Plant: Annual herb, erect, 3-30 dm, monoecious Leaves: petiole 7-70 mm; blade 20-150 mm, lower diamond-shaped to widely ovate, upper ± lanceolate Inflorescence: generally panicle of spike-like clusters; axillary clusters generally many, 1-5 cm, ± 1-2.5 cm wide; terminal spike < or = 20 cm, 5 cm wide; bracts 2.5-4.5 mm, spined, midrib wide, green, margins scarious in lower 3/4 Flowers: Staminate flower: sepals 4-5, 2-3 mm, subequal; stamens (3)4-5; Pistillate flower: sepals 5, 2-3.2 mm, subequal, oblong to spoon-shaped, becoming reflexed, tip rounded to slightly notched, often abruptly pointed Fruit: ± 1.5 mm, circumscissile; lid smooth or wrinkled near base; Seed 1-1.3 mm, black Misc: Wet fields, roadside ditches, waste places; < 2400 m.