8. Polygonum Prolificum (Small) Robinson. Proliferous Knotweed

Fig. 1622

P.ramosissimum prolificum Small, Bull. Torr. Club 21:

171. 1894. P. prolificum Robinson, Rhodora 4: 68. 1902.

Annual, glabrous, stem erect or nearly so, 1 1/2° tall or less, usually much branched. Leaves narrow, spatulate, linear-spatulate or nearly oblong, rather slender-petioled, 5"-15" long, obtuse or acutish; ocreae inconspicuous, early much-lacerate; flowers exceeded by the ocreae; calyx sessile or nearly so, the sepals pinkish, slightly enlarged in fruit; stamens mostly 5; achene rhombic-ovoid, about 1 1/4" long, 3-angled, slightly roughened, abruptly contracted at the apex.

In brackish marshes and on the sea-shore, Quebec and Maine to Virginia; and in the interior from South Dakota to Missouri and Colorado. July-Oct.

9. Polygonum Atlanticum (Robinson) Bick-Nell. Atlantic Coast Knotweed

Fig. 1623

Polygonum ramosissimum atlanticum Robinson, Rhodora 4:

72. 1902. P. atlanticum Bicknell, Bull. Torr. Club 36: 450. 1909.

Annual, glabrous, bright-green, stem erect, 1°-3° tall, terete, but striate. Leaves narrowly elliptic or linear-elliptic, or broadest above or below the middle, slender-petioled, 10"-25" long, acute or slightly acuminate at both ends; ocreae brown, early much-lacerate; calyx long-pedicelled, the sepals 5 or rarely 6, with pink margins; stamens mostly 5; achene ovoid or rhombic-ovoid, about 1 1/2" long, 3-angled, smooth and shining.

In salt marshes and low brackish grounds, Maine to Rhode Island. Aug.-Sept.

Polygonum Bellardi All., admitted into our first edition, appears in our range only as a waif from the Old World.

9 Polygonum Atlanticum Robinson Bick Nell Atlantic 16239 Polygonum Atlanticum Robinson Bick Nell Atlantic 1624

10. Polygonum Erectum L. Erect Knotweed

Fig. 1624

Polygonum erectum L. Sp. Pl. 363. 1753.

Annual, glabrous, yellowish-green, stem erect or ascending, 8'-2° high, terete, nearly simple or much branched. Leaves oval, oblong or obovate, subses-sile or short-petioled, 3"-18" long, obtuse or subacute at the apex, conspicuously jointed to the ocreae; ocreae oblique, soon lacerate, silvery when young; flowers 1-2 together in the axils; sepals greenish-yellow or yellowish, enlarged in fruit; stamens 6 (sometimes 5); achene ovoid-pyramidal, 3-angled, 1"-1 1/2" long, dull, invested by the calyx, or the apex slightly protruding.

In moist or dry soil, Ontario to the Northwest Territory, Tennessee and Arkansas. July-Sept.

11. Polygonum Ramosissimum Michx. Mushy Knotweed

Fig. 1625

P. ramosissimum Michx. Fl. Bor. Am. 1: 237. 1803.

Annual, yellowish or yellowish-green, glabrous, stem erect or ascending, usually very much branched, slender, striate, usually rigid, 4'-4° tall. Leaves lanceolate or linear-oblong, short-petioled, 3"-2o" long, acute or acuminate at both ends; ocreae few-nerved, becoming deeply lacerate; flowers several together in the axillary clusters, short-pedicelled; sepals 5 or 6, yellow or yellowish, 1"-1 1/2" long; stamens 6 or fewer; achene 3-angled, acute, sometimes slightly protruding beyond the calyx, nearly 1 1/2"-2" long, black.

In saline soil, Minnesota to the Northwest Territory, New Mexico and California. July-Sept.

Polygonum camporum Meisn., admitted into our first edition, is here omitted as not certainly known within our area.

11 Polygonum Ramosissimum Michx Mushy Knotweed 162511 Polygonum Ramosissimum Michx Mushy Knotweed 1626