Black Fringed Knotweed

Á. Löve and D. Löve (1982) reported a chromosome count of 2n = 20 for Fallopia cilinodis. All other counts summarized by J. P. Bailey and C. A. Stace (1992) and counts by M. H. Kim et al. (2000) are 2n = 22. It is not known if the 2n = 20 count is an error.

Herbs, perennial, not rhizomatous, 1-5 m. Stems usually scandent or sprawling, rarely erect, freely branched, herbaceous, pilose-hispid or, rarely, subglabrous, not glaucous. Leaves: ocrea usually deciduous, light brown, cylindric, 3-4 mm, margins oblique, base fringed with reflexed hairs and slender bristles, face glabrous or puberulent; petiole 1-6 cm, retrorsely pubescent; blade cordate-ovate, cordate-hastate, or cordate-sagittate, 2-6(-12) × 2-5(-10) cm, base cordate, margins wavy, often reddish-ciliate, apex acute to acuminate, abaxial face pilose-hispid, not minutely dotted, not glaucous, adaxial face glabrous. Inflorescences terminal and axillary, erect or spreading, paniclelike, 4-10(-15) cm, axes reddish-pilose; peduncle 1-12 cm, retrorsely pubescent. Pedicels ascending or spreading, articulated near middle or distally, 3-4 mm, glabrous or puberulent. Flowers bisexual, 4-7 per ocreate fascicle; perianth nonaccrescent, greenish white to white, 1.5-2 mm including stipelike base, glabrous; tepals elliptic, apex obtuse to acute, outer 3 obscurely keeled; stamens 6-8; filaments flattened proximally, pubescent proximally; styles connate basally; stigmas capitate. Achenes included or exserted, brownish black to black, 3-4 × 1.8-2.4 mm, shiny, smooth; fruiting perianth glabrous, wings absent. 2n = 22.

Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Sask.; Conn., Ga., Ill., Ind., Ky., Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., Tenn., Vt., Va., W.Va., Wis.

Flowering Jun-Oct.

Dry woods, thickets, clearings; 0-900m.

Polygonum cilinode Michaux, Fl. Bor.-Amer. 1: 241. 1803; Bilderdykia cilinodis (Michaux) Greene; B. cilinodis var. laevigata (Fernald) C. F. Reed; Polygonum cilinode var. laevigatum Fernald; Reynoutria cilinodis (Michaux) Shinners; Tiniaria cilinodis (Michaux) Small