Amaranthus pumilus

Plants annual, glabrous. Stems prostrate to ascending (often forming mats), red, much-branched, 0.1–0.4 (–0.5) m, fleshy. Leaves clustered near tips of branches; petiole 5–10 mm; blade orbiculate, broadly ovate or obovate, 1–1.5 cm × 1–1.5 cm, fleshy, base broadly cuneate to tapering, margin entire, plane or slightly undulate, apex broadly rounded to obtuse, mucronate. Inflorescences dense axillary glomerules, green. Bracts of pistillate flowers ovate or elliptic, 1.2–2 mm, 1/2 as long as tepals. Pistillate flowers: tepals 5, linear to narrowly oblanceolate, slightly unequal, 2.5–4 mm, margins entire, apex obtuse; style-branches erect; stigmas 3. Staminate flowers intermixed with pistillate; tepals 5; stamens 5. Utricles ovoid, 4–6 mm, exceeding tepals, fleshy, smooth or slightly rugose, longitudinally wrinkled on drying, indehiscent. Seeds dark reddish-brown, lenticular, 2.5 mm diam., glossy.

Phenology: Flowering summer–fall.
Habitat: Maritime sand dunes, beaches, mostly on foredunes and at high tide level
Elevation: 0-10 m

Conn., Del., Md., Mass., N.J., N.Y., N.C., Pa., R.I., S.C., Va.

Discussion

Of conservation concern.

Amaranthus pumilus is a globally and federally threatened species (Global Heritage Status Rank G2; National Heritage Status Rank N2) originally restricted to dunes and barrier island beaches along the Atlantic Ocean from southern Massachusetts to South Carolina. It has been eliminated from two-thirds of its former range, being last reported from Massachusetts in 1849, from Rhode Island in 1856, from New Jersey in 1913, and from Virginia in 1972 (S. Ramsey et al. 2000). As of fall 2003, extant populations are known only from Long Island, New York, Delaware, Maryland, North Carolina, and South Carolia. Many threats exist, including construction of sea walls and dune fencing, development, heavy recreational use, and off-road vehicle traffic. It is difficult to afford protection because of the dynamic nature of the habitat and the fugitive nature of the biology of the species. “Fugitive” refers to the fact that the species does not necessarily occur throughout its potential range at any given time (S. E. Clemants 1992).

Amaranthus pumilus is in the Center for Plant Conservation’s National Collection of Endangered Plants.

Selected References

None.

Lower Taxa