POL YGONA CEA E. 365 



29. Polygonum tenue Michx. Slender Knotweed. (I. F. f. 1346.) Annual, 

 glabrous, somewhat rough about the nodes; stem very slender or filiiorm, erect, 

 somewhat 4-angled, 1-4 dm. tall. Leaves linear or linear-lanceolate, sessile, 

 acuminate at the apex, o 5-2.5 cm. long, articulated to the ocreae, i-ribbed with a 

 lateral impression on each side of the rib, the margins minutely scabrous or serru- 

 late ; ocreae funnelform, soon lacerate ; flowers several in the axillary clusters, 

 green, subsessile ; calyx-lobes whitish ; stamens 8 ; style 3 -parted nearly to the 

 base, its branches diverging ; fruit erect ; achene 3 angled, black, 2-2.5 mm - long, 

 reticulated on the angles, the centre of its faces smooth. Dry soil, Me. and Ont. 

 to Minn., Neb., Ga. and Ark. July-Sept. 



30. Polygonum Douglasii Greene. Douglas' Knotweed. (I. F. f. 1347.) 

 Annual, similar to the preceding species, glabrous, somewhat rough at the nodes, 

 sometimes slightly glaucous ; stem erect, 2-5 dm. tall, simple or usually much 

 branched. Leaves oblong or narrowly lanceolate, 1-5 cm. long, subsessile, rather 

 thin, flat or revolute, with no lateral impressions parallel to the midrib ; ocreae 

 oblique, short, soon lacerate ; clusters axillary, several -flowered ; the flowers and 

 fruit deflexed ; calyx green with white or rose-colored margin ; stamens 8 ; style 

 3-parted ; achene 3-angled, 2.5-4 mm. long, oblong or ovoid-oblong, black, smooth 

 and shining. N. \V. Terr, and Br. Col. to N. Mex., Neb. and Ind. Terr., east 

 through Ont. to northern N. Y. and Vt. June-Sept. 



31. Polygonum Convolvulus L. Black Bindweed. (I. F. f. 1348.) Annual, 

 glabrous, scurfy; stem twining or trailing, 1. 5-10 dm. long, mostly branched. 

 Leaves ovate-sagittate or the uppermost lanceolate-sagittate, long-petioled, acumi- 

 nate at the apex, slightly ciliate, 1-7.5 cm - l° n g; ocreae oblique, short, rough on 

 the margin ; axillary clusters or racemes loosely flowered; flowers greenish, pen- 

 dulous on slender pedicels ; calyx 5-parted or rarely 6-parted, closely investing the 

 achene, the outer lobes slightly or rot at all keeled ; stamens 8 ; style nearly 

 entire ; stigmas 3 ; achene 3-angled, obovoid-pyramidal, 3 mm. long, thick- 

 pointed, black, granular, rather dull. In waste and cultivated grounds, nearly 

 throughout N. Am., except the extreme north. Naturalized from Europe. Native 

 of Asia. Sometimes a troublesome weed. July-Sept. 



32. Polygonum cilinode Michx. Fringed Black Bindweed. (I. F. f. 1349.) 

 Perennial, sparingly pubescent; stem red or reddish, twining or prostrate, 0.3-3 m - 

 long. Leaves broadly ovate or somewhat hastate, acuminate at the apex, cordate 

 at the base, rather long-petioled, undulate, finely ciliate, 2.5-10 cm. long, or the 

 upper smaller ; ocreae small, armed with reflexed bristles near the base ; racemes 

 mostly panicled, axillary and terminal, interrupted ; calyx whitish ; style short, 

 3 parted to the base ; achene 3 angled, oblong-pyramidal or ovoid, nearly 3 mm. 

 long, very smooth and shining. In rocky places, N. S. to Ont., Minn, and Penn., 

 south in the Alleghanies to N. Car. June-Sept. 



Polygonum cilinode brevis Peck. Stems erect, about 3 dm. tall; inflorescence mostly 

 terminal. Adirondack Mountains, N. Y. 



33. Polygonum scandens L. Climbing False Buckwheat. (I. F. f. 135 1.) 

 Perennial, glabrous; stem climbing, 0.5-6 m. long, rather stout, branched, rough 

 on the ridges. Leaves ovate, acuminate, cordate at the base, 2.5-15 cm. long or 

 the upper smaller, the larger long-petioled, finely punctate, the margins scabrous; 

 ocreae oblique, smooth and glabrous; racemes usually numerous and panicled, 

 interrupted, leafy, 5-20 cm. long; flowers yellowish-green, long-pediceled; calyx 

 5-parted, the three outer segments very strongly winged and decurrent on the 

 pedicels, especially in fruit; style almost none; stigmas 3; fruiting calyx IO-I2 

 mm. long, the wings crisped, not incised; achene 4-5 mm. long, 3-angled, rather 

 blunt at both ends, smooth, shining. In woods and thickets, N. S. to Ont. and the 

 Rocky Mts., south to Fla., Neb. and Tex. Aug. -Sept. 



34. Polygonum dumetorum L. Copse or Hedge Buckwheat. (I. F. f. 

 1350.) Perennial, glabrous, similar to the preceding species; stem extensively 

 twining, 0.5-3 m - l° n g- much branched. Leaves ovate or somewhat hastate, and 

 sometimes inequilateral, acuminate at the apex, cordate at the base, 2.5-7 cm. 

 long, long-petioled, or the upper smaller or nearly sessile; ocreae oblique, smooth; 

 racemes numerous, much interrupted, leafy bracted, 5-13 cm. long; flowers yellow- 

 ish green, pendulous; calyx 5-parted, the three outer segments winged or keeled 



