Polygonum spergulariiforme

Meisner ex Small
Bull. Torrey Bot. Club 19: 366. 1892.
Common names: Spurry or fall knotweed
Synonyms: Polygonum douglasii subsp. spergulariiforme (Meisner ex Small) J. C. Hickman Polygonum emaciatum A. Nelson
Treatment appears in FNA Volume 5. Treatment on page 570. Mentioned on page 562, 568.

Herbs. Stems erect, green, divaricately branched, not wiry, 5–50 cm, usually papillose-scabrid-ulous, rarely glabrescent. Leaves uniformly distributed, articulated to ocreae, basal leaves usually caducous, distal leaves abruptly reduced to bracts, articulated to ocreae; ocrea 8–12 mm, papillose-scabridulous, proximal part cylindric, distal part disintegrating into a few persistent fibers; petiole 0.1–2 mm; blade 1-veined, not pleated, linear to lanceolate, 35–60 × 1–3 mm, margins flat or narrowly revolute, smooth or papillose-denticulate, apex acute, mucronate. Inflorescences axillary and terminal, spikelike, dense; cymes crowded, ± overlapping at branch tips, 2–5-flowered. Pedicels enclosed in or slightly exserted from ocreae, erect to spreading, 0.5–2 mm. Flowers open or semi-open; perianth 3–5 mm; tube 9–17% of perianth length; tepals overlapping, uniformly pink or white, petaloid, oblong-obovate, cucullate, navicular in distal 1/4, apex rounded; midveins branched; stamens 8. Achenes enclosed in perianth, black, narrowly elliptic or elliptic-lanceolate to narrowly ovate, 3–5 mm, faces subequal, shiny, smooth to striate-tubercled.

Phenology: Flowering Jun–Oct.
Habitat: Moist to dry, open rocky places, including serpentine
Elevation: 10-2000 m


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B.C., Calif., Idaho, Mont., Oreg., Wash., Wyo.


Selected References


Lower Taxa


Mihai Costea +, François J. Tardif +  and Harold R. Hinds† +
Meisner ex Small +
Spurry or fall knotweed +
B.C. +, Calif. +, Idaho +, Mont. +, Oreg. +, Wash. +  and Wyo. +
10-2000 m +
Moist to dry, open rocky places, including serpentine +
Flowering Jun–Oct. +
Bull. Torrey Bot. Club +
Polygonum douglasii subsp. spergulariiforme +  and Polygonum emaciatum +
Polygonum spergulariiforme +
Polygonum sect. Duravia +
species +