South Carolina, North Carolina, Virginia, Maryland, New Jersey, New York, Rhode Island (historic), Delaware and Massachusetts (recently reintroduced). 

Status: Threatened; listed April 7, 1993 

Seabeach amaranth is an annual plant native to U.S. Atlantic coast beaches. This plant is an indicator of a healthy beach ecosystem and contributes to coastal resiliency by helping to bind the sand. Well-adapted to its beach habitat, seabeach amaranth is highly tolerant of salt spray and able to grow in nearly pure sand but is intolerant of competing plants and most often occurs in areas with little other vegetation. By the 1980s, the species had vanished from 7 of the 9 states in its historic range. It has since made a remarkable comeback through natural seed dispersal as well as conservation efforts. Originally known from Massachusetts to South Carolina, it had not been observed north of Long Island, New York, in many years until a reintroduction to Nantucket Island and Monomoy National Wildlife Refuge on Cape Cod, Massachusetts in 2017. Several important threats remain including beach stabilizing structures such as groins, jetties, seawalls, and sand fencing; mechanical beach raking; vehicle use; intensive recreation; and rapid sea level rise.? Plant-eating animals such as webworms, white-tailed deer, sika deer and feral horses) may harm seabeach amaranth plants.  Natural disasters such as tropical storms and nor’easters can inundate or wash away plants before they set seeds. 

Partnerships, research and projects 

The U.S. Fish and Wildlife Service works with a variety of local, state and federal land managers to protect and monitor seabeach amaranth populations throughout the range of the species. Researchers at East Carolina University, North Carolina Botanical Garden, North Carolina State University, Raritan Valley Community College, University of North Carolina at Wilmington and Columbia University have conducted demographic and habitat research projects since the species was listed as threatened in 1993. 

The Service, in cooperation with the North Carolina Botanical Garden initiated a Cooperative Recovery Initiative project that involved planting seabeach amaranth on or near six national wildlife refuge national wildlife refuge
A national wildlife refuge is typically a contiguous area of land and water managed by the U.S. Fish and Wildlife Service  for the conservation and, where appropriate, restoration of fish, wildlife and plant resources and their habitats for the benefit of present and future generations of Americans.

Learn more about national wildlife refuge
throughout the historical range of the species. Approximately 2,000 seabeach amaranth seeds were planted at each refuge during May and June of 2017. Biologists and interns monitored the plots for germination, flowering and fruiting throughout the 2017 growing season and plan to conduct surveys for new Seabeach amaranth plants growing in the vicinity of those plots from 2018 to 2020. 

How you can help.

Beach Driving and pedestrian traffic could damage the plants. Avoid stepping on or driving over beach and dune vegetation. Avoid walking in areas specifically roped or fenced off for wildlife as seabeach amaranth often occurs in areas where Piping plovers and other shorebirds nest. 

Please report locations of seabeach amaranth to the Service’s lead recovery biologist, Dale_Suiter@fws.gov, and the appropriate state natural heritage program. 

 

Scientific Name

Amaranthus pumilus
Common Name
seaside amaranth
Seabeach amaranth
FWS Category
Flowering Plants
Kingdom

Location in Taxonomic Tree

Identification Numbers

TSN:

Characteristics

Characteristic category

Similar Species

Characteristics
Similar Species

Seaside spurge (Chamaesyce polygonifolia) is a close vegetative associate of seabeach amaranth. These two species share a low growth form and reddish stems. However, the leaves of seaside spurge are lighter green, more elongated, and less shiny than seabeach amaranth. 

Characteristic category

Habitat

Characteristics
Habitat

Seabeach amaranth occurs on barrier beaches, where its primary habitat consists of overwash flats at the ends of islands that are accumulating more sand and lower developing dunes and upper strands of non-eroding beaches. It occasionally establishes small temporary populations in other habitats, including sound-side beaches, overwash areas in developing dunes, and sand and shell material placed as beach replenishment or dredge spoil. Seabeach amaranth appears to be intolerant of competition and does not occur on well-vegetated sites. The species appears to need extensive areas of barrier island beaches and inlets that are not stabilized by perennial vegetation. These characteristics allow it to move around in the landscape as a fugitive species, occupying suitable habitat as it becomes available. The species is an effective sand binder, building small dunes where it grows. 

Coastal

The land near a shore.

Characteristic category

Physical Characteristics

Characteristics
Size & Shape

Seabeach amaranth has stems that are fleshy and pinkish-red or red, with small, rounded leaves that are 0.5 – 1 inch (in) (1.3 - 2.5 centimeters; cm) in diameter. The leaves, with indented veins, are clustered toward the tip of the stem and have a small notch at the rounded tip. Flowers and fruits are relatively inconspicuous, borne in clusters along the stems. Germination occurs over a relatively long period of time, generally from April to July. Upon germination, the species forms a small unbranched sprig, but soon begins to branch profusely into a clump. This clump often reaches 30 cm in diameter and consists of five to 20 branches. Occasionally, a plant may grow as large as a meter or more across. 

Characteristic category

Life Cycle

Characteristics
Reproduction

Seabeach amaranth shows good reproductive success in the years when no major storm events occur. Seed output is correlated with plant size, with large plants estimated to produce several thousand fertile seeds over the course of a growing season. Based on the morphology of the flower and inflorescence, seabeach amaranth is considered to be wind-pollinated. Based on observed seed production by single isolated individuals, it is clear that seabeach amaranth is capable of self-pollination. 

Seabeach amaranth seems to "hedge its bets" with regard to seed dispersal, which is primarily via wind and water. To increase the odds that at least some of its offspring are likely to end up in  favorable habitat in future years, this species employees a three-part strategy of long-distance dispersal, short-distance dispersal, and "planting." Long-distance dispersal is achieved by some seeds that detach from the parent plant but remain in low-density capsules called utricles, which also include an air pocket. Borne by wind and currents, seed-filled utricles are able to disperse across inlets and long stretches of unsuitable habitat. Long-distance dispersal probably takes place primarily during storm events such as fall hurricanes and winter northeasters. Short-distance dispersal is achieved by other seeds that are released from the utricle as it becomes split or abraded by sand. These "naked" seeds are also dispersed by wind but to a much lesser degree than utricles, behaving like large, low-density sand grains. Naked seeds typically remain in the lee of the parent plant or get deposited in a nearby depression, usually within 300 feet of the parent plant. Seeds may often be observed to pile up around the bases of the parent plants, particularly larger individuals. Finally, some seeds remain within the utricle and attached to the plant and are never dispersed, getting "planted" as the dead or dying parent plant is buried by blowing sand at the end of the season.

Life Span

The maximum lifespan of a seabeach amaranth plant is about 8 months, though many plants do not persist that long. This species overwinters as seeds, which are believed to be capable of persisting in the beach environment for many years until suitable conditions for gemmation are present.  

Life Cycle

Upon germinating, seabeach amaranth initially forms a small reddish, upright spring. Soon the seedling begins to branch into a low-growing rosette consisting of 5 to 20 branches and typically reaching 4 to 12 inches in diameter. Occasionally a plant may reach a yard or more across, with a hundred or more branches. The stems are fleshy and pink-red or reddish, with small rounded leaves. Clustered toward the tip of the stem, the leaves are somewhat shiny, spinach-green in color, and have a small notch at the tip. Small white flowers and dark seeds are located in inconspicuous clusters along the stems. As they age throughout the fall, plants often turn reddish or purplish, and some stems and leaves may die back.

Seabeach amaranth germination takes place over a relatively long period, beginning as early as April in the south and starting in mid-May or early June farther north. Germination continues at least through July. Flowering begins as soon as plants have reached sufficient size, sometimes as early as June in the Carolinas but more typically commencing in July. Flowering continues until the plant dies in late fall or early winter. Seed production begins in July or August and reaches a peak in most years in September; seeding likewise continues until the plant dies. Seabeach amaranth plants that are not lost to burial or flooding from fall storms may persist through November in the north, and into January farther south. 

Geography

Characteristics
Range

Historical range

Historically, seabeach amaranth occurred in nine states along the northeast and mid-Atlantic coast from Massachusetts to South Carolina (excluding Connecticut).

Current range

Natural populations of seabeach amaranth currently occur in New York, New Jersey, Delaware, Maryland, Virginia, North Carolina, and South Carolina. Seabeach amaranth was recently planted on Nantucket Island and at Monomoy National Wildlife Refuge, both in Massachusetts.

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