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African amaranth, muricate amaranth

smartweed amaranth, tropical amaranth

Habit Plants annual or short-lived perennial, glabrous or slightly pubescent near tips. Plants annual, glabrescent proximally, pubescent distally, becoming glabrous at maturity.
Stems

ascending or prostrate, much-branched from stout rootstock, 0.1–0.4 m.

erect-ascending to prostrate, branched mostly at base and in proximal 1/2, 0.1–0.5 m.

Leaves

petiole to 1/2 as long as blade;

blade linear to narrowly lanceolate, 1.5–8 × 0.2–0.5(–1) mm, base tapering, margins entire, plane to undulate, apex obtuse and often emarginate.

petiole ± equaling blade;

blade ovate, obovate-rhombic to narrowly ovate, sometimes lanceolate, 1.5–3(–4) × 0.5–1.5(–2) cm, base cuneate, margins entire to undulate-erose, apex rounded, obtuse, or emarginate, mucronate.

Bracts

of pistillate flowers linear, 0.7–1.2 mm, 1/2–2/3 as long as tepals.

of pistillate flowers lanceolate or linear, 1–1.5 mm, 1/2 as long as tepals.

Inflorescences

terminal, compact pyramidal panicles and axillary glomerules, erect or reflexed, green, leafless at least distally.

axillary, congested clusters.

Staminate flowers

intermixed with pistillate or at tips of inflorescences;

tepals 5;

stamens 5.

intermixed with pistillate;

tepals (4–)5;

stamens 2–3.

Pistillate flowers

tepals 5, narrowly oblanceolate, not clawed, equal, 1.5–2 mm, apex obtuse or subacute;

style branches erect;

stigmas 3.

tepals 5, connate in proximal 1/3 (entirely distinct in all other species), with 3 prominent veins abaxially, spatulate or somewhat clawed, equal or subequal, 2–3 mm, apex rounded or retuse, mucronate;

style branches somewhat spreading;

stigmas 3.

Seeds

black, lenticular, 1–1.2 mm diam., semiglossy.

dark reddish brown to black, lenticular, 0.8–1 mm diam., shiny.

Utricles

compressed, subglobose, 1.7–2 mm, ± equaling or slightly exceeding tepals, muricate, indehiscent.

cylindric or narrowly turbinate, 2–2.5 mm, ± equaling tepals, smooth proximally or roughened toward tips, indehiscent or tardily dehiscent.

Amaranthus muricatus

Amaranthus polygonoides

Phenology Flowering summer–fall. Flowering summer–fall.
Habitat Waste places, on ballast Disturbed habitats, coastal areas, near wool-combing mills
Elevation 0 m (0 ft) 0-500 m (0-1600 ft)
Distribution
from FNA
AL; s South America (Argentina, Paraguay, Uruguay) [Introduced in North America; introduced in s Europe, s Africa, Australia, and other regions]
[BONAP county map]
from FNA
FL; SC; TX; Mexico; West Indies; n South America [Rarely introduced in Europe and some other regions]
[BONAP county map]
Discussion

The vernacular name “African amaranth” is sometimes used for this species; it is a misnomer; the species is native to South America and naturalized in Africa.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Amaranthus berlandieri often has been recognized as a separate species related to A. polygonoides. J. Henrickson (1999) clarified the confusion that existed in earlier descriptions of these two taxa and showed that the main characters used for their separation (dehiscent versus indehiscent utricles, leaf shape, etc.) are inconsistent and cannot be applied for segregation of two independent species. The subspecies rank may be more appropriate for A. berlandieri, as was suggested by A. Thellung (1914–1919). The relationships between these taxa of the A. polygoniodes aggregate require additional study; in the present treatment we follow the solution proposed by Henrickson.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 4, p. 431. FNA vol. 4, p. 432.
Parent taxa Amaranthaceae > Amaranthus > subg. Albersia Amaranthaceae > Amaranthus > subg. Albersia
Sibling taxa
A. acanthochiton, A. albus, A. arenicola, A. australis, A. blitoides, A. blitum, A. californicus, A. cannabinus, A. caudatus, A. crassipes, A. crispus, A. cruentus, A. deflexus, A. dubius, A. fimbriatus, A. floridanus, A. graecizans, A. greggii, A. hybridus, A. hypochondriacus, A. obcordatus, A. palmeri, A. polygonoides, A. powellii, A. pumilus, A. retroflexus, A. scleropoides, A. spinosus, A. tamaulipensis, A. thunbergii, A. torreyi, A. tricolor, A. tuberculatus, A. viridis, A. viscidulus, A. watsonii, A. wrightii
A. acanthochiton, A. albus, A. arenicola, A. australis, A. blitoides, A. blitum, A. californicus, A. cannabinus, A. caudatus, A. crassipes, A. crispus, A. cruentus, A. deflexus, A. dubius, A. fimbriatus, A. floridanus, A. graecizans, A. greggii, A. hybridus, A. hypochondriacus, A. muricatus, A. obcordatus, A. palmeri, A. powellii, A. pumilus, A. retroflexus, A. scleropoides, A. spinosus, A. tamaulipensis, A. thunbergii, A. torreyi, A. tricolor, A. tuberculatus, A. viridis, A. viscidulus, A. watsonii, A. wrightii
Synonyms Euxolus muricatus A. berlandieri
Name authority (Moquin-Tandon) Hieronymus: Pl. Diaph. Fl. Argent., 227. (1882) Linnaeus: Pl. Jamaic. Pug., 27. (1759)
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