1. Polygonum Maritimum L. Seaside Knot-Weed

Fig. 1615

Polygonum maritimum L. Sp. PI. 361. 1753. Polygonum glaucum Nutt. Gen. 1: 254. 1818.

Perennial, glaucous, often nearly white, glabrous, root usually deep, woody, stem prostrate or ascending, branched, 8'-2o' long, deeply striate. Leaves oblong, elliptic or sometimes ovate, mostly equalling or longer than the internodes, 3"-12" long, fleshy, veined beneath, somewhat rugose above, the margins often revolute; ocreae large, silvery, at length lacerate, becoming brown at the base; flowers 1-3 together in the axils, becoming slender-pedicelled; sepals white or pinkish, the margins decidedly pink; achene 3-angled, ovoid, 1 1/2-2" long, acute or blunt, smooth, shining, longer than the calyx.

In sands of the seashore, Massachusetts to Florida. Also on the coast of Europe. Coast knot-grass. July-Sept.

2. Polygonum Fowleri Robinson. Fowler's Knotweed

Fig. 1616

Polygonum Fowleri Robinson, Rhodora 4: 67. 1902.

Perennial, glabrous, pale green or slightly glaucous, stem 3'-24' long, prostrate, usually much branched, striate. Leaves ovate-lanceolate, oblong or obovate, 3"-15" long, short-petioled, obtuse or abruptly pointed at the apex, veined beneath, inconspicuoulsy so above, shorter than the internodes or equalling them; ocreae becoming lacerate, silvery, brown and glaucous at the base when old; flowers 2-4 together in the axils; sepals greenish, or the margins white or pinkish: achene ovoid, 3-angled, 2"-2i" long, slightly granular but shining, acuminate, exceeding the calyx.

In waste places, New Brunswick, Anticosti and Quebec to Maine. Also from Alaska to Washington. May-Sept. P. Rayi Babington, with which this was confused in our first edition, is not definitely known to occur on this continent.

3. Polygonum Leptocarpum Robinson. Narrow-Pointed Knotweed

Fig. 1617

Polygonum leptocarpum Robinson, Proc. Bost. Soc. Nat. Hist. 31: 263. 1904.

Annual, glabrous, stem very slender, copiously branched, about 1° tall, nearly terete, the branches angled. Leaves various, the lower ones early deciduous the upper ones linear-lanceolate to linear, 3"-4" long, acute, pale green; ocreae becoming very finely lacerate, brown or reddish-brown at the base; flowers sessile or nearly so; sepals 4 or 5, green and with whitish or reddish margins; stamens 4 or 5, included; style 3-parted; achene slender, 3-angled, lanceolate, less than 1 1/2" long, curved at the apex.

Kansas. Sept.-Oct.

4. Polygonum Exsertum Small. Long-Fruited Knotweed

Fig. 1618

P. exsertum Small, Bull. Torr. Club 21: 172. 1894.

Annual, glabrous, sometimes slightly glaucous, stem slender, brownish, erect or nearly so, conspicuously striate, branched, 1 1/2°-3° tall. Leaves lanceolate, rarely oblanceolate, 1/2'-1 1/2" long, acute or cuspidate at the apex, acuminate at the base, nearly sessile; ocreae soon lacerate, silvery, becoming brownish; sepals 6, greenish, with white margins; stamens 5 or 6, included; achene stout, 3-angled, 2 1/2"-3" long, more or less constricted above the middle, chestnut-brown, smooth, shining, 2-3 times as long as the calyx, at length twisted.

In brackish marshes, New Brunswick to New Jersey; and on prairies and sand bars, Saskatchewan to Illinois and Nebraska. Aug.-Oct. This is considered by some a "semi viviparous " state of P. ramosissimum.