SMOOTH PIGWEED, Amaranthus
hybridus L. 1, upper stem with leaves and flower clusters;
2, flower; 3, seed. Annual, reproducing by seeds.
Taproot shallow, reddish. Stems erect, up to 8 feet (2.4
m) tall, branching freely if not crowded. Leaves dull green, usually
at least 6 inches (15 cm) long when mature, ovate to lanceolate. Flowers
green, small, in slender, lax, paniclelike spikes with many short, crowded
lateral branches. Bracts and sepals slightly longer than utricles. Sepals
straight and acute. Seeds shiny black, lens-shaped, ovate, notched
at narrow end, about 1 mm in diameter. Found in cultivated fields,
yards, fence rows, and other waste places. Other species such as redroot
pigweed and Powell amaranth (Amaranthus powellii S.
Wats) are similar to smooth pigweed in morphology and weedy habits,
and may often be found in the same area. Powell amaranth has longer floral
bracts than smooth pigweed; has straight, acute sepals that are longer
than the utricle; has a stiff terminal inflorescence that either is simple
or has a few widely spaced, long lateral branches; and is found mainly
in northern part of region.