Tall Jointweed

Herbs, annual, dioecious, 8-16 dm. Stems erect, simple or branched proximally and distally, glabrous. Leaves mostly fuga­-ceous; ocrea margins not ciliate; blade filiform to broadly spatulate or, rarely, obovate, (9-)19-39(-65) × 0.8-5(-8) mm, base attenuate, margins not hyaline, apex obtuse, glabrous. Inflorescences (13-)20-40(-70) mm; ocreola encircling rachis, only the base adnate to rachis, apex acute. Pedicels spreading in anthesis, sharply reflexed in fruit, 0.1-0.3 mm, as long as subtending ocreola. Flowers functionally unisexual; filaments dimorphic; anthers deep red; styles and stigmas less than 0.1 mm in anthesis. Staminate flowers: outer tepals loosely appressed in anthesis and fruit, white, elliptic, 1.1-2 mm in anthesis, margins entire; inner tepals loosely appressed in anthesis and fruit, white, elliptic, 1-2 mm in anthesis, margins entire. Pistillate flowers: outer tepals loosely appressed in anthesis, usually spreading in fruit, white to pink, often drying red and streaked or dotted orange or brown, elliptic to oblong, 0.8-1.4 mm in anthesis, margins entire or obscurely erose; inner tepals loosely appressed in anthesis and fruit, white to pink, often drying yellow, broadly elliptic to ovate, 1.8-3.6 mm in flower, margins entire or obscurely erose. Achenes included or exserted, reddish brown to yellow-brown, (2-)3-gonous, 2-3.4 × 1-1.4 mm, shiny, smooth. 2n = 22, 24.

Ala., Fla., Ga., Miss., N.C., S.C.

Flowering Aug-Nov.

Pinelands, sandhills, sandy roadsides; 0-60m.

Polygonum gracile Nuttall, Gen. N. Amer. Pl. 1: 255. 1818, not Salisbury 1796