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FNA | Family List | FNA Vol. 5 | Polygonaceae | Polygonum

31. Polygonum majus (Meisner) Piper, Fl. Palouse Reg. 63. 1901.

Wiry knotweed

Polygonum coarctatum Douglas ex Meisner var. majus Meisner in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 101. 1856; P. douglasii Greene subsp. majus (Meisner) J. C. Hickman

Herbs. Stems erect, green, simple or branched, ± wiry, 15-60 cm, usually papillose-scabridulous. Leaves uniformly distributed, articulated to ocreae, basal leaves often caducous, distal leaves abruptly reduced to bracts, articulated to ocreae; ocrea 5-12 mm, glabrous or papillose-scabridulous, proximal part cylindric, distal part lacerate or disintegrating into fibers; petiole 0.1-2 mm; blade 1-veined, not pleated, linear to narrowly oblong or lanceolate, 15-70 × 2-8 mm, margins revolute, papillose-denticulate, apex acute or mucronate. Inflorescences axillary and terminal, spikelike, elongate; cymes spaced along branches, 2-5-flowered. Pedicels exserted from ocreae, reflexed, 0.5-1 mm. Flowers open or semi-open; perianth (3.5-)4-5 mm; tube 9-17% of perianth length; tepals overlapping, uniformly white to pink, petaloid, oblong to oblong-obovate, cucullate, navicular in distal 1/ 4, apex rounded; midveins unbranched or with short lateral branches; stamens 8. Achenes enclosed in perianth, black, elliptic, 3.5-5 mm, faces subequal, shiny or dull, smooth or striate-tubercled.

Flowering May-Aug. Dry plains, meadows, sometimes on serpentine; 500-2000 m; B.C.; Calif., Colo., Idaho, Nev., Oreg., Utah, Wash., Wyo.


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