A. críspus, Braun. Very slender, procumbent, pubescent; leaves small, light green, rhombic-ovate to -lanceolate, acute, the margin crisped and undulate; flowers in small axillary clusters; bracts and sepals scarious, oblanceolate, acute or obtuse; utricle about as long, roughened, not nerved nor angled. (A. viridis, Man.)—Streets of Albany, New York City and Brooklyn; doubtless introduced, but the native habitat unknown.
Characters of Amarantus, except that the flowers are completely diœcious and the pistillate ones without calyx. Bracts 1–3, unequal. Staminate calyx of 5 thin oblong mucronate-tipped sepals, longer than the bracts; stamens 5, the anther-cells united only at the middle. Stigmas 2–5, often long and plumose-hispid. Fruit somewhat coriaceous and indehiscent, or a thin membranous utricle dehiscing irregularly (rarely circumscissile), usually 3–5-angled. (Name from α- privative, and κνίδη, a nettle.)
§ 1. ACNIDA proper. Fruit indehiscent, with firm and close pericarp.
1. A. cannábina, L. Usually stout, 2–6° high or more, glabrous; leaves lanceolate to linear-lanceolate, acuminate, long-petioled; sepals of sterile flowers ovate-oblong, obtuse or acutish; bracts usually thin and lax, much shorter than the fruit, sometimes more rigid and longer; fruit about 1´´ long, obovate, the pericarp rather thin, more or less rugosely angled; seed somewhat turgid, not angled, usually less than 1´´ long, shining.—Salt or brackish marshes, coast of N. Eng. to Fla.
2. A. rusocárpa, Michx. Very similar; fruit larger, 1½–2´´ long, the pericarp thicker, and the larger seed flattened with thick margins, usually thickest on the cotyledonar side.—N. Y. (?) and Penn. to S. Car.; apparently much less common than the last, though it is often difficult to positively distinguish the species from the immature fruit.
§ 2. MONTÈLIA. Fruit dehiscing irregularly, the pericarp thin, loose and usually roughened; not salt-marsh plants.
3. A. tuberculàta, Moq. Tall and erect, or sometimes low and decumbent; leaves lanceolate, acute or acutish or sometimes obtuse; sepals of sterile flowers lanceolate, acute or acuminate; pistillate flowers closely clustered in more or less dense naked or leafy axillary and terminal spikes (or the axillary capitate); bracts rather rigid, acuminate, equalling or exceeding the fruit; utricle about ½´´ long; seed shining, ½-{1/3}´´ in diameter. (Montelia tamariscina, Gray, in part.)—Ohio to Dak., Mo., Ala., and La.
Var. subnùda, Watson. Erect or often prostrate, the lower clusters at least of pistillate flowers more or less cymose and often in globose heads; bracts thinner, narrow and lax, shorter than the fruit. (M. tamariscína, var. concatenata, Gray, in part.)—W. Vt. (Oakes); Ont. to Minn., and southward. Often appearing quite distinct from the type, but intermediate forms are not rare.
3. IRESÌNE, P. Browne.