34.
Amaranthus tricolor
Linnaeus, Sp. Pl. 2: 989. 1753.
Joseph's coat, summer poinsettia
Plants
annual, glabrous.
Stems
erect, often branched, 0.8-1.5 m.
Leaves:
petiole
1
/2 as long as blade; blade ovate, elliptic, rhombic, or lanceolate, mostly 4-12 × 1.4-6 cm, base tapering, margins entire, usually undulate, apex acuminate and short-mucronate; distal leaf blades green, red, scarlet, maroon, purple, yellow, and cream (unique to
A. tricolor
).
Inflorescences
axillary glomerules.
Bracts
of pistillate flowers ovate to lanceolate, 5-6 mm.
Pistillate flowers:
tepals 3, narrowly ovate to lanceolate, 5-6 mm, apex aristate; style branches spreading; stigmas 2-3.
Staminate flowers
intermixed with pistillate; tepals 3; stamens 3.
Utricles
ovoid, 2-2.5 mm, rugose, dehiscence regularly circumscissile.
Seeds
black or brownish black, subglobose, 1 mm diam., shiny.
Flowering summer-fall. Locally escaped from cultivation, disturbed areas; introduced; La., Mich., Mo.; native in tropical Asia.
Amaranthus tricolor
is widely cultivated as a garden plant for its showy, often variegated, distal leaves of striking colors---red, scarlet, maroon, purple, yellow, cream, and green. Other cultivated varieties with green leaves are sometimes cultivated as a potherb. Escaped plants sometimes occur near places of cultivation; we have no evidence of widespread establishment.
