SWAMP SMARTWEED, Polygonum
coccineum Muhl. 1, upper part of plant; 2, portion
of rhizome; 3, seed. Perennial, reproducing by long, creeping,
tough, woody, horizontal rhizomes and by seed. Stems erect, 1 to
3 feet (0.3 to 0.9 m) long, enlarged at nodes, usually unbranched; may
produce roots at nodes. Leaves alternate, oblong, 2-1/2 to 8 inches
(6.3 to 20 cm) long, pointed at tip, rounded at base with prominent veins.
A sheath at base of each leaf surrounds stem. Flowers rose in color
and produced in compact erect spike I to 3 inches (2.5 to 7.5 cm) long.
Seeds oval, flattened on one side, black, shiny, and slightly rough;
however, not usually produced in northern areas. Found usually in
low, wet places in fields, gardens, or roadsides, but may be present elsewhere.
The extensive root system makes it a strong competitor with other plants
and difficult to kill. Also commonly known as tanweed and devil's shoestring.