Contains 15 accepted taxa overall.

Characteristics
Amaranthus L.
AMARANTH
Classification
CARYOPHYLLALES
Amaranthus
Citation
AMARANTHUS Linnaeus, Sp. Pl. 989. 1753.
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TYPE: Amaranthus caudatus Linnaeus Lectotypified by Britton & A. Brown, Ill. Fl. N. U.S., ed. 2. 2: 1. 1913.
Distribution Map Present

This species have been reported in the counties highlighted.

Species
Scientific Name Common Name Herbarium Specimens Status Photos
Amaranthus albus PROSTRATE PIGWEED; TUMBLEWEED Not Native FACU (NWPL)
Amaranthus australis SOUTHERN AMARANTH Native OBL (NWPL) T (WAP) OBL (DEP)
Amaranthus blitum subsp. emarginatus PURPLE AMARANTH Not Native
Amaranthus cannabinus TIDALMARSH AMARANTH Native OBL (NWPL) OBL (DEP)
Amaranthus caudatus LOVE-LIES-BLEEDING Not Native
Amaranthus crassipes SPREADING AMARANTH Not Native FAC (NWPL)
Amaranthus deflexus LARGEFRUIT AMARANTH Not Native
Amaranthus dubius SPLEEN AMARANTH Not Native
Amaranthus floridanus FLORIDA AMARANTH Native OBL (NWPL) OBL (DEP)
Amaranthus hybridus SLIM AMARANTH; PIGWEED Not Native
Amaranthus palmeri PALMER'S PIGWEED; CARELESSWEED Not Native FACU (NWPL)
Amaranthus polygonoides TROPICAL AMARANTH Not Native
Amaranthus retroflexus RED AMARANTH; ROUGH PIGWEED Not Native FAC (NWPL)
Amaranthus spinosus SPINY AMARANTH Not Native FACU (NWPL)
Amaranthus viridis SLENDER AMARANTH Not Native FAC (NWPL)
Identification Key
1.  Stem nodes usually with paired spines
1.  Stem nodes without spines
2
2.  Plant dioecious
3
2.  Plant monoecious, staminate and carpellate flowers intermingled or separated
6
3.  Leaf blades linear-oblong, <1.1 cm wide, those subtending the inflorescence <0.5 cm wide
3.  Leaf blades linear-oblong, lanceolate, to ovate, larger ones >1 cm wide, usually at least some subtending the inflorescence >0.5 cm wide
4
4.  Plant (0.25)0.5-1.5(3) m tall; petioles commonly subequal to longer than the leaf blade; staminate flower bracts longer than 2 mm, mostly with prominent midribs; outer staminate tepals with prominent midribs, usually longer than the inner tepals; carpellate flowers with 5 tepals, at least some >2 mm long; utricle circumscissile dehiscent
4.  Plant (0.25)1-3(9) m tall; petioles usually shorter than the leaf blade; staminate flower bracts 2 mm or shorter, midribs mostly not prominent or sometimes moderately prominent; outer staminate tepals without prominent midribs (sometimes moderately prominent), mostly not longer than the inner tepals; carpellate flower with 0-2 tepals, tepals usually <2 mm long; utricle indehiscent
5
5.  Staminate bracts 1.5-2 mm long, midribs prominent; utricles 1-2.5 mm long; seeds 1-1.2 mm wide
5.  Staminate bracts <1 mm long, midribs not prominent; utricles 2.5-4 mm long; seeds 2-3 mm wide
6.  Inflorescences predominantly of axillary clusters or glomerules, distal nodes sometimes condensed into leafy spikes
7
6.  Inflorescences predominantly terminal spikes and/or panicles, leafless or almost leafless at least in the distal part, axillary spikes or clusters usually also present
10
7.  Pistillate flowers usually with 3 tepals
8
7.  Pistillate flowers usually with (4-)5 tepals
9
8.  Leaf blades obtuse or acuminate to short-mucronate or shallowly emarginate at apex; utricles dehiscent
8.  Leaf blades usually deeply and broadly emarginate at apex; utricles indehiscent
9.  Inflorescence axes thickened, becoming indurate at maturity
9.  Inflorescence axes not thickened, not indurate at maturity
10.  Inflorescence bracts shorter than tepals; tepals of pistillate flowers usually 2-3; utricles indehiscent
11
10.  Inflorescence bracts usually exceeding tepals, sometimes shorter than tepals; tepals of pistillate flowers usually 5; utricles dehiscent
13
11.  Utricles distinctly rugose, equaling or slightly exceeding tepals
11.  Utricles smooth to faintly rugose, occasionally wrinkled or rugose in dry plants, distinctly exceeding tepals
12
12.  Plants annual; leaf blades usually deeply emarginate at apex; utricles subglobose to obovate, compressed; seeds filling fruit almost completely
12.  Plants short-lived perennial or annual; leaf blades retuse or shallowly emarginate at apex; utricles ellipsoid, slightly to distinctly inflated; seeds filling only proximal portions of fruit
13.  Tepals of pistillate flowers acute, acuminate, to aristate at apex
14
13.  Tepals of pistillate flowers obtuse, rounded, to emarginate at apex
15
14.  Bracts shorter than 2 mm, shorter than tepals; style branches strongly spreading; seeds 0.8-1 mm wide
14.  Bracts 2-7 mm, longer than or equaling tepals; style branches erect or slightly reflexed; seeds. 1-1.3 mm wide
15.  Inflorescences drooping, usually bright red to purple, occasionally white or yellowish, rarely green; bracts subequal to tepals and usually not exceeding style branches at maturity; seeds white, ivory, reddish, brown, or black
15.  Inflorescences erect or reflexed only at the tip, usually green, occasionally silvery green, sometimes reddish; bracts usually exceeding tepals and style branches; seeds brown to black
Genus Synonyms
Synonym Full Citation Basionym Type
Acanthochiton Acanthochiton Torrey, in Sitgreaves, Rep. Exp. Zuni & Colorado River 170. 1853. TYPE: Acanthochiton wrightii Torrey
Acnida Acnida Linnaeus, Sp. Pl. 1027. 1753. TYPE: Acnida cannabina Linnaeus
Albersia Albersia Kunth, Fl. Berol. 2: 144. 1838. TYPE: Albersia blitum (Linnaeus) Kunth (Amaranthus blitum Linnaeus) Substitute name for Blitum Scopoli 1772, non Linnaeus 1753.
Amblogyna Amblogyna Rafinesque, Fl. Tellur. 3: 42. 1837 ("1836"). TYPE: Amblogyna polygonoides (Linnaeus) Rafinesque (Amaranthus polygonoides Linnaeus) Substitute name for Roemeria Moench 1794, non Medikus 1792.
Bajan Bajan Adanson, Fam. Pl. 2: 506. 1763. TYPE: = Amaranthus Linnaeus 1753.
Bliton Bliton Adanson, Fam. Pl. 2: 506. 1763. TYPE: Non designatus.
Blitum Blitum Heister ex Fabricius, Enum. 198. 1759, non Linnaeus 1753, nec Hill 1757. TYPE: Non designatus.
Blitum Blitum Scopoli, Fl. Carn., ed. 2. 2: 236. 1772, non Linnaeus 1753, nec J. Hill 1757, nec Heister ex Fabricius 1759. TYPE: Blitum maius Scopoli (Amaranthus blitum Linnaeus) = Albersia Kunth 1838.
Dimeiandra Dimeiandra Rafinesque, Neogenyton 2. 1825. TYPE: Non designatus.
Dimeianthus Dimeianthus Rafinesque, Fl. Tellur. 3: 41. 1837 ("1836"). TYPE: = Bliton Adanson 1763.
Euxolus Euxolus Rafinesque, Fl. Tellur. 3: 42. 1837 ("1836"). TYPE: Euxolus deflexus (Linnaeus) Rafinesque (Amaranthus deflexus Linnaeus)
Galliaria Galliaria Bubani, Fl. Pyren. 1: 184. 1897. TYPE: = Albersia Kunth 1838.
Glomeraria Glomeraria Cavanilles, Descr. Pl. 319, 617. 1802. TYPE: Glomeraria viridis (Linnaeus) Cavanilles (Amaranthus viridis Linnaeus)
Mengea Mengea Schauer, in Meyen, Nov. Actorum Acad. Caes. Leop.-Carol. Nat. Cur. 19(Suppl. 1): 405. 1843. TYPE: Mengea peruviana Schauer
Montelia Montelia (Moquin-Tandon) A. Gray, Manual, ed. 2. 369. 1856. BASIONYM: Acnida Linnaeus, sect. Montelia Moquin-Tandon, in de Candolle, Prodr. 13(2): 277. 1849. TYPE: Montelia tamariscina (Nuttall) A. Gray (Amaranthus tamariscina Nuttall)
Pentrius Pentrius Rafinesque, Fl. Tellur. 3: 42. 1837 ("1836"). TYPE: Amaranthus oleraceus Linnaeus
Pyxidium Pyxidium Moench ex Montandon, Syn. Fl. Jura 260. 1856, non J. Hill 1771. TYPE: Non designatus.
Roemeria Roemeria Moench, Methodus 341. 1794, non Medikus 1792. TYPE: Roemeria polygonoides (Linnaeus) Moench (Amaranthus polygonoides Linnaeus) = Amblogyna Rafinesque 1837.
Sarratia Sarratia Moquin-Tandon, in de Candolle, Prodr. 13(2): 233, 268. 1849. TYPE: Non designatus.
Scleropus Scleropus Schrader, Index Sem. Hort. Goett. 1835: 5. 1835. TYPE: Scleropus amarantoides Schrader, Nom. illegit. (Amaranthus crassipes Schlechtendal)