Northern jointweed

Polygonum articulatum Linnaeus, Sp. Pl. 1: 363. 1753

Herbs, annual, synoecious, 1-5 dm. Stems erect, branched proximally and distally, glabrous. Leaves persistent or fugaceous; ocrea margins not ciliate; blade linear to narrowly clavate, (1.5-)5-20(-35) × 0.4-1.2 mm, base barely tapered, margins not hyaline, apex obtuse, glabrous. Inflorescences (13-)20-33(-40) mm; ocreola encircling rachis, only the base adnate to rachis, apex acute. Pedicels spreading in anthesis, reflexed in fruit, 0.9-2.1 mm, longer than subtending ocreola. Flowers bisexual; outer tepals loosely appressed in anthesis and fruit, pink to white, occasionally red, distal portion of midrib often inconspicuously greenish, elliptic to obovate, 1.3-2.3 mm in flower, margins entire to erose; inner tepals loosely appressed in anthesis and fruit, white to pink, occasionally red, elliptic, 1.3-2.3 mm in anthesis, margins mostly entire; filaments dimorphic; anthers yellow or pink; styles and stigmas ca. 0.1 mm in anthesis. Achenes included or exserted, reddish brown, 3(-4)-gonous, 2-2.8 × 1-1.3 mm, shiny, smooth. 2n = 32.

Flowering Sep-Nov. Pine barrens, sandhills, and sandy sites along lake shores, beaches, river banks, roadsides, and railroads; 0-500 m; Ont., P.E.I., Que.; Conn., Del., Ga., Ill., Ind., Iowa, Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Pa., R.I., Wis., Vt., Va.