Amaranthus cruentus L., Amaranthaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Amaranthus paniculatus L.

Common name(s): [more details]

Chinese: lao ya gu

English: African-spinach, Indian-spinach, Sudan-spinach, blood amaranth, bush greens, caterpillar amaranth, panicled amaranth, purple amaranth, red amaranth, red shank, wild amaranth

French: amarante, amarante étalée, queue de renard

Spanish: achita, bledo

Habit:  herb

Description:  "To 6 ft.; leaves long-petioled, to 12 in. long, ovate-lanceolate to rhombic; inflorescence a terminal panicle of red or purple spikes, lateral spikes mostly horizontally divergent.  Probably a cultigen, and by some treated as a variety of A. hybridus."  (Bailey & Bailey, 1976; p. 65)

A. hybridus:  "Annual herb, erect or less commonly ascending, up to 2 (-3) m in cultivated forms, but much less in spontaneous plants, not infrequently reddish tinted throughout.  Stems stout, branched, angular, glabrous or thinly to moderately furnished with short or long multicellular hairs (increasingly so above, especially in the inflorescence).  Leaves glabrous, or thinly pilose on the lower margins and underside of the primary nervation, long-petiolate (petioles up to 15 cm but even then scarcely exceeding the lamina); lamina broadly lanceolate to rhomboid or ovate, 3-19 (-30) x 1.5-8 (-12) cm, gradually narrowed to the blunt to subacute mucronulate tip, attenuate or shortly cuneate into the petiole below.  Flowers in yellowish, green, reddish or purple axillary and terminal spikes formed of cymose clusters, which are increasingly closely approximate upwards, the terminal inflorescence varying from a single spike to a broad much-branched panicle up to more or less 45 x 25 cm, the ultimate spike not infrequently nodding; male and female flowers intermixed throughout the spikes.  Bracts and bracteoles deltoid-ovate to deltoid-lanceolate, pale and membranous, acuminate and with a long pale to reddish-tipped erect arista formed by the stout excurrent yellow or greenish midrib; bracteoles subequalling to much exceeding the perianth.  Perianth-segments 5, lanceolate or oblong, 1.5-3.5 mm, acute-aristate or the inner in female sometimes blunt, only the midrib at most greenish.  Stigmas (2-) 3, erect, flexuose or recurved, more or less 0.75-1.25 mm.  Capsule subglobose to ovoid to ovoid-urceolate, 2-3 mm, circumscissile, with a moderately distinct to obsolete beak, lid smooth, longitudinally sulcate or sometimes rugulose below the neck.  Seed black and shining, or pale, compressed, 0.75-1.25 mm, almost smooth centrally, faintly reticulate around the margins.

subsp. hybridus:  "Stigma-bases and upper part of lid of fruit swollen so that the fruit has a distinct inflated beak.  Inner perianth-segments of female flowers commonly acute.  Longer bracteoles of female flowers mostly about twice as long as the perianth.

subsp. cruentus [=A. cruentus]:  "Longer bracteoles of female flowers mostly 1-1.5 times as long as the perianth.  Stigma-bases and upper part of lid of fruit scarcely swollen, fruit with a short, smooth beak.  Inner perianth-segments of female flowers commonly obtuse"  (Townsend, 1985; pp. 25-26).

Habitat/ecology:  In East Africa, "commonly as a weed of cultivation, also on broken waste ground, in short grassland and in shaded places at forest edges; 20-1790 m" [A. hybridus subsp. cruentus] (Townsend, 1985; pp. 25-26).  In Hawai‘i, A. cruentus is an escape from cultivation (Wagner et al., 1999; pp. 186, 189). In New Zealand, "crops, gardens, waste places in settled areas" (Webb et al., 1988; p. 104). In Papua New Guinea, "probably associated exclusively with areas under cultivation at 1200-2200 m altitude"  (Womersley, 1978; p. 23).

Propagation:  Seed

Native range:  "Presumably of Central American origin, now widespread in tropical and subtropical regions of the world; the red form (which is probably of cultivated derivation) is cultivated as an ornamental in temperate regions also, occasionally escaping there." (Townsend, 1985; pp. 25-26)

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	Hawaiian Islands	introduced cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 186) Occasional escape.
New Caledonia Îles Loyauté (Loyalte Islands)	Îles Loyauté (Loyalty Islands)	introduced invasive	Tassin, Jacques (2005)
New Caledonia New Caledonia	New Caledonia Islands		Swarbrick, John T. (1997) (p. 88)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	Tassin, Jacques (2005)
New Caledonia New Caledonia Archipelago	Île des Pins (Isle of Pines)	introduced invasive	Tassin, Jacques (2005)
Papua New Guinea Bismarck Archipelago	Bismarck Archipelago	cultivated	Peekel, P. G. [translated by E. E. Henty] (1984) (p. 164) Leaf-vegetable, in the gardens and plantations of the natives.
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	introduced invasive	Womersley, John S., ed. (1978) (pp. 23-24)
Philippines Philippine Islands	Philippine Islands	introduced invasive cultivated	Merrill, Elmer D. (1923) (p. 128) As Amaranthus paniculatus L. In oopen waste places at low and medium altitudes, sometimes cultivated; certainly introduced.
Solomon Islands Solomon Islands	Solomon Islands		Swarbrick, John T. (1997) (p. 88)
Tonga Vava‘u Group	Vava‘u Island		Yuncker, T. G. (1959) (p. 107) As Amaranthus paniculatus L. Cited: Barlay.
Vanuatu New Hebrides Islands	Vanuatu (Republic of)		Swarbrick, John T. (1997) (p. 88)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Australia (continental)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 18)
China China	China (People's Republic of)	introduced cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 182)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 104)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Indian Ocean offshore islands) Christmas Island Group	Christmas Island	extirpated	Swarbrick, J. T. (1997) (p. 103)
Australia (Indian Ocean offshore islands) Christmas Island Group	Christmas Island	native	Orchard, Anthony E., ed. (1993) (p. 16)

Control:  If you know of control methods for Amaranthus cruentus, please let us know.