Polygonum nuttallii |
Polygonum bidwelliae |
|
---|---|---|
Nuttall's knotweed |
Bidwell knotweed, Bidwell's knotweed |
|
Habit | Herbs. | Herbs. |
Stems | spreading to erect, sometimes zigzagged, purplish, simple or branched, wiry, (5–)10–35 cm, papillose-scabridulous. |
erect, green, simple or divaricately branched, ± wiry, 2–20 cm, minutely papillose-scabridulous. |
Leaves | evenly distributed or crowded at branch tips, articulated to ocreae, basal leaves persistent, distal leaves gradually reduced to bracts; ocrea 3–4 mm, papillose-scabridulous, proximal part funnelform, distal part finely lacerate; petiole 0.1–2 mm; blade 1-veined, not pleated, linear to narrowly oblong-elliptic, 8–30 × 1–4(–7) mm, margins narrowly revolute, never touching along midrib, smooth, apex acute, mucronate, ± glaucous adaxially. |
crowded at branch tips, not articulated to ocreae, basal leaves caducous or persistent, distal leaves abruptly reduced to bracts; ocrea 8–13 mm, papillose-scabridulous, proximal part cylindric, distal part overlapping and obscuring leaves and flowers, silvery, entire or shallowly dentate; petiole absent; blade 3-veined, without pleats, linear, 5–15(–20) × 0.5–1.5(–2) mm, margins revolute, papillose-denticulate, apex spine-tipped. |
Inflorescences | axillary and terminal, spikelike, dense; cymes mostly congested toward tips of branches, 2–3-flowered. |
axillary; cymes in distal axils, 1-flowered. |
Pedicels | enclosed in ocreae, erect to spreading, 2–3 mm. |
absent. |
Flowers | semi-open or closed; perianth 1.8–2.4 mm; tube 25–33% of perianth length; tepals overlapping, greenish, white, or pink with pink margins, petaloid, oblong, cucullate, navicular in distal 1/4, apex rounded; midveins unbranched; stamens 8. |
closed; perianth 2–3 mm; tube 10–18% of perianth length; tepals overlapping, pink with pink or white margins, petaloid, elliptic, navicular, apex acute to acuminate; midveins unbranched; stamens 8. |
Achenes | enclosed in perianth, black, elliptic to ovate, 1.8–2.3 mm, faces subequal, shiny, smooth. |
enclosed in perianth at maturity, light brown to brown, ovate-elliptic, 1.8–2.3 mm, faces subequal, shiny, smooth. |
Polygonum nuttallii |
Polygonum bidwelliae |
|
Phenology | Flowering May–Oct. | Flowering May–Jun. |
Habitat | Dry prairies, open knolls in lower mountains, open sites in lowland and montane zones, sandy soil | Thin volcanic soils, chaparral, montane woodland valleys, grasslands |
Elevation | 800-1100 m (2600-3600 ft) | 60-1200 m (200-3900 ft) |
Distribution |
OR; WA; BC
|
CA
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Discussion | C. L. Hitchcock (1964) suggested that Polygonum nuttallii is but a small-flowered form of P. spergulariiforme. Although morphologically similar, P. nuttallii differs from P. spergulariiforme in some respects, including its wiry, purplish stems, short and funnelform ocreae, adaxially glaucous leaves, longer bracts, shorter fruiting perianth, and achenes. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Polygonum bidwelliae occurs in the Cascade Range and northeastern Sacramento Valley in Butte, Shasta, and Tehama counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 5, p. 570. | FNA vol. 5, p. 565. |
Parent taxa | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia | Polygonaceae > subfam. Polygonoideae > Polygonum > sect. Duravia |
Sibling taxa | ||
Synonyms | P. intermedium, P. douglasii subsp. nuttallii | |
Name authority | Small: Mongr. Amer. Sp. Polygonum, 132, plate 53. (1895) | S. Watson: Proc. Amer. Acad. Arts 14: 294. (1879) |
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